{"collection":"scripture-revelation","full_text_available":true,"graph_url":"https://unchartedknowledge.5gfusion.net/v2/api/page/gutenberg_15620/graph","html_url":"https://unchartedknowledge.5gfusion.net/v2/page/gutenberg_15620","id":"gutenberg_15620","license":"Public Domain (US)","rights_basis":"gutenberg_metadata_copyright_false","source":"gutenberg","source_url":"https://www.gutenberg.org/ebooks/15620","summary":null,"tags":["Astronomy","Category: Religion/Spirituality","Category: Science - Physics"],"text":"Produced by Robert J. Hall.\n\n\n\n\n[Page ii]\n[Illustration: THE CONSTELLATIONS OF ORION AND TAURUS.\n\nNOTES.--Star a in Taurus is red, has eight metals; moves east (page\n227). At o above tip of right horn is the Crab Nebula (page 219).\nIn Orion, a is variable, has five metals; recedes 22 miles per\nsecond. b, d, e, x, r, etc., are double stars, the component parts\nof various colors and magnitudes (page 212, note). l and i are\ntriple; s, octuple; th, multiple, surrounded by a fine Nebula (page\n218).]\n\n\n\n\n[Page iii]\nRECREATIONS IN ASTRONOMY\n\nWITH\n\n_DIRECTIONS FOR PRACTICAL EXPERIMENTS AND TELESCOPIC WORK_\n\n\nBY\n\nHENRY WHITE WARREN, D.D.\n\nAUTHOR OF \"SIGHTS AND INSIGHTS; OR, KNOWLEDGE BY TRAVEL,\" ETC.\n\n\nWITH EIGHTY-THREE ILLUSTRATIONS AND MAPS OF STARS\n\n\n\n[Page v]\n[Greek:\n  TAEI PSUCHAEI\n  TAEI AGAPAETAEI\n  ASTRAPOUSAEI\n  KAI\n  ISAGGEDOI]\n\n\n\n\n[Page vii]\nPREFACE.\n\nAll sciences are making an advance, but Astronomy is moving at the\ndouble-quick. Since the principles of this science were settled\nby Copernicus, four hundred years ago, it has never had to beat\na retreat. It is rewritten not to correct material errors, but\nto incorporate new discoveries.\n\nOnce Astronomy treated mostly of tides, seasons, and telescopic\naspects of the planets; now these are only primary matters. Once\nit considered stars as mere fixed points of light; now it studies\nthem as suns, determines their age, size, color, movements, chemical\nconstitution, and the revolution of their planets. Once it considered\nspace as empty; now it knows that every cubic inch of it quivers with\ngreater intensity of force than that which is visible in Niagara.\nEvery inch of surface that can be conceived of between suns is more\nwave-tossed than the ocean in a storm.\n\nThe invention of the telescope constituted one era in Astronomy;\nits perfection in our day, another; and the discoveries of the\nspectroscope a third--no less important than either of the others.\n\nWhile nearly all men are prevented from practical experimentation\nin these high realms of knowledge, few [Page viii] have so little\nleisure as to be debarred from intelligently enjoying the results\nof the investigations of others.\n\nThis book has been written not only to reveal some of the highest\nachievements of the human mind, but also to let the heavens declare\nthe glory of the Divine Mind. In the author's judgment, there is no\ngulf that separates science and religion, nor any conflict where\nthey stand together. And it is fervently hoped that anyone who\ncomes to a better knowledge of God's works through reading this\nbook, may thereby come to a more intimate knowledge of the Worker.\n\nI take great pleasure in acknowledging my indebtedness to J. M.\nVan Vleck, LL.D., of the U.S. Nautical Almanac staff, and Professor\nof Astronomy at the Wesleyan University, for inspecting some of the\nmore important chapters; to Dr. S. S. White, of Philadelphia, for\ntelescopic advantages; to Professor Henry Draper, for furnishing,\nin advance of publication, a photograph of the sun's corona in 1878;\nand to the excellent work on \"Popular Astronomy,\" by Professor\nSimon Newcomb, LL.D., Professor U. S. Naval Observatory, for some\nof the most recent information, and for the use of the unequalled\nengravings of Jupiter, Saturn, and the great nebula of Orion.\n\n\n\n\n[Page ix]\nCONTENTS.\n\n  CHAP.\n    I. CREATIVE PROCESSES\n   II. CREATIVE PROGRESS\n        Constitution of Light\n        Chemistry of Suns revealed by Light\n        Creative Force of Light\n  III. ASTRONOMICAL INSTRUMENTS\n        The Telescope\n        The Reflecting Telescope\n        The Spectroscope\n   IV. CELESTIAL MEASUREMENTS\n        Celestial Movements\n        How to Measure\n    V. THE SUN\n        What the Sun does for us\n   VI. THE PLANETS, AS SEEN FROM SPACE\n        The Outlook from the Earth\n  VII. SHOOTING-STARS, METEORS, AND COMETS\n        Aerolites\n        Comets\n        Famous Comets\n        Of what do Comets consist?\n        Will Comets strike the Earth?\n VIII. THE PLANETS AS INDIVIDUALS\n        Vulcan\n        Mercury\n        Venus\n        The Earth\n        The Aurora Borealis\n[Page x]\n        The Delicate Balance of Forces\n        Tides\n        The Moon\n        Telescopic Appearance\n        Eclipses\n        Mars\n        Satellites of Mars\n        Asteroids\n        Jupiter\n        Satellites of Jupiter\n        Saturn\n        Rings of Saturn\n        Satellites of Saturn\n        Uranus\n        Neptune\n   IX. THE NEBULAR HYPOTHESIS.\n    X. THE STELLAR SYSTEM\n        The Open Page of the Heavens\n        Equatorial Constellations\n        Characteristics of the Stars\n        Number\n        Double and Multiple Stars\n        Colored Stars\n        Clusters of Stars\n        Nebul\u00e6\n        Variable Stars\n        Temporary, New, and Lost Stars\n        Movements of Stars\n   XI. THE WORLDS AND THE WORD\n  XII. THE ULTIMATE FORCE\n SUMMARY OF LATEST DISCOVERIES AND CONCLUSIONS\n SOME ELEMENTS OF THE SOLAR SYSTEM\n EXPLANATION OF ASTRONOMICAL SYMBOLS\n        Signs of the Zodiac\n        Other Abbreviations Used in the Almanac\n        Greek Alphabet Used Indicating the Stars\n CHAUTAUQUA OUTLINE FOR STUDENTS\n GLOSSARY OF ASTRONOMICAL TERMS AND INDEX\n\n\n\n\n[Page xi]\nILLUSTRATIONS\n\nFIG.\n     The Constellations of Orion and Taurus\n  1. An Orbit resulting from Attraction and Projection\n  2. The Moon's Orbit about the Earth\n  3. Changes of Orbit by Mutual Attraction\n  4. Velocity of Light measured by Jupiter's Satellites\n  5. Velocity of Light measured by Fizeau's Toothed Wheel\n  6. White Light resolved into Colors\n  7. Showing amount of Light received by Different Planets\n  8. Measuring Intensities of Lights\n  9. Reflection and Diffusion of Light\n 10. Manifold Reflections\n 11. Refraction by Water\n 12. Atmospherical Reflection\n 13. Refracting Telescope\n 14. Reflecting Telescope\n 15. The Cambridge Equatorial Refractor\n 16. The new Reflecting Telescope at Paris\n 17. Spectroscope, with Battery of Prisms\n 18. Spectra of Glowing Hydrogen and of the Sun\n 19. Illustrating Arcs and Angles\n 20. Measuring Objects by observing Angles\n 21. Mural Circle\n 22. Scale to measure Hundredths of an Inch\n 23. Spider-lines to determine Star Transits\n 24. Illustrating Triangulation\n[Page xii]\n 25. Measuring Distance to an Inaccessible Object\n 26. Measuring Elevation of an Inaccessible Object\n 27. Illustrating Parallax\n 28. Illustrating Stellar Parallax\n 29. Mode of Ascertaining Longitude\n 30. Relative Size of Sun, as seen from Different Planets\n 31. Zodiacal Light\n 32. Corona of the Sun in 1858--Brazil\n 33. Corona of the Sun in 1878--Colorado\n 34. Solar Prominences of Flaming Hydrogen\n 35. Changes in Solar Cavities during Rotation\n 36. Solar Spot\n 37. Holding Telescope to see the Sun-spots\n 38. Orbits and Comparative Sizes of the Planets\n 39. Orbit of Earth, illustrating Seasons\n 40. Inclination of Planes of Planetary Orbits\n 41. Inclination of Orbits of Earth and Venus\n 42. Showing the Sun's Movement among the Stars\n 43. Passage of the Sun by Star Regulus\n 44. Apparent Path of Jupiter among the Stars\n 45. Illustrating Position of Planets\n 46. Apparent Movements of an Inferior Planet\n 47. Apparent Movements of a Superior Planet\n 47_a_. A Swarm of Meteors meeting the Earth\n 48. Explosion of a Bolide\n 49. Flight of Bolides\n 50. The Santa Rosa Aerolite\n 51. Orbit of November Meteors and the Comet of 1866\n 52. Aspects of Remarkable Comets\n 53. Phases and Apparent Dimensions of Venus\n 54. The Earth and Moon in Space\n 55. Aurora as Waving Curtains\n 56. Tide resulting from Centrifugal Motion\n 57. Lunar Landscape\n[Page xiii]\n 58. Telescopic View of the Moon\n 59. Illumination of Lunar Craters and Peaks\n 60. Lunar Crater \"Copernicus\"\n 61. Eclipses: Shadows of Earth and Moon\n 62. Apparent Sizes of Mars, seen from the Earth\n 63. Jupiter\n 64. Various Positions of Jupiter's Satellites\n 65. View of Saturn and his Rings\n 66. Perturbations of Uranus\n 67. Map: Circumpolar Constellations\n 68. Map of Constellations on the Meridian in December\n 69. Map of Constellations on the Meridian in January\n 70. Map of Constellations on the Meridian in April\n 71. Map of Constellations on the Meridian in June\n 72. Map of Constellations on the Meridian in September\n 73. Map of Constellations on the Meridian in November\n 74. Southern Circumpolar Constellations\n 75. Aspects of Double Stars\n 76. Sprayed Star Cluster below ae in Hercules\n 77. Globular Star Cluster in the Centaur\n 78. Great Nebula about th Orionis\n 79. The Crab Nebula above z Tauri\n 80. The Ring Nebula in Lyra\n 81. Showing Place of Ring Nebula\n 82. The Horizontal Pendulum\n\n  COLORED PLATE REPRESENTING VARIOUS SPECTA\n  MAPS TO FIND THE STARS\n\n\n\n\n[Page 1]\nI.\n\nCREATIVE PROCESSES.\n\n    \"In the beginning God created the heaven and the earth. And the\n  earth was without form, and void; and darkness was upon the face of the\n  deep.\"--_Genesis_ i. 1, 2.\n\n[Page 2]\n \"Not to the domes, where crumbling arch and column\n    Attest the feebleness of mortal hand,\n  But to that fane, most catholic and solemn,\n    Which God hath planned,--\n  To that cathedral, boundless as our wonder,\n    Whose quenchless lamps the sun and stars supply;\n  Its choir the winds and waves, its organ thunder,\n    Its dome the sky.\"    H. W. LONGFELLOW.\n\n \"The heavens are a point from the pen of His perfection;\n  The world is a rose-bud from the bower of His beauty;\n  The sun is a spark from the light of His wisdom;\n  And the sky a bubble on the sea of His power.\"\n    SIR W. JONES.\n\n\n[Page 3]\nRECREATIONS IN ASTRONOMY.\n\n       *       *       *       *       *\n\nI.\n\n_CREATIVE PROCESSES._\n\nDuring all the ages there has been one bright and glittering page\nof loftiest wisdom unrolled before the eye of man. That this page\nmay be read in every part, man's whole world turns him before it.\nThis motion apparently changes the eternally stable stars into a\nmoving panorama, but it is only so in appearance. The sky is a\nvast, immovable dial-plate of \"that clock whose pendulum ticks\nages instead of seconds,\" and whose time is eternity. The moon\nmoves among the illuminated figures, traversing the dial quickly,\nlike a second-hand, once a month. The sun, like a minute-hand, goes\nover the dial once a year. Various planets stand for hour-hands,\nmoving over the dial in various periods reaching up to one hundred\nand sixty-four years; while the earth, like a ship of exploration,\nsails the infinite azure, bearing the observers to different points\nwhere they may investigate the infinite problems of this mighty\nmachinery.\n\nThis dial not only shows present movements, but it keeps the history\nof uncounted ages past ready to be [Page 4] read backward in proper\norder; and it has glorious volumes of prophecy, revealing the\nfar-off future to any man who is able to look thereon, break the\nseals, and read the record. Glowing stars are the alphabet of this\nlofty page. They combine to form words. Meteors, rainbows, auroras,\nshifting groups of stars, make pictures vast and significant as the\narmies, angels, and falling stars in the Revelation of St.\nJohn--changing and progressive pictures of infinite wisdom and\npower.\n\nMen have not yet advanced as far as those who saw the pictures John\ndescribes, and hence the panorama is not understood. That continuous\nspeech that day after day uttereth is not heard; the knowledge that\nnight after night showeth is not seen; and the invisible things\nof God from the creation of the world, even his eternal power and\nGodhead, clearly discoverable from things that are made, are not\napprehended.\n\nThe greatest triumphs of men's minds have been in astronomy--and\never must be. We have not learned its alphabet yet. We read only\neasy lessons, with as many mistakes as happy guesses. But in time we\nshall know all the letters, become familiar with the combinations,\nbe apt at their interpretation, and will read with facility the\nlessons of wisdom and power that are written on the earth, blazoned\nin the skies, and pictured by the flowers below and the rainbows\nabove.\n\nIn order to know how worlds move and develop, we must create them;\nwe must go back to their beginning, give their endowment of forces,\nand study the laws of their unfolding. This we can easily do by that\nfaculty wherein man is likest his Father, a creative imagination.\nGod creates and embodies; we create, but [Page 5] it remains in\nthought only. But the creation is as bright, strong, clear,\nenduring, and real, as if it were embodied. Every one of us would\nmake worlds enough to crush us, if we could embody as well as\ncreate. Our ambition would outrun our wisdom. Let us come into the\nhigh and ecstatic frame of mind which Shakspeare calls frenzy, in\nthe exigencies of his verse, when\n\n \"The poet's eye, in a fine frenzy rolling,\n  Doth glance from heaven to earth, from earth to heaven;\n  And, as imagination bodies forth\n  The forms of things unknown, the poet's pen\n  Turns them to shapes, and gives to airy nothing\n  A local habitation and a name.\"\n\nIn the supremacy of our creative imagination let us make empty\nspace, in order that we may therein build up a new universe. Let us\nwave the wand of our power, so that all created things disappear.\nThere is no world under our feet, no radiant clouds, no blazing\nsun, no silver moon, nor twinkling stars. We look up, there is\nno light; down, through immeasurable abysses, there is no form;\nall about, and there is no sound or sign of being--nothing save\nutter silence, utter darkness. It cannot be endured. Creation is\na necessity of mind--even of the Divine mind.\n\nWe will now, by imagination, create a monster world, every atom\nof which shall be dowered with the single power of attraction.\nEvery particle shall reach out its friendly hand, and there shall\nbe a drawing together of every particle in existence. The laws\ngoverning this attraction shall be two. When these particles are\nassociated together, the attraction shall be in proportion to the\nmass. A given mass will pull twice [Page 6] as much as one of half\nthe size, because there is twice as much to pull. And a given mass\nwill be pulled twice as much as one half as large, because there is\ntwice as much to be pulled. A man who weighed one hundred and fifty\npounds on the earth might weigh a ton and a half on a body as large\nas the sun. That shall be one law of attraction; and the other shall\nbe that masses attract inversely as the square of distances between\nthem. Absence shall affect friendships that have a material basis.\nIf a body like the earth pulls a man one hundred and fifty pounds at\nthe surface, or four thousand miles from the centre, it will pull\nthe same man one-fourth as much at twice the distance, one-sixteenth\nas much at four times the distance. That is, he will weigh by a\nspring balance thirty-seven and a half pounds at eight thousand\nmiles from the centre, and nine pounds six ounces at sixteen\nthousand miles from the centre, and he will weigh or be pulled by\nthe earth 1/24 of a pound at the distance of the moon. But the moon\nwould be large enough and near enough to pull twenty-four pounds on\nthe same man, so the earth could not draw him away. Thus the two\nlaws of attraction of gravitation are--1, _Gravity is proportioned\nto the quantity of matter_; and 2, _The force of gravity varies\ninversely as the square of the distance from the centre of the\nattracting body_.\n\nThe original form of matter is gas. Almost as I write comes the\nannouncement that Mr. Lockyer has proved that all the so-called\nprimary elements of matter are only so many different sized molecules\nof one original substance--hydrogen. Whether that is true or not,\nlet us now create all the hydrogen we can [Page 7] imagine, either\nin differently sized masses or in combination with other substances.\nThere it is! We cannot measure its bulk; we cannot fly around it in\nany recordable eons of time. It has boundaries, to be sure, for we\nare finite, but we cannot measure them. Let it alone, now; leave it\nto itself. What follows? It is dowered simply with attraction. The\nvast mass begins to shrink, the outer portions are drawn inward.\nThey rush and swirl in vast cyclones, thousands of miles in extent.\nThe centre grows compact, heat is evolved by impact, as will be\nexplained in Chapter II. Dull red light begins to look like coming\ndawn. Centuries go by; contraction goes on; light blazes in\ninsufferable brightness; tornadoes, whirlpools, and tempests\nscarcely signify anything as applied to such tumultuous tossing.\n\nThere hangs the only world in existence; it hangs in empty space.\nIt has no tendency to rise; none to fall; none to move at all in\nany direction. It seethes and, flames, and holds itself together\nby attractive power, and that is all the force with which we have\nendowed it.\n\nLeave it there alone, and withdraw millions of miles into space:\nit looks smaller and smaller. We lose sight of those distinctive\nspires of flame, those terrible movements. It only gives an even\neffulgence, a steady unflickering light. Turn one quarter round.\nStill we see our world, but it is at one side.\n\nNow in front, in the utter darkness, suddenly create another world\nof the same size, and at the same distance from you. There they\nstand--two huge, lone bodies, in empty space. But we created them\ndowered with attraction. Each instantly feels the drawing influence\nof the other. They are mutually attractive, and begin to [Page 8]\nmove toward each other. They hasten along an undeviating straight\nline. Their speed quickens at every mile. The attraction increases\nevery moment. They fly swift as thought. They dash their flaming,\nseething foreheads together.\n\nAnd now we have one world again. It is twice as large as before,\nthat is all the difference. There is no variety, neither any motion;\njust simple flame, and nothing to be warmed thereby. Are our creative\npowers exhausted by this effort?\n\n[Illustration: Fig. 1.--Orbit A D, resulting from attraction, A\nC, and projectile force, A B.]\n\nNo, we will create another world, and add another power to it that\nshall keep them apart. That power shall be what is called the force\nof inertia, which is literally no power at all; it is an inability\nto originate or change motion. If a body is at rest, inertia is\nthat quality by which it will forever remain so, unless acted upon\nby some force from without; and if a body is in motion, it will\ncontinue on at the same speed, in a straight line, forever, unless\nit is quickened, retarded, or turned from its path by some other\nforce. Suppose our newly created sun is 860,000 miles in diameter.\nGo away 92,500,000 miles and create an earth eight thousand miles\nin diameter. It instantly feels the attractive power of the sun\ndrawing it to itself sixty-eight [Page 9] miles a second. Now, just\nas it starts, give this earth a push in a line at right angles with\nline of fall to the sun, that shall send it one hundred and\neighty-nine miles a second. It obeys both forces. The result is that\nthe world moves constantly forward at the same speed by its inertia\nfrom that first push, and attraction momentarily draws it from its\nstraight line, so that the new world circles round the other to the\nstarting-point. Continuing under the operation of both forces, the\nworlds can never come together or fly apart.\n\nThey circle about each other as long as these forces endure; for\nthe first world does not stand still and the second do all the\ngoing; both revolve around the centre of gravity common to both.\nIn case the worlds are equal in mass, they will both take the same\norbit around a central stationary point, midway between the two.\nIn case their mass be as one to eighty-one, as in the case of the\nearth and the moon, the centre of gravity around which both turn\nwill be 1/81 of the distance from the earth's centre to the moon's\ncentre. This brings the central point around which both worlds\nswing just inside the surface of the earth. It is like an apple\nattached by a string, and swung around the hand; the hand moves\na little, the apple very much.\n\nThus the problem of two revolving bodies is readily comprehended.\nThe two bodies lie in easy beds, and swing obedient to constant\nforces. When another body, however, is introduced, with its varying\nattraction, first on one and then on the other, complications are\nintroduced that only the most masterly minds can follow. Introduce\na dozen or a million bodies, and complications arise that only\nOmniscience can unravel.\n\n[Page 10]\n[Illustration: Fig. 2.]\n\nLet the hand swing an apple by an elastic cord. When the apple\nfalls toward the earth it feels another force besides that derived\nfrom the hand, which greatly lengthens the elastic cord. To tear\nit away from the earth's attraction, and make it rise, requires\nadditional force, and hence the string is lengthened; but when\nit passes over the hand the earth attracts it downward, and the\nstring is very much shortened: so the moon, held by an elastic cord,\nswings around the earth. From its extreme distance from the earth,\nat A, Fig. 2, it rushes with increasing speed nearly a quarter of a\nmillion of miles toward the sun, feeling its attraction increase\nwith every mile until it reaches B; then it is retarded in its\nspeed, by the same attraction, as it climbs back its quarter of\na million of miles away from the sun, in defiance of its power,\nto C. All the while the invisible elastic force of the earth is\nunweariedly maintained; and though the moon's distances vary over a\nrange of 31,355 miles, the moon is always in a determinable place.\nA simple revolution of one world about another in a circular orbit\nwould be a problem of easy solution. It would always be at the\nsame distance from its centre, and going with the same velocity.\nBut there are over sixty causes that interfere with such a simple\norbit in the case of the moon, all of which causes and their\ndisturbances must be considered in calculating such a simple matter\nas an eclipse, or predicting the moon's place as the sailors guide.\nOne of the most puzzling of the irregularities [Page 11] of our\nnight-wandering orb has just been explained by Professor Hansen, of\nGotha, as a curious result of the attraction of Venus.\n\n[Illustration: Fig. 3.--Changes of orbit by mutual attraction.]\n\nTake a single instance of the perturbations of Jupiter and Saturn\nwhich can be rendered evident. The times of orbital revolution of\nSaturn and Jupiter are nearly as five to two. Suppose the orbits of\nthe planets to be, as in Fig. 3, both ellipses, but not necessarily\nequally distant in all parts. The planets are as near as possible\nat 1, 1. Drawn toward each other by mutual attraction, Jupiter's\norbit bends outward, and Saturn's becomes more nearly straight, as\nshown by the dotted lines. A partial correction of this difficulty\nimmediately follows. As Jupiter moves on ahead of Saturn it is held\nback--retarded in its orbit by that body; and Saturn is hastened\nin its orbit by the attraction of Jupiter. Now greater speed means\na straighter orbit. A rifle-ball flies nearer in a straight line\nthan a thrown stone. A greater velocity given to a whirled ball\npulls the elastic cord far enough to give the ball a larger orbit.\nHence, being hastened, Saturn stretches out nearer its proper orbit,\nand, retarded, Jupiter approaches the smaller curve that is its\ntrue orbit.\n\nBut if they were always to meet at this point, as they would if\nJupiter made two revolutions to Saturn's one, it would be disastrous.\nIn reality, when Saturn has gone around two-thirds of its orbit to\n2, Jupiter will have gone once and two-thirds around and overtaken\n[Page 12] Saturn; and they will be near again, be drawn together,\nhastened, and retarded, as before; their next conjunction would be\nat 3, 3, etc.\n\nNow, if they always made their conjunction at points equally distant,\nor at thirds of their orbits, it would cause a series of increasing\ndeviations; for Jupiter would be constantly swelling his orbit at\nthree points, and Saturn increasingly contracting his orbit at\nthe same points. Disaster would be easily foretold. But as their\ntimes of orbital revolutions are not exactly in the ratio of five\nand two, their points of conjunction slowly travel around the orbit,\ntill, in a period of nine hundred years, the starting-point is\nagain reached, and the perturbations have mutually corrected one\nanother.\n\nFor example, the total attractive effect of one planet on the other\nfor 450 years is to quicken its speed. The effect for the next 450\nyears is to retard. The place of Saturn, when all the retardations\nhave accumulated for 450 years, is one degree behind what it is\ncomputed if they are not considered; and 450 years later it will\nbe one degree before its computed place--a perturbation of two\ndegrees. When a bullet is a little heavier or ragged on one side,\nit will constantly swerve in that direction. The spiral groove in\nthe rifle, of one turn in forty-five feet, turns the disturbing\nweight or raggedness from side to side--makes one error correct\nanother, and so the ball flies straight to the bull's-eye. So the\nplace of Jupiter and Saturn, though further complicated by four\nmoons in the case of Jupiter, and eight in the case of Saturn, and\nalso by perturbations caused by other planets, can be calculated\nwith exceeding nicety.\n\nThe difficulties would be greatly increased if the orbits [Page 13]\nof Saturn and Jupiter, instead of being 400,000,000 miles apart,\nwere interlaced. Yet there are the orbits of one hundred and\nninety-two asteroids so interlaced that, if they were made of wire,\nno one could be lifted without raising the whole net-work of them.\nNevertheless, all these swift chariots of the sky race along the\ncourse of their intermingling tracks as securely as if they were\neach guided by an intelligent mind. _They are guided by an\nintelligent mind and an almighty arm._\n\nStill more complicated is the question of the mutual attractions of\nall the planets. Lagrange has been able to show, by a mathematical\ngenius that seems little short of omniscience in his single department\nof knowledge, that there is a discovered system of oscillations,\naffecting the entire planetary system, the periods of which are\nimmensely long. The number of these oscillations is equal to that\nof all the planets, and their periods range from 50,000 to 2,000,000\nyears,\n\nLooking into the open page of the starry heavens we see double\nstars, the constituent parts of which must revolve around a centre\ncommon to them both, or rush to a common ruin. Eagerly we look\nto see if they revolve, and beholding them in the very act, we\nconclude, not groundlessly, that the same great law of gravitation\nholds good in distant stellar spaces, and that there the same sufficient\nmind plans, and the same sufficient power directs and controls all\nmovements in harmony and security.\n\nWhen we come to the perturbations caused by the mutual attractions\nof the sun, nine planets, twenty moons, one hundred and ninety-two\nasteroids, millions [Page 14] of comets, and innumerable meteoric\nbodies swarming in space, and when we add to all these, that belong\nto one solar system, the attractions of all the systems of the other\nsuns that sparkle on a brilliant winter night, we are compelled to\nsay, \"As high as the heavens are above the earth, so high above our\nthoughts and ways must be the thoughts and ways of Him who\ncomprehends and directs them all.\"\n\n\n\n\n[Page 15]\nII.\n\nCREATIVE PROGRESS.\n\n  \"And God said, Let there be light, and there was light.\"--_Genesis_\n  i., 3.\n\n  \"God is light.\"--1 _John_, i. 5.\n\n[Page 16]\n  \"Hail! holy light, offspring of Heaven first born,\n  Or of the eternal, co-eternal beam,\n  May I express thee unblamed? since God is light,\n  And never but in unapproached light\n  Dwelt from eternity, dwelt then in thee,\n  Bright effluence of bright essence increate.\"\n    MILTON.\n\n  \"A million torches lighted by Thy hand\n  Wander unwearied through the blue abyss:\n  They own Thy power, accomplish Thy command,\n  All gay with life, all eloquent with bliss.\n  What shall we call them? Piles of crystal light--\n  A glorious company of golden streams--\n  Lamps of celestial ether burning bright--\n  Suns lighting systems with their joyous beams?\n  But 'Thou to these art as the noon to night.\"\n    DERZHAVIN, trans. by BOWRING.\n\n\n\n\n[Page 17]\nII.\n\n_CREATIVE PROGRESS._\n\nWorlds would be very imperfect and useless when simply endowed\nwith attraction and inertia, if no time were allowed for these\nforces to work out their legitimate results. We want something\nmore than swirling seas of attracted gases, something more than\ncompacted rocks. We look for soil, verdure, a paradise of beauty,\nanimal life, and immortal minds. Let us go on with the process.\n\nLight is the child of force, and the child, like its father, is full\nof power. We dowered our created world with but a single quality--a\nforce of attraction. It not only had attraction for its own material\nsubstance, but sent out an all-pervasive attraction into space. By\nthe force of condensation it flamed like a sun, and not only lighted\nits own substance, but it filled all space with the luminous outgoings\nof its power. A world may be limited, but its influence cannot;\nits body may have bounds, but its soul is infinite. Everywhere is\nits manifestation as real, power as effective, presence as actual,\nas at the central point. He that studies ponderable bodies alone\nis not studying the universe, only its skeleton. Skeletons are\nsomewhat interesting in themselves, but far more so when covered\nwith flesh, flushed with beauty, and inspired with soul. The\nuniverse [Page 18] has bones, flesh, beauty, soul, and all is one.\nIt can be understood only by a study of all its parts, and by\ntracing effect to cause.\n\nBut how can condensation cause light? Power cannot be quiet. The\nmighty locomotive trembles with its own energy. A smitten piece\nof iron has all its infinitesimal atoms set in vehement commotion;\nthey surge back and forth among themselves, like the waves of a\nstorm-blown lake. Heat is a mode of motion. A heated body commences\na vigorous vibration among its particles, and communicates these\nvibrations to the surrounding air and ether. When these vibrations\nreach 396,000,000,000,000 per second, the human eye, fitted to be\naffected by that number, discerns the emitted undulations, and the\nobject seems to glow with a dull red light; becoming hotter, the\nvibrations increase in rapidity. When they reach 765,000,000,000,000\nper second the color becomes violet, and the eye can observe them no\nfarther. Between these numbers are those of different rapidities,\nwhich affect the eye--as orange, yellow, green, blue, indigo, in an\nalmost infinite number of shades--according to the sensitiveness\nof the eye.\n\nWe now see how our dark immensity of attractive atoms can become\nluminous. A force of compression results in vibrations within,\ncommunicated to the ether, discerned by the eye. Illustrations are\nnumerous. If we suddenly push a piston into a cylinder of brass,\nthe force produces heat enough to set fire to an inflammable substance\nwithin. Strike a half-inch cube of iron a moderate blow and it becomes\nwarm; a sufficient blow, and its vibrations become quick enough to\nbe seen--it is red-hot. Attach a thermometer to an extended [Page\n19] arm of a whirling wheel; drive it against the air five hundred\nfeet per second, the mercury rises 16\u00b0. The earth goes 98,000 feet\nper second, or one thousand miles a minute. If it come to an\naerolite or mass of metallic rock, or even a cloudlet of gas,\nstanding still in space, its contact with our air evolves 600,000\u00b0\nof heat. And when the meteor comes toward the world twenty-six miles\na second, the heat would become proportionally greater if the meteor\ncould abide it, and not be consumed in fervent heat. It vanishes\nalmost as soon as seen. If there were meteoric masses enough lying\nin our path, our sky would blaze with myriads of flashes of light.\nEnough have been seen to enable a person to read by them at night.\nIf a sufficient number were present, we should miss their individual\nflashes as they blend their separate fires in one sea of\ninsufferable glory. The sun is 1,300,000 times as large as our\nplanet; its attraction proportionally greater; the aerolites more\nnumerous; and hence an infinite hail of stones, small masses and\nlittle worlds, makes ceaseless trails of light, whose individuality\nis lost in one dazzling sea of glory.\n\nOn the 1st day of September, 1859, two astronomers, independently\nof each other, saw a sudden brightening on the surface of the sun.\nProbably two large meteoric masses were travelling side by side\nat two or three hundred miles per second, and striking the sun's\natmosphere, suddenly blazed into light bright enough to be seen\non the intolerable light of the photosphere as a background. The\nearth responded to this new cause of brilliance and heat in the\nsun. Vivid auroras appeared, not only at the north and south poles,\nbut even where such spectacles are seldom seen. The electro-magnetic\n[Page 20] disturbances were more distinctly marked. \"In many places\nthe telegraphic wires struck work. In Washington and Philadelphia\nthe electric signalmen received severe electric shocks; at a station\nin Norway the telegraphic apparatus was set fire to; and at Boston a\nflame of fire followed the pen of Bain's electric telegraph.\" There\nis the best of reason for believing that a continuous succession of\nsuch bodies might have gone far toward rendering the earth\nuncomfortable as a place of residence.\n\nOf course, the same result of heat and light would follow from\ncompression, if a body had the power of contraction in itself. We\nendowed every particle of our gas, myriads of miles in extent, with an\nattraction for every other particle. It immediately compressed itself\ninto a light-giving body, which flamed out through the interstellar\nspaces, flushing all the celestial regions with exuberant light.\n\nBut heat exerts a repellent force among particles, and soon an\nequilibrium is reached, for there comes a time when the contracting\nbody can contract no farther. But heat and light radiate away into\ncold space, then contraction goes on evolving more light, and so\nthe suns flame on through the millions of years unquenched. It is\nestimated that the contraction of our sun, from filling immensity\nof space to its present size, could not afford heat enough to last\nmore than 18,000,000 years, and that its contraction from its present\ndensity (that of a swamp) to such rock as that of which our earth\nis composed, could supply heat enough for 17,000,000 years longer.\nBut the far-seeing mind of man knows a time must come when the\npresent force of attraction [Page 21] shall have produced all the\nheat it can, and a new force of attraction must be added, or the sun\nitself will become cold as a cinder, dead as a burned-out char.\n\nSince light and heat are the product of such enormous cosmic forces,\nthey must partake of their nature, and be force. So they are. The\nsun has long arms, and they are full of unconquerable strength\nninety-two millions, or any other number of millions, of miles\naway. All this light and heat comes through space that is 200\u00b0\nbelow zero, through utter darkness, and appears only on the earth.\nSo the gas is darkness in the underground pipes, but light at the\nburner. So the electric power is unfelt by the cable in the bosom\nof the deep, but is expressive of thought and feeling at the end.\nHaving found the cause of light, we will commence a study of its\nqualities and powers.\n\nLight is the astronomer's necessity. When the sublime word was\nuttered, \"Let there be light!\" the study of astronomy was made\npossible. Man can gather but little of it with his eye; so he takes\na lens twenty-six inches in diameter, and bends all the light that\npasses through it to a focus, then magnifies the image and takes\nit into his eye. Or he takes a mirror, six feet in diameter, so\nhollowed in the middle as to reflect all the rays falling upon it\nto one point, and makes this larger eye fill his own with light.\nBy this larger light-gathering he discerns things for which the\nlight falling on his pupil one-fifth of an inch in diameter would\nnot be sufficient. We never have seen any sun or stars; we have\nonly seen the light that left them fifty minutes or years ago, more\nor less. Light is the a\u00ebrial sprite that carries our measuring-rods\nacross the infinite [Page 22] spaces; light spreads out the history\nof that far-off beginning; brings us the measure of stars a thousand\ntimes brighter than our sun; takes up into itself evidences of the\nvery constitutional elements of the far-off suns, and spreads them\nat our feet. It is of such capacity that the Divine nature, looking\nfor an expression of its own omnipotence, omniscience, and power of\nrevelation, was content to say, \"God is Light.\" We shall need all\nour delicacy of analysis and measurement when we seek to determine\nthe activities of matter so fine and near to spirit as light.\n\n[Illustration: Fig. 4.--Velocity of Light measured by Eclipses of\nJupiter's Moons.]\n\nWe first seek the velocity of light. In Fig. 4 the earth is 92,500,000\nmiles from the sun at E; Jupiter is 480,000,000 miles from the sun\nat J. It has four moons: the inner one goes around the central\nbody in forty-two hours, and is eclipsed at every revolution. The\nlight that went out from the sun to M ceases to be reflected back\nto the earth by the intervention of the planet Jupiter. We know\nto a second when these eclipses take place, and they can be seen\nwith a small telescope. But when the earth is on the opposite side\nof the sun [Page 23] from Jupiter, at E', these eclipses at J' take\nplace sixteen and a half minutes too late. What is the reason? Is\nthe celestial chronometry getting deranged? No, indeed; these great\nworlds swing never an inch out of place, nor a second out of time.\nBy going to the other side of the sun the earth is 184,000,000 miles\nfarther from Jupiter, and the light that brings the intelligence of\nthat eclipse consumes the extra time in going over the extra\ndistance. Divide one by the other and we get the velocity, 185,000\nmiles per second. That is probably correct to within a thousand\nmiles. Methods of measurement by the toothed wheel of Fizeau confirm\nthis result. Suppose the wheel, Fig. 5, to have one thousand teeth,\nmaking five revolutions to the second. Five thousand flashes of\nlight each second will dart out. Let each flash travel nine miles to\na mirror and return. If it goes that distance in 1/10000 of a\nsecond, or at the rate of 180,000 miles a second, the next tooth\nwill have arrived before the eye, and each returning ray be cut off.\nHasten the revolutions a little, and the next notch will then admit\nthe ray, on its return, that went out of each previous notch: the\neighteen miles having been traversed meanwhile. The method of\nmeasuring by means of a revolving mirror, used by Faucault, is held\nto be even more accurate.\n\n[Illustration: Fig. 5.--Measuring the Velocity of Light.]\n\nWhen we take instantaneous photographs by the exposure [Page 24] of\nthe sensitive plate 1/20000 part of a second, a stream of light nine\nmiles long dashes in upon the plate in that very brief period of\ntime.\n\nThe highest velocity we can give a rifle-ball is 2000 feet a second,\nthe next second it is only 1500 feet, and soon it comes to rest.\nWe cannot compact force enough behind a bit of lead to keep it\nflying. But light flies unweariedly and without diminution of speed.\nWhen it has come from the sun in eight minutes, Alpha Centauri\nin three years, Polaris in forty-five years, other stars in one\nthousand, its wings are in nowise fatigued, nor is the rapidity\nof its flight slackened in the least.\n\nIt is not the transactions of to-day that we read in the heavens,\nbut it is history, some of it older than the time of Adam. Those\nstars may have been smitten out of existence decades of centuries\nago, but their poured-out light is yet flooding the heavens.\n\nIt goes both ways at once in the same place, without interference.\nWe see the light reflected from the new moon to the earth; reflected\nback from the house-tops, fields, and waters of earth, to the moon\nagain, and from the moon to us once more--three times in opposite\ndirections, in the same place, without interference, and thus we\nsee \"the old moon in the arms of the new.\"\n\n_Constitution of Light._\n\n[Illustration: Fig. 6.--White Light resolved into Colors.]\n\nLight was once supposed to be corpuscular, or consisting of transmitted\nparticles. It is now known to be the result of undulations in ether.\nReference has been made to the minuteness of these undulations.\nTheir velocity is equally wonderful. Put a prism of glass into\na ray of light coming into a dark room, and it is [Page 25]\ninstantly turned out of its course, some parts more and some less,\naccording to the number of vibrations, and appears as the seven\ncolors on different parts of the screen. Fig. 6 shows the\narrangement of colors, and the number of millions of millions of\nvibrations per second of each. But the different divisions we call\ncolors are not colors in themselves at all, but simply a different\nnumber of vibrations. Color is all in the eye. Violet has in\ndifferent places from 716 to 765,000,000,000,000 of vibrations per\nsecond; red has, in different places, from 396 to\n470,000,000,000,000 vibrations per second. None of these in any\nsense are color, but affect the eye differently, and we call these\ndifferent effects color. They are simply various velocities of\nvibration. An object, like one kind of stripe in our flag, which\nabsorbs all kinds of vibrations except those between 396 and\n470,000,000,000,000, and reflects those, appears red to us. The\nfield for the stars absorbs and destroys all but those vibrations\nnumbering about 653,000,000,000,000 of [Page 25] vibrations per\nsecond. A color is a constant creation. Light makes momentary color\nin the flag. Drake might have written, in the continuous present as\nwell as in the past,\n\n \"Freedom mingles with its gorgeous dyes\n  The milky baldrick of the skies,\n  And stripes its pore celestial white\n  With streakings of the morning light.\"\n\nEvery little pansy, tender as fancy, pearled with evanescent dew,\nfresh as a new creation of sunbeams, has power to suppress in one\npart of its petals all vibrations we call red, in another those\nwe call yellow, and purple, and reflect each of these in other\nparts of the same tender petal. \"Pansies are for thoughts,\" even\nmore thoughts than poor Ophelia knew. An evening cloud that is\ndense enough to absorb all the faster and weaker vibrations, leaving\nonly the stronger to come through, will be said to be red; because\nthe vibrations that produce the impression we have so named are\nthe only ones that have vigor enough to get through. It is like an\narmy charging upon a fortress. Under the deadly fire and fearful\nobstructions six-sevenths go down, but one-seventh comes through\nwith the glory of victory upon its face.\n\nLight comes in undulations to the eye, as tones of sound to the\near. Must not light also sing? The lowest tone we can hear is made\nby 16.5 vibrations of air per second; the highest, so shrill and\n\"fine that nothing lives 'twixt it and silence,\" is made by 38,000\nvibrations per second. Between these extremes lie eleven octaves;\nC of the G clef having 258-7/8 vibrations to the second, and its\noctave above 517-1/2. Not that sound vibrations cease [Page 27] at\n38,000, but our organs are not fitted to hear beyond those\nlimitations. If our ears were delicate enough, we could hear even up\nto the almost infinite vibrations of light. In one of those\nsemi-inspirations we find in Shakspeare's works, he says--\n\n \"There's not the smallest orb which thou beholdest,\n  But in his motion like an angel sings,\n  Still quiring to the young-eyed cherubim.\n  Such harmony is in immortal souls;\n  But, whilst this muddy vesture of decay\n  Doth grossly close it in, we cannot hear it.\"\n\nAnd that older poetry which is always highest truth says, \"The\nmorning stars sing together.\" We misconstrued another passage which\nwe could not understand, and did not dare translate as it was written,\ntill science crept up to a perception of the truth that had been\nstanding there for ages, waiting a mind that could take it in.\nNow we read as it is written--\"Thou makest the out-goings of the\nmorning and evening to sing.\" Were our senses fine enough, we could\nhear the separate keynote of every individual star. Stars differ\nin glory and in power, and so in the volume and pitch of their\nsong. Were our hearing sensitive enough, we could hear not only\nthe separate key-notes but the infinite swelling harmony of these\nmyriad stars of the sky, as they pour their mighty tide of united\nanthems in the ear of God:\n\n \"In reason's ear they all rejoice,\n  And utter forth a glorious voice.\n  Forever singing, as they shine,\n  The hand that made us is divine.\"\n\nThis music is not monotonous. Stars draw near each other, and make\na light that is unapproachable by mortals; [Page 28] then the music\nswells beyond our ability to endure. They recede far away, making a\nlight so dim that the music dies away, so near to silence that only\nspirits can perceive it. No wonder God rejoices in his works. They\npour into his ear one ceaseless tide of rapturous song.\n\nOur senses are limited--we have only five, but there is room for\nmany more. Some time we shall be taken out of \"this muddy vesture\nof decay,\" no longer see the universe through crevices of our\nprison-house, but shall range through wider fields, explore deeper\nmysteries, and discover new worlds, hints of which have never yet\nbeen blown across the wide Atlantic that rolls between them and\nmen abiding in the flesh.\n\n_Chemistry of Suns revealed by Light._\n\nWhen we examine the assemblage of colors spread from the white ray\nof sunlight, we do not find red simple red, yellow yellow, etc.,\nbut there is a vast number of fine microscopic lines of various\nlengths, parallel--here near together, there far apart, always the\nsame number and the same relative distance, when the same light\nand prism are used. What new alphabets to new realms of knowledge\nare these! Remember, that what we call colors are only various\nnumbers of vibrations of ether. Remember, that every little group in\nthe infinite variety of these vibrations may be affected differently\nfrom every other group. One number of these is bent by the prism\nto where we see what we call the violet, another number to the\nplace we call red. All of the vibrations are destroyed when they\nstrike a surface we call black. A part of them are destroyed when\n[Page 29] they strike a substance we call colored. The rest are\nreflected, and give the impression of color. In one place on the\nflag of our nation all vibrations are destroyed except the red; in\nanother, all but the blue. Perhaps on that other gorgeous flag, not\nof our country but of our sun, the flag we call the solar spectrum,\nall vibrations are destroyed where these dark lines appear. Perhaps\nthis effect is not produced by the surface upon which the rays fall,\nbut by some specific substance in the sun. This is just the truth.\nLight passing through vapor of sodium has the vibrations that would\nfall on two narrow lines in the yellow utterly destroyed, leaving\ntwo black spaces. Light passing through vapor of burning iron has\nsome four hundred numbers or kinds of vibrations destroyed, leaving\nthat number of black lines; but if the salt or iron be glowing gas,\nin the source of the light itself the same lines are bright instead\nof dark.\n\nThus we have brought to our doors a readable record of the very\nsubstances composing every world hot enough to shine by its own\nlight. Thus, while our flag means all we have of liberty, free as\nthe winds that kiss it, and bright as the stars that shine in it,\nthe flag of the sun means all that it is in constituent elements,\nall that it is in condition.\n\nWe find in our sun many substances known to exist in the earth,\nand some that we had not discovered when the sun wrote their names,\nor rather made their mark, in the spectrum. Thus, also, we find\nthat Betelguese and Algol are without any perceivable indications\nof hydrogen, and Sirius has it in abundance. What a sense of\nacquaintanceship it gives us to look up and recognize [Page 30] the\nstars whose very substance we know! If we were transported thither,\nor beyond, we should not be altogether strangers in an unknown\nrealm.\n\nBut the stars differ in their constituent elements; every ray that\nflashes from them bears in its very being proofs of what they are.\nHence the eye of Omniscience, seeing a ray of light anywhere in\nthe universe, though gone from its source a thousand years, would\nbe able to tell from what orb it originally came.\n\n_Creative Force of Light._\n\nJust above the color vibrations of the unbraided sunbeam, above\nthe violet, which is the highest number our eyes can detect, is\na chemical force; it works the changes on the glass plate in\nphotography; it transfigures the dark, cold soil into woody fibre,\ngreen leaf, downy rose petals, luscious fruit, and far pervasive\nodor; it flushes the wide acres of the prairie with grass and flowers,\nfills the valleys with trees, and covers the hills with corn, a\nsingle blade of which all the power of man could not make.\n\nThis power is also fit and able to survive. The engineer Stephenson\nonce asked Dr. Buckland, \"What is the power that drives that train?\"\npointing to one thundering by. \"Well, I suppose it is one of your\nbig engines.\" \"But what drives the engine?\" \"Oh, very likely a canny\nNewcastle driver.\" \"No, sir,\" said the engineer, \"it is sunshine.\"\nThe doctor was too dull to take it in. Let us see if we can trace\nsuch an evident effect to that distant cause. Ages ago the warm\nsunshine, falling on the scarcely lifted hills of Pennsylvania,\ncaused the reedy vegetation to grow along the banks of [Page 31]\nshallow seas, accumulated vast amounts of this vegetation, sunk it\nbeneath the sea, roofed it over with sand, compacted the sand into\nrock, and changed this vegetable matter--the products of the\nsunshine--into coal; and when it was ready, lifted it once more, all\ngarnered for the use of men, roofed over with mighty mountains. We\nmine the coal, bring out the heat, raise the steam, drive the train,\nso that in the ultimate analyses it is sunshine that drives the\ntrain. These great beds of coal are nothing but condensed\nsunshine--the sun's great force, through ages gone, preserved for\nour use to-day. And it is so full of force that a piece of coal that\nwill weigh three pounds (as big as a large pair of fists) has as\nmuch power in it as the average man puts into a day's work. Three\ntons of coal will pump as much water or shovel as much sand as the\naverage man will pump or shovel in a lifetime; so that if a man\nproposes to do nothing but work with his muscles, he had better dig\nthree tons of coal and set that to do his work and then die, because\nhis work will be better done, and without any cost for the\nmaintenance of the doer.\n\nCome down below the color vibrations, and we shall find that those\nwhich are too infrequent to be visible, manifest as heat. Naturally\nthere will be as many different kinds of heat as tints of color,\nbecause there is as great a range of numbers of vibration. It is\nour privilege to sift them apart and sort them over, and find what\nkinds are best adapted to our various uses.\n\nTake an electric lamp, giving a strong beam of light and heat, and\nwith a plano-convex lens gather it into a single beam and direct\nit upon a thermometer, twenty feet away, that is made of glass\nand filled with air. The [Page 32] expansion or contraction of this\nair will indicate the varying amounts of heat. Watch your\nair-thermometer, on which the beam of heat is pouring, for the\nresult. There is none. And yet there is a strong current of heat\nthere. Put another kind of test of heat beyond it and it appears;\ncoat the air-thermometer with a bit of black cloth, and that will\nabsorb heat and reveal it. But why not at first? Because the glass\nlens stops all the heat that can affect glass. The twenty feet of\nair absorbs all the heat that affects air, and no kind of heat is\nleft to affect an instrument made of glass and air; but there are\nkinds of heat enough to affect instruments made of other things.\n\nA very strong current of heat may be sent right through the heart\nof a block of ice without melting the ice at all or cooling off\nthe heat in the least. It is done in this way: Send the beam of\nheat through water in a glass trough, and this absorbs all the heat\nthat can affect water or ice, getting itself hot, and leaving all\nother kinds of heat to go through the ice beyond; and appropriate\ntests show that as much heat comes out on the other side as goes\nin on this side, and it does not melt the ice at all. Gunpowder\nmay be exploded by heat sent through ice. Dr. Kane, years ago,\nmade this experiment. He was coming down from the north, and fell\nin with some Esquimaux, whom he was anxious to conciliate. He said\nto the old wizard of the tribe, \"I am a wizard; I can bring the\nsun down out of the heavens with a piece of ice.\" That was a good,\ndeal to say in a country where there was so little sun. \"So,\" he\nwrites, \"I took my hatchet, chipped a small piece of ice into the\nform of a double-convex lens, [Page 33] smoothed it with my warm\nhands, held it up to the sun, and, as the old man was blind, I\nkindly burned a blister on the back of his hand to show him I could\ndo it.\"\n\nThese are simple illustrations of the various kinds of heat. The\nbest furnace or stove ever invented consumes fifteen times as much\nfuel to produce a given amount of heat as the furnace in our bodies\nconsumes to produce a similar amount. We lay in our supplies of\ncarbon at the breakfast, dinner, and supper table, and keep ourselves\nwarm by economically burning it with the oxygen we breathe.\n\nHeat associated with light has very different qualities from that\nwhich is not. Sunlight melts ice in the middle, bottom, and top at\nonce. Ice in the spring-time is honey-combed throughout. A piece\nof ice set in the summer sunshine crumbles into separate crystals.\nDark heat only melts the surface.\n\nNearly all the heat of the sun passes through glass without hinderance;\nbut take heat from white-hot platinum and only seventy-six per cent.\nof it goes through glass, twenty-four per cent. being so constituted\nthat it cannot pass with facility. Of heat from copper at 752\u00b0\nonly six per cent. can go through glass, the other ninety-four per\ncent. being absorbed by it.\n\nThe heat of the sun beam goes through glass without [Page 34] any\nhinderance whatever. It streams into the room as freely as if there\nwere no glass there. But what if the furnace or stove heat went\nthrough glass with equal facility? We might as well try to heat our\nrooms with the window-panes all out, and the blast of winter\nsweeping through them.\n\nThe heat of the sun, by its intense vibrations, comes to the earth\ndowered with a power which pierces the miles of our atmosphere,\nbut if our air were as pervious to the heat of the earth, this\nheat would flyaway every night, and our temperature would go down\nto 200\u00b0 below zero. This heat comes with the light, and then,\ndissociated from it, the number of its vibrations lessened, it is\nrobbed of its power to get away, and remains to work its beneficent\nends for our good.\n\nWorlds that are so distant as to receive only 1/1000 of the heat\nwe enjoy, may have atmospheres that retain it all. Indeed it is\nprobable that Mars, that receives but one-quarter as much heat\nas the earth, has a temperature as high as ours. The poet drew on\nhis imagination when he wrote:\n\n  \"Who there inhabit must have other powers,\n   Juices, and veins, and sense and life than ours;\n   One moment's cold like theirs would pierce the bone,\n   Freeze the heart's-blood, and turn us all to stone.\"\n\nThe power that journeys along the celestial spaces in the flashing\nsunshine is beyond our comprehension. It accomplishes with ease\nwhat man strives in vain to do with all his strength. At West Point\nthere are some links of a chain that was stretched across the river\nto prevent British ships from ascending; these links were made\nof two-and-a-quarter-inch iron. A powerful locomotive might tug\nin vain at one of them and not stretch it the thousandth part of\nan inch. But the heat of a single gas-burner, that glows with the\npreserved sunlight of other ages, when suitably applied to the\nlink, stretches it with ease; such enormous power has a little\nheat. There is a certain iron bridge across the Thames at London,\nresting on arches. The warm sunshine, acting [Page 35] upon the\niron, stations its particles farther and farther apart. Since the\nbottom cannot give way the arches must rise in the middle. As they\nbecome longer they lift the whole bridge, and all the thundering\nlocomotives and miles of goods-trains cannot bring that bridge down\nagain until the power of the sunshine has been withdrawn. There is\nBunker Hill Monument, thirty-two feet square at the base, with an\nelevation of two hundred and twenty feet. The sunshine of every\nsummer's day takes hold of that mighty pile of granite with its\na\u00ebrial fingers, lengthens the side affected, and bends the whole\ngreat mass as easily as one would bend a whipstock. A few years ago\nwe hung a plummet from the top of this monument to the bottom. At 9\nA.M. it began to move toward the west; at noon it swung round toward\nthe north; in the afternoon it went east of where it first was, and\nin the night it settled back to its original place.\n\nThe sunshine says to the sea, held in the grasp of gravitation,\n\"Rise from your bed! Let millions of tons of water fly on the wings\nof the viewless air, hundreds of miles to the distant mountains,\nand pour there those millions of tons that shall refresh a whole\ncontinent, and shall gather in rivers fitted to bear the commerce\nand the navies of nations.\" Gravitation says, \"I will hold every\nparticle of this ocean as near the centre of the earth as I can.\"\nSunshine speaks with its word of power, and says, \"Up and away!\"\nAnd in the wreathing mists of morning these myriads of tons rise\nin the air, flyaway hundreds of miles, and supply all the Niagaras,\nMississippis and Amazons of earth. The sun says to the earth, wrapped\nin the mantle of winter, [Page 36] \"Bloom again;\" and the snows\nmelt, the ice retires, and vegetation breaks forth, birds sing, and\nspring is about us.\n\nThus it is evident that every force is constitutionally arranged\nto be overcome by a higher, and all by the highest. Gravitation of\nearth naturally and legitimately yields to the power of the sun's\nheat, and then the waters fly into the clouds. It as naturally\nand legitimately yields to the power of mind, and the waters of the\nRed Sea are divided and stand \"upright as an heap.\" Water naturally\nbursts into flame when a bit of potassium is thrown into it, and\nas naturally when Elijah calls the right kind of fire from above.\nWhat seems a miracle, and in contravention of law, is only the\nconstitutional exercise of higher force over forces organized to\nbe swayed. If law were perfectly rigid, there could be but one\nforce; but many grades exist from cohesion to mind and spirit.\nThe highest forces are meant to have victory, and thus give the\nhighest order and perfectness.\n\nAcross the astronomic spaces reach all these powers, making creation\na perpetual process rather than a single act. It almost seems as\nif light, in its varied capacities, were the embodiment of God's\ncreative power; as if, having said, \"Let there be light,\" he need do\nnothing else, but allow it to carry forward the creative processes\nto the end of time. It was Newton, one of the earliest and most\nacute investigators in this study of light, who said, \"I seem to\nhave wandered on the shore of Truth's great ocean, and to have\ngathered a few pebbles more beautiful than common; but the vast\nocean itself rolls before me undiscovered and unexplored.\"\n\n[Page 37]\nEXPERIMENTS WITH LIGHT.\n\nA light set in a room is seen from every place; hence light streams\nin every possible direction. If put in the centre of a hollow sphere,\nevery point of the surface will be equally illumined. If put in\na sphere of twice the diameter, the same light will fall on all\nthe larger surface. The surfaces of spheres are as the squares\nof their diameters; hence, in the larger sphere the surface is\nillumined only one-quarter as much as the smaller. The same is true\nof large and small rooms. In Fig. 7 it is apparent that the light\nthat falls on the first square is spread, at twice the distance,\nover the second square, which is four times as large, and at three\ntimes the distance over nine times the surface. The varying amount\nof light received by each planet is also shown in fractions above\neach world, the amount received by the earth being 1.\n\n[Illustration: Fig. 7.]\n\n[Illustration: Fig. 8.--Measuring Intensities of Light.]\n\nThe intensity of light is easily measured. Let two lights of different\nbrightness, as in Fig. 8, cast shadows on the same screen. Arrange\nthem as to distance so that both shadows shall be equally dark.\nLet them fall side by side, and study them carefully. Measure the\nrespective distances. Suppose one is twenty inches, the other forty.\nLight varies as the square [Page 38] of the distance: the square of\n20 is 400, of 40 is 1600. Divide 1600 by 400, and the result is that\none light is four times as bright as the other.\n\n[Illustration: Fig. 9.--Reflection and Diffusion of Light.]\n\nLight can be handled, directed, and bent, as well as iron bars.\nDarken a room and admit a beam of sunlight through a shutter, or\na ray of lamp-light through the key-hole. If there is dust in the\nroom it will be observed that light goes in straight lines. Because\nof this men are able to arrange houses and trees in rows, the hunter\naims his rifle correctly, and the astronomer projects straight\nlines to infinity. Take a hand-mirror, or better, a piece of glass\ncoated on one side with black varnish, and you can send your ray\nanywhere. By using two mirrors, or having an assistant and using\nseveral, you can cause a ray of light to turn as many corners as you\nplease. I once saw Mr. Tyndall send a ray into a glass jar filled\nwith smoke (Fig. 9). Admitting a slender ray through a small hole in\na card over the mouth, one ray appeared; removing the cover, the\nwhole jar was luminous; as the smoke disappeared in spots cavities\nof darkness appeared. Turn the same ray into a tumbler of water,\n[Page 39]\nit becomes faintly visible; stir into it a teaspoonful of milk, then\nturn in the ray of sunlight, and it glows like a lamp, illuminating\nthe whole room. These experiments show how the straight rays of\nthe sun are diffused in every direction over the earth.\n\nSet a small light near one edge of a mirror; then, by putting the\neye near the opposite edge, you see almost as many flames as you\nplease from the multiplied reflections. How can this be accounted\nfor?\n\nInto your beam of sunlight, admitted through a half-inch hole,\nput the mirror at an oblique angle; you can arrange it so as to\nthrow half a dozen bright spots on the opposite wall.\n\n[Illustration: Fig. 10.--Manifold Reflections.]\n\nIn Fig. 10 the sunbeam enters at A, and, striking the mirror _m_\nat _a_, is partly reflected to 1 on the wall, and partly enters\nthe glass, passes through to the silvered back at B, and is totally\nreflected to _b_, where it again divides, some of it going to the\nwall at 2, and the rest, continuing to make the same reflections\nand divisions, causes spots 3, 4, 5, etc. The brightest spot is\nat No.2, because the silvered glass at B is the best reflector\nand has the most light.\n\nWhen the discovery of the moons of Mars was announced in 1877,\nit was also widely published that they could be seen by a mirror.\nOf course this is impossible. The point of light mistaken for the\nmoon in this secondary reflection was caused by holding the mirror\nin an oblique position.\n\nTake a small piece of mirror, say an inch in surface, and putting\nunder it three little pellets of wax, putty, or clay, set it on\nthe wrist, with one of the pellets on the pulse. Hold the mirror\nsteadily in the beam of light, and the frequency and prominence of\neach pulse-beat will be indicated by the tossing spot of light on\nthe wall. If the operator becomes excited the fact will be evident\nto all observers.\n\n[Illustration: Fig. 11.]\n\nPlace a coin in a basin (Fig. 11), and set it so that the rim will\nconceal the coin from the eye. Pour in water, and the coin will\n[Page 40] appear to rise into sight. When light passes from a medium\nof one density to a medium of another, its direction is changed.\nThus a stick in water seems bent. Ships below the horizon are\nsometimes seen above, because of the different density of the layers\nof air.\n\nThus light coming from the interstellar spaces, and entering our\natmosphere, is bent down more and more by its increasing density.\nThe effect is greatest when the sun or star is near the horizon,\nnone at all in the zenith. This brings the object into view before\nit is risen. Allowance for this displacement is made in all delicate\nastronomical observations.\n\n[Illustration: Fig. 12.--Atmospherical Refraction.]\n\nNotice on the floor the shadow of the window-frames. The glass\nof almost every window is so bent as to turn the sunlight aside\nenough to obliterate some of the shadows or increase their thickness.\n\nDECOMPOSITION OF LIGHT.\n\nAdmit the sunbeam through a slit one inch long and one-twentieth\nof an inch wide. Pass it through a prism. Either purchase one or\nmake it of three plain pieces of glass one and a half inch wide\nby six inches long, fastened together in triangular shape--fasten\nthe edges with hot wax and fill it with water; then on a screen\nor wall you will have the colors of the rainbow, not merely seven\nbut seventy, if your eyes are sharp enough.\n\nTake a bit of red paper that matches the red color of the spectrum.\nMove it along the line of colors toward the violet. In the orange\nit is dark, in the yellow darker, in the green and all beyond,\nblack. That is because there are no more red rays to be reflected\nby it. So a green object is true to its color only in the green\nrays, and black elsewhere. All these colors may be recombined by\na second prism into white light.\n\n\n\n\n[Page 41]\nIII.\n\nASTRONOMICAL INSTRUMENTS.\n\n  \"The eyes of the Lord are in every place.\"--_Proverbs_ xv. 3.\n\n[Page 42]\n\"Man, having one kind of an eye given him by his Maker, proceeds\nto construct two other kinds. He makes one that magnifies invisible\nobjects thousands of times, so that a dull razor-edge appears as\nthick as three fingers, until the amazing beauty of color and form\nin infinitesimal objects is entrancingly apparent, and he knows that\nGod's care of least things is infinite. Then he makes the other kind\nfour or six feet in diameter, and penetrates the immensities of space\nthousands of times beyond where his natural eye can pierce, until he\nsees that God's immensities of worlds are infinite also.\"--BISHOP\nFOSTER.\n\n\n\n\n[Page 43]\nIII.\n\n_THE TELESCOPE._\n\nFrequent allusion has been made in the previous chapter to discovered\nresults. It is necessary to understand more clearly the process by\nwhich such results have been obtained. Some astronomical instruments\nare of the simplest character, some most delicate and complex.\nWhen a man smokes a piece of glass, in order to see an eclipse\nof the sun, he makes a simple instrument. Ferguson, lying on his\nback and slipping beads on a string at a certain distance above\nhis eye, measured the relative distances of the stars. The use\nof more complex instruments commenced when Galileo applied the\ntelescope to the heavens. He cannot be said to have invented the\ntelescope, but he certainly constructed his own without a pattern,\nand used it to good purpose. It consists of a lens, O B (Fig. 13),\nwhich acts as a multiple prism to bend all the rays to one point\nat R. Place the eye there, and it receives as much light as if it\nwere as large as the lens O B. The rays, however, are convergent,\nand the point difficult to [Page 44] find. Hence there is placed at\nR a concave lens, passing through which the rays emerge in parallel\nlines, and are received by the eye. Opera-glasses are made upon\nprecisely this principle to-day, because they can be made\nconveniently short.\n\n[Illustration: Fig. 13.--Refracting Telescope.]\n\nIf, instead of a concave lens at R, converting the converging rays\ninto parallel ones, we place a convex or magnifying lens, the minute\nimage is enlarged as much as an object seems diminished when the\ntelescope is reversed. This is the grand principle of the refracting\ntelescope. Difficulties innumerable arise as we attempt to enlarge\nthe instruments. These have been overcome, one after another, until\nit is now felt that the best modern telescope, with an object lens\nof twenty-six inches, has fully reached the limit of optical power.\n\n_The Reflecting Telescope_.\n\nThis is the only kind of instrument differing radically from the\nrefracting one already described. It receives the light in a concave\nmirror, M (Fig. 14), which reflects it to the focus F, producing the\nsame result as the lens of the refracting telescope. Here a mirror\nmay be placed obliquely, reflecting the image at right angles to the\neye, outside the tube, in which case it is called the Newtonian\ntelescope; or a mirror at R may be placed perpendicularly, and send\nthe rays through [Page 45] an opening in the mirror at M. This form\nis called the Gregorian telescope. Or the mirror M may be slightly\ninclined to the coming rays, so as to bring the point F entirely\noutside the tube, in which case it is called the Herschelian\ntelescope. In either case the image may be magnified, as in the\nrefracting telescope.\n\n[Illustration: Fig. 14.--Reflecting Telescope.]\n\nReflecting telescopes are made of all sizes, up to the Cyclopean\neye of the one constructed by Lord Rosse, which is six feet in\ndiameter. The form of instrument to be preferred depends on the\nuse to which it is to be put. The loss of light in passing through\nglass lenses is about two-tenths. The loss by reflection is often\none-half. In view of this peculiarity and many others, it is held\nthat a twenty-six-inch refractor is fully equal to any six-foot\nreflector.\n\nThe mounting of large telescopes demands the highest engineering\nability. The whole instrument, with its vast weight of a twenty-six-inch\nglass lens, with its accompanying tube and appurtenances, must be\npointed as nicely as a rifle, and held as steadily as the axis\nof the globe. To give it the required steadiness, the foundation\non which it is placed is sunk deep in the earth, far from rail or\nother roads, and no part of the observatory is allowed to touch\nthis support. When a star is once found, the earth swiftly rotates\nthe telescope away from it, and it passes out of the field. To\navoid this, clock-work is so arranged that the great telescope\nfollows the star by the hour, if required. It will take a star at\nits eastern rising, and hold it constantly in view while it climbs\nto the meridian and sinks in the west (Fig. 15). The reflector\ndemands still more difficult engineering. That of Lord Rosse has\na metallic mirror [Page 46] weighing six tons, a tube forty feet\nlong, which, with its appurtenances, weighs seven tons more. It\nmoves between two walls only 10\u00b0 east and west. The new Paris\nreflector (Fig. 16) has a much wider range of movement.\n\n[Illustration: Fig. 15.--Cambridge Equatorial.]\n\n[Illustration: Fig. 16.--New Paris Reflector.]\n\n_The Spectroscope._\n\nA spectrum is a collection of the colors which are dispersed by\na prism from any given light. If it is sunlight, it is a solar\nspectrum; if the source of light is a [Page 49] star, candle,\nglowing metal, or gas, it is the spectrum of a star, candle, glowing\nmetal, or gas. An instrument to see these spectra is called a\nspectroscope. Considering the infinite variety of light, and its\neasy modification and absorption, we should expect an immense number\nof spectra. A mere prism disperses the light so imperfectly that\ndifferent orders of vibrations, perceived as colors, are mingled. No\neye can tell where one commences or ends. Such a spectrum is said to\nbe impure. What we want is that each point in the spectrum should be\nmade of rays of the same number of vibrations. As we can let only a\nsmall beam of light pass through the prism, in studying celestial\nobjects with a telescope and spectroscope we must, in every\ninstance, contract the aperture of the instrument until we get only\na small beam of light. In order to have the colors thoroughly\ndispersed, the best instruments pass the beam of light through a\nseries of prisms called a battery, each one spreading farther the\ncolors which the previous ones had spread. In Fig. 17 the ray is\nseen entering through the telescope A, which renders the rays\nparallel, and passing [Page 50] through the prisms out to telescope\nB, where the spectrum can be examined on the retina of the eye for a\nscreen. In order to still farther disperse the rays, some batteries\nreceive the ray from the last prism at O upon an oblique mirror,\nsend it up a little to another, which delivers it again to the prism\nto make its journey back again through them all, and come out to be\nexamined just above where it entered the first prism.\n\n[Illustration: Fig. 17.--Spectroscope, with Battery of Prisms.]\n\nAttached to the examining telescope is a diamond-ruled scale of glass,\nenabling us to fix the position of any line with great exactness.\n\n[Illustration: Fig. 18.--Spectra of glowing Hydrogen and the Sun.]\n\nIn Fig. 18 is seen, in the lower part, a spectrum of the sun, with\nabout a score of its thousands of lines made evident. In the upper\npart is seen the spectrum of bright lines given by glowing hydrogen\ngas. These lines are given by no other known gas; they are its\nautograph. It is readily observed that they precisely correspond\nwith certain dark lines in the solar spectrum. Hence we easily\nknow that a glowing gas gives the same bright lines that it absorbs\nfrom the light of another source passing through it--that is, glowing\ngas gives out the same rays of light that it absorbs when it is\nnot glowing.\n\nThe subject becomes clearer by a study of the chromolithic plate.\nNo. 1 represents the solar spectrum, with a few of its lines on an\naccurately graduated scale. [Page 51] No.3 shows the bright line of\nglowing sodium, and, corresponding to a dark line in the solar\nspectrum, shows the presence of salt in that body. No. 2 shows that\npotassium has some violet rays, but not all; and there being no dark\nline to correspond in the solar spectrum, we infer its absence from\nthe sun. No.6 shows the numerous lines and bands of barium--several\nred, orange, yellow, and four are very bright green ones. The lines\ngiven by any volatilized substances are always in the same place on\nthe scale.\n\nA patient study of these signs of substances reveals, richer results\nthan a study of the cuniform characters engraved on Assyrian slabs;\nfor one is the handwriting of men, the other the handwriting of\nGod.\n\nOne of the most difficult and delicate problems solved by the\nspectroscope is the approach or departure of a light-giving body\nin the line of sight. Stand before a locomotive a mile away, you\ncannot tell whether it approaches or recedes, yet it will dash by\nin a minute. How can the movements of the stars be comprehended\nwhen they are at such an immeasurable distance?\n\nIt can best be illustrated by music. The note C of the G clef is\nmade by two hundred and fifty-seven vibrations of air per second.\nTwice as many vibrations per second would give us the note C an octave\nabove. Sound travels at the rate of three hundred and sixty-four\nyards per second. If the source of these two hundred and fifty-seven\nvibrations could approach us at three hundred and sixty-four yards\nper second, it is obvious that twice as many waves would be put\ninto a given space, and we should hear the upper C when only waves\nenough were made for the lower C. The same [Page 52] result would\nappear if we carried our ear toward the sound fast enough to take up\ntwice as many valves as though we stood still. This is apparent to\nevery observer in a railway train. The whistle of an approaching\nlocomotive gives one tone; it passes, and we instantly detect\nanother. Let two trains, running at a speed of thirty-six yards a\nsecond, approach each other. Let the whistle of one sound the note\nE, three hundred and twenty-three vibrations per second. It will be\nheard on the other as the note G, three hundred and eighty-eight\nvibrations per second; for the speed of each train crowds the\nvibrations into one-tenth less room, adding 32+ vibrations per\nsecond, making three hundred and eighty-eight in all. The trains\npass. The vibrations are put into one-tenth more space by the\nwhistle making them, and the other train allows only nine-tenths of\nwhat there are to overtake the ear. Each subtracts 32+ vibrations\nfrom three hundred and twenty-three, leaving only two hundred and\nfifty-eight, which is the note C. Yet the note E was constantly\nuttered.\n\n[Illustration: 1. Solar Spectrum. 2. Spectrum of Potassium. 3.\nSpectrum of Sodium. 4. Spectrum of Strontium. 5. Spectrum of Calcium.\n6. Spectrum of Barium.]\n\nIf a source of light approach or depart, it will have a similar\neffect on the light waves. How shall we detect it? If a star approach\nus, it puts a greater number of waves into an inch, and shortens their\nlength. If it recedes, it increases the length of the wave--puts\na less number into an inch. If a body giving only the number of\nvibrations we call green were to approach sufficiently fast, it\nwould crowd in vibrations enough to appear what we call blue, indigo,\nor even violet, according to its speed. If it receded sufficiently\nfast, it would leave behind it only vibrations enough to fill up\n[Page 53] the space with what we call yellow, orange, or red,\naccording to its speed; yet it would be green, and green only, all\nthe time. But how detect the change? If red waves are shortened they\nbecome orange in color; and from below the red other rays, too far\napart to be seen by the eye, being shortened, become visible as red,\nand we cannot know that anything has taken place. So, if a star\nrecedes fast enough, violet vibrations being lengthened become\nindigo; and from above the violet other rays, too short to be seen,\nbecome lengthened into visible violet, and we can detect no movement\nof the colors. The dark lines of the spectrum are the cutting out of\nrays of definite wave-lengths. If the color spectrum moves away,\nthey move with it, and away from their proper place in the ordinary\nspectrum. If, then, we find them toward the red end, the star is\nreceding; if toward the violet end, it is approaching. Turn the\ninstrument on the centre of the sun. The dark lines take their\nappropriate place, and are recognized on the ruled scale. Turn it on\none edge, that is approaching us one and a quarter miles a second by\nthe revolution of the sun on its axis, the spectral lines move\ntoward the violet end; turn the spectroscope toward the other edge\nof the sun, it is receding from us one and a quarter miles a second\nby reason of the axial revolution, and the spectral lines move\ntoward the red end. Turn it near the spots, and it reveals the\nmighty up-rush in one place and the down-rush in another of one\nhundred miles a second. We speak of it as an easy matter, but it is\na problem of the greatest delicacy, almost defying the mind of man\nto read the movements of matter.\n\nIt should be recognized that Professor Young, of [Page 54]\nPrinceton, is the most successful operator in this recent realm of\nscience. He already proposes to correct the former estimate of the\nsun's axial revolutions, derived from observing its spots, by the\nsurer process of observing accelerated and retarded light.\n\nWithin a very few years this wonderful instrument, the spectroscope,\nhas made amazing discoveries. In chemistry it reveals substances\nnever known before; in analysis it is delicate to the detection of\nthe millionth of a grain. It is the most deft handmaid of chemistry,\nthe arts, of medical science, and astronomy. It tells the chemical\nconstitution of the sun, the movements taking place, the nature of\ncomets, and nebul\u00e6. By the spectroscope we know that the atmospheres\nof Venus and Mars are like our own; that those of Jupiter and Saturn\nare very unlike; it tells us which stars approach and which recede,\nand just how one star differeth from another in glory and substance.\n\nIn the near future we shall have the brilliant and diversely colored\nflowers of the sky as well classified into orders and species as\nare the flowers of the earth.\n\n\n\n\n[Page 55]\nIV.\n\nCELESTIAL MEASUREMENTS.\n\n\"Who hath measured the waters in the hollow of his hand, and meted\nout heaven with the span? Mine hand also hath laid the foundation\nof the earth, and my right hand hath spanned the heavens.\"--_Isa._\nxl. 12; xlviii. 13.\n\n[Page 56]\n \"Go to yon tower, where busy science plies\n  Her vast antenn\u00e6, feeling thro' the skies;\n  That little vernier, on whose slender lines\n  The midnight taper trembles as it shines,\n  A silent index, tracks the planets' march\n  In all their wanderings thro' the ethereal arch,\n  Tells through the mist where dazzled Mercury burns,\n  And marks the spot where Uranus returns.\n\n \"So, till by wrong or negligence effaced,\n  The living index which thy Maker traced\n  Repeats the line each starry virtue draws\n  Through the wide circuit of creation's laws;\n  Still tracks unchanged the everlasting ray\n  Where the dark shadows of temptation stray;\n  But, once defaced, forgets the orbs of light,\n  And leaves thee wandering o'er the expanse of night.\"\n      OLIVER WENDELL HOLMES.\n\n\n\n\n[Page 57]\nIV.\n\n_CELESTIAL MEASUREMENTS._\n\nWe know that astronomy has what are called practical uses. If a\nship had been driven by Euroclydon ten times fourteen days and\nnights without sun or star appearing, a moment's glance into the\nheavens from the heaving deck, by a very slightly educated sailor,\nwould tell within one hundred yards where he was, and determine\nthe distance and way to the nearest port. We know that, in all\nfinal and exact surveying, positions must be fixed by the stars.\nEarth's landmarks are uncertain and easily removed; those which\nwe get from the heavens are stable and exact.\n\nIn 1878 the United States steam-ship _Enterprise_ was sent to survey\nthe Amazon. Every night a \"star party\" went ashore to fix the exact\nlatitude and longitude by observations of the stars. Our real landmarks\nare not the pillars we rear, but the stars millions of miles away.\nAll our standards of time are taken from the stars; every railway\ntrain runs by their time to avoid collision; by them all factories\nstart and stop. Indeed, we are ruled by the stars even more than\nthe old astrologers imagined.\n\nMan's finest mechanism, highest thought, and broadest exercise\nof the creative faculty have been inspired by astronomy. No other\ninstruments approximate in delicacy those which explore the heavens;\nno other [Page 58] system of thought can draw such vast and certain\nconclusions from its premises. \"Too low they build who build beneath\nthe stars;\" we should lay our foundations in the skies, and then\nbuild upward.\n\nWe have been placed on the outside of this earth, instead of the\ninside, in order that we may look abroad. We are carried about,\nthrough unappreciable distance, at the inconceivable velocity of\none thousand miles a minute, to give us different points of vision.\nThe earth, on its softly-spinning axle, never jars enough to unnest\na bird or wake a child; hence the foundations of our observatories\nare firm, and our measurements exact. Whoever studies astronomy,\nunder proper guidance and in the right spirit, grows in thought\nand feeling, and becomes more appreciative of the Creator.\n\n_Celestial Movements._\n\nLet it not be supposed that a mastery of mathematics and a finished\neducation are necessary to understand the results of astronomical\nresearch. It took at first the highest power of mind to make the\ndiscoveries that are now laid at the feet of the lowliest. It took\nsublime faith, courage, and the results of ages of experience in\nnavigation, to enable Columbus to discover that path to the New\nWorld which now any little boat can follow. Ages of experience\nand genius are stored up in a locomotive, but quite an unlettered\nman can drive it. It is the work of genius to render difficult\nmatters plain, abstruse thoughts clear.\n\n[Illustration: Fig. 19.]\n\nA brief explanation of a few terms will make the principles of\nworld inspection easily understood. Imagine a perfect circle thirty\nfeet in diameter--that is, create [Page 59] one (Fig. 19). Draw\nthrough it a diameter horizontally, another perpendicularly. The\nangles made by the intersecting lines are each said to be ninety\ndegrees, marked thus \u00b0. The arc of a circle included between any two\nof the lines is also 90\u00b0. Every circle, great or small, is divided\ninto these 360\u00b0. If the sun rose in the east and came to the zenith\nat noon, it would have passed 90\u00b0. When it set in the west it would\nhave traversed half the circle, or 180\u00b0. In Fig. 20 the angle of the\nlines measured on the graduated arc is 10\u00b0. The mountain is 10\u00b0\nhigh, the world 10\u00b0 in diameter, the comet moves 10\u00b0 a day, the\nstars are 10\u00b0 apart. The height of the mountain, the diameter of the\nworld, the velocity of the comet, and the distance between the\nstars, depend on the distance of each from the point of sight. Every\ndegree is divided into 60 minutes (marked '), and every minute into\n60 seconds (marked \").\n\n[Illustration: Fig. 20.--Illustration of Angles.]\n\nImagine yourself inside a perfect sphere one hundred feet in diameter,\nwith the interior surface above, around, and below studded with\nfixed bright points like stars. The familiar constellations of\nnight might be blazoned there in due proportion.\n\nIf this star-sprent sphere were made to revolve once in twenty-four\nhours, all the stars would successively [Page 60] pass in review.\nHow easily we could measure distances between stars, from a certain\nfixed meridian, or the equator! How easily we could tell when any\nparticular star would culminate! It is as easy to take all these\nmeasurements when our earthly observatory is steadily revolved\nwithin the sphere of circumambient stars. Stars can be mapped as\nreadily as the streets of a great city. Looking down on it in the\nnight, one could trace the lines of lighted streets, and judge\nsomething of its extent and regularity. But the few lamps of evening\nwould suggest little of the greatness of the public buildings, the\nmagnificent enterprise and commerce of its citizens, or the\nintelligence of its scholars. Looking up to the lamps of the\ncelestial city, one can judge something of its extent and\nregularity; but they suggest little of the magnificence of the many\nmansions.\n\nStars are reckoned as so many degrees, minutes, and seconds from\neach other, from the zenith, or from a given meridian, or from the\nequator. Thus the stars called the Pointers, in the Great Bear,\nare 5\u00b0 apart; the nearest one is 29\u00b0 from the Pole Star, which is\n39\u00b0 56' 29\" above the horizon at Philadelphia. In going to England\nyou creep up toward the north end of the earth, till the Pole Star\nis 54\u00b0 high. It stays near its place among the stars continually,\n\n \"Of whose true-fixed and resting quality\n  There is no fellow in the firmament.\"\n\n_How to Measure._\n\nSuppose a telescope, fixed to a mural circle, to revolve on an axis,\nas in Fig. 21; point it horizontally at a star; [Page 61] turn it up\nperpendicular to another star. Of course the two stars are 90\u00b0\napart, and the graduated scale, which is attached to the outer edge\nof the circle, shows a revolution of a quarter circle, or 90\u00b0, But a\nperfect accuracy of measurement must be sought; for to mistake the\nbreadth of a hair, seen at the distance of one hundred and\ntwenty-five feet, would cause an error of 3,000,000 miles at the\ndistance of the sun, and immensely more at the distance of the\nstars. The correction of an inaccuracy of no greater magnitude than\nthat has reduced our estimate of the distance of our sun 3,000,000\nmiles.\n\n[Illustration: Fig. 21.--Mural Circle.]\n\nConsider the nicety of the work. Suppose the graduated scale to\nbe thirty feet in circumference. Divided into 360\u00b0, each would\nbe one inch long. Divide each degree into 60', each one is 1/60\nof an inch long. It takes good eyesight to discern it. But each\nminute must be [Page 62] divided into 60\", and these must not only\nbe noted, but even tenths and hundredths of seconds must be\ndiscerned. Of course they are not seen by the naked eye; some\nmechanical contrivance must be called in to assist. A watch loses\ntwo minutes a week, and hence is unreliable. It is taken to a\nwatch-maker that every single second may be quickened 1/20160 part\nof itself. Now 1/20000 part of a second would be a small interval of\ntime to measure, but it must be under control. If the temperature of\na summer morning rises ten or twenty degrees we scarcely notice it;\nbut the magnetic tastimeter measures 1/5000 of a degree.\n\nCome to earthly matters. In 1874, after nearly twenty-eight years'\nwork, the State of Massachusetts opened a tunnel nearly five miles\nlong through the Hoosac Mountains. In the early part of the work\nthe engineers sunk a shaft near the middle 1028 feet deep. Then the\nquestion to be settled was where to go so as to meet the approaching\nexcavations from the east and west. A compass could not be relied\non under a mountain. The line must be mechanically fixed. A little\ndivergence at the starting-point would become so great, miles away,\nthat the excavations might pass each other without meeting; the\ngrade must also rise toward the central shaft, and fall in working\naway from it; but the lines were fixed with such infinitesimal\naccuracy that, when the one going west from the eastern portal and\nthe one going east from the shaft met in the heart of the mountain,\nthe western line was only one-eighth of an inch too high, and\nthree-sixteenths of an inch too far north. To reach this perfect\nresult they had to triangulate from the eastern portal to distant\n[Page 63] mountain peaks, and thence down the valley to the central\nshaft, and thus fix the direction of the proposed line across the\nmouth of the shaft. Plumb-lines were then dropped one thousand and\ntwenty-eight feet, and thus the line at the bottom was fixed.\n\nThree attempts were made--in 1867, 1870, and 1872--to fix the exact\ntime-distance between Greenwich and Washington. These three separate\nefforts do not differ one-tenth of a second. Such demonstrable results\non earth greatly increase our confidence in similar measurements\nin the skies.\n\n[Illustration: Fig. 22.]\n\nA scale is frequently affixed to a pocket-rule, by which we can\neasily measure one-hundredth of an inch (Fig. 22). The upper and\nlower line is divided into tenths of an inch. Observe the slanting\nline at the right hand. It leans from the perpendicular one-tenth\nof an inch, as shown by noticing where it reaches the top line. When\nit reaches the second horizontal line it has left the perpendicular\none-tenth of that tenth--that is, one-hundredth. The intersection\nmarks 99/100 of an inch from one end, and one-hundredth from the\nother.\n\nWhen division-lines, on measures of great nicety, get too fine\nto be read by the eye, we use the microscope. By its means we are\nable to count 112,000 lines ruled on a glass plate within an inch.\nThe smallest object that can be seen by a keen eye makes an angle\nof 40\", but by putting six microscopes on the scale of the telescope\non the mural circle, we are able to reach an exactness of 0\".1, or\n1/3600 of an inch. This instrument is used to measure the declination\nof stars, or angular [Page 64] distance north or south of the\nequator. Thus a star's place in two directions is exactly fixed.\nWhen the telescope is mounted on two pillars instead of the face of\na wall, it is called a transit instrument. This is used to determine\nthe time of transit of a star over the meridian, and if the transit\ninstrument is provided with a graduated circle it can also be used\nfor the same purposes as the mural circle. Man's capacity to measure\nexactly is indicated in his ascertainment of the length of waves of\nlight. It is easy to measure the three hundred feet distance between\nthe crests of storm-waves in the wide Atlantic; easy to measure the\ndifferent wave-lengths of the different tones of musical sounds. So\nmen measure the lengths of the undulations of light. The shortest is\nof the violet light, 154.84 ten-millionths of an inch. By the\nhorizontal pendulum Professor Root has made 1/36000000 of an inch\napparent.\n\nThe next elements of accuracy must be perfect time and perfect\nnotation of time. As has been said, we get our time from the stars.\nThus the infinite and heavenly dominates the finite and earthly.\nClocks are set to the invariable sidereal time. Sidereal noon is\nwhen we have turned ourselves under the point where the sun crosses\nthe equator in March, called the vernal equinox. Sidereal clocks\nare figured to indicate twenty-four hours in a day: they tick exact\nseconds. To map stars we wish to know the exact second when they\ncross the meridian, or the north and south line in the celestial\ndome above us. The telescope (Fig. 21, p. 61) swings exactly north\nand south. In its focus a set of fine threads of spider-lines is\nplaced (Fig. 23). The telescope is set just high enough, so that\nby the rolling over of the earth [Page 65] the star will come into\nthe field just above the horizontal thread. The observer notes the\nexact second and tenth of a second when the star reaches each\nvertical thread in the instrument, adds together the times and\ndivides by five to get the average, and the exact time is reached.\n\n[Illustration: Fig. 23.--Transit of a Star noted.]\n\nBut man is not reliable enough to observe and record with sufficient\naccuracy. Some, in their excitement, anticipate its positive passage,\nand some cannot get their slow mental machinery in motion till\nafter it has made the transit. Moreover, men fall into a habit of\nestimating some numbers of tenths of a second oftener than others.\nIt will be found that a given observer will say three tenths or\nseven tenths oftener than four or eight. He is falling into ruts,\nand not trustworthy. General O. M. Mitchel, who had been director\nof the Cincinnati Observatory, once told one of his staff-officers\nthat he was late at an appointment. \"Only a few minutes,\" said the\nofficer, apologetically. \"Sir,\" said the general, \"where I have\nbeen accustomed to work, hundredths of a second are too important\nto be neglected.\" And it is to the rare genius of this astronomer,\nand to others, that we owe the mechanical accuracy that we now\nattain. The clock is made to mark its seconds on paper wrapped\naround a revolving cylinder. Under the observer's fingers is an\nelectric key. This he can touch at the instant of the transit of\nthe star [Page 66] over each wire, and thus put his observation on\nthe same line between the seconds dotted by the clock. Of course\nthese distances can be measured to minute fractional parts of a\nsecond.\n\nBut it has been found that it takes an appreciable time for every\nobserver to get a thing into his head and out of his finger-ends,\nand it takes some observers longer than others. A dozen men, seeing\nan electric spark, are liable to bring down their recording marks\nin a dozen different places on the revolving paper. Hence the time\nthat it takes for each man to get a thing into his head and out\nof his fingers is ascertained. This time is called his personal\nequation, and is subtracted from all of his observations in order to\nget at the true time; so willing are men to be exact about material\nmatters. Can it be thought that moral and spiritual matters have\nno precision? Thus distances east or west from any given star or\nmeridian are secured; those north and south from the equator or\nthe zenith are as easily fixed, and thus we make such accurate\nmaps of the heavens that any movements in the far-off stars--so\nfar that it may take centuries to render the swiftest movements\nappreciable--may at length be recognized and accounted for.\n\n[Illustration: Fig. 24.]\n\nWe now come to a little study of the modes of measuring distances.\nCreate a perfect square (Fig. 24); draw a diagonal line. The square\nangles are 90\u00b0, the divided angles give two of 45\u00b0 each. Now the\nbase A B is equal to the perpendicular A C. Now any point--C, where\na perpendicular, A C, and a diagonal, B C, meet--will be [Page 67]\nas far from A as B is. It makes no difference if a river flows\nbetween A and C, and we cannot go over it; we can measure its\ndistance as easily as if we could. Set a table four feet by eight\nout-doors (Fig. 25); so arrange it that, looking along one end, the\nline of sight just strikes a tree the other side of the river. Go to\nthe other end, and, looking toward the tree, you find the line of\nsight to the tree falls an inch from the end of the table on the\nfarther side. The lines, therefore, approach each other one inch in\nevery four feet, and will come together at a tree three hundred and\neighty-four feet away.\n\n[Illustration: Fig. 25.--Measuring Distances.]\n\n[Illustration: Fig. 26.--Measuring Elevations.]\n\nThe next process is to measure the height or magnitude of objects\nat an ascertained distance. Put two pins in a stick half an inch\napart (Fig. 26). Hold it up two feet from the eye, and let the\nupper pin fall in line with your eye and the top of a distant church\nsteeple, and the lower pin in line with the bottom of the church and\nyour eye. If the church is three-fourths of a mile away, it must\nbe eighty-two feet high; if a mile away, it must be one hundred\nand ten feet high. For if two lines spread [Page 68] one-half an\ninch going two feet, in going four feet they will spread an inch,\nand in going a mile, or five thousand two hundred and eighty feet,\nthey will spread out one-fourth as many inches, viz., thirteen\nhundred and twenty--that is, one hundred and ten feet. Of course\nthese are not exact methods of measurement, and would not be correct\nto a hair at one hundred and twenty-five feet, but they perfectly\nillustrate the true methods of measurement.\n\nImagine a base line ten inches long. At each end erect a perpendicular\nline. If they are carried to infinity they will never meet: will\nbe forever ten inches apart. But at the distance of a foot from\nthe base line incline one line toward the other 63/10000000 of\nan inch, and the lines will come together at a distance of three\nhundred miles. That new angle differs from the former right angle\nalmost infinitesimally, but it may be measured. Its value is about\nthree-tenths of a second. If we lengthen the base line from ten\ninches to all the miles we can command, of course the point of\nmeeting will be proportionally more distant. The angle made by\nthe lines where they come together will be obviously the same as\nthe angle of divergence from a right angle at this end. That angle\nis called the parallax of any body, and is the angle that would\nbe made by two lines coming from that body to the two ends of any\nconventional base, as the semi-diameter of the earth. That that\nangle would vary according to the various distances is easily seen\nby Fig. 27.\n\n[Illustration: Fig. 27.]\n\nLet O P be the base. This would subtend a greater angle seen from\nstar A than from star B. Let B be far enough away, and O P would\nbecome invisible, and B [Page 69] would have no parallax for that\nbase. Thus the moon has a parallax of 57\" with the semi-equatorial\ndiameter of the earth for a base. And the sun has a parallax 8\".85\non the same base. It is not necessary to confine ourselves to right\nangles in these measurements, for the same principles hold true in\nany angles. Now, suppose two observers on the equator should look at\nthe moon at the same instant. One is on the top of Cotopaxi, on the\nwest coast of South America, and one on the west coast of Africa.\nThey are 90\u00b0 apart--half the earth's diameter between them. The one\non Cotopaxi sees it exactly overhead, at an angle of 90\u00b0 with the\nearth's diameter. The one on the coast of Africa sees its angle with\nthe same line to be 89\u00b0 59' 3\"--that is, its parallax is 57\". Try\nthe same experiment on the sun farther away, as is seen in Fig. 27,\nand its smaller parallax is found to be only 8\".85.\n\nIt is not necessary for two observers to actually station themselves\nat two distant parts of the earth in order to determine a parallax.\nIf an observer could go from one end of the base-line to the other,\nhe could determine both angles. Every observer is actually carried\nalong through space by two motions: one is that of the earth's\nrevolution of one thousand miles an hour around the axis; and the\nother is the movement of the earth around the sun of one thousand\nmiles in a minute. Hence we can have the diameter not only of [Page\n70] the earth (eight thousand miles) for a base-line, but the\ndiameter of the earth's orbit (184,000,000 miles), or any part of\nit, for such a base. Two observers at the ends of the earth's\ndiameter, looking at a star at the same instant, would find that it\nmade the same angle at both ends; it has no parallax on so short a\nbase. We must seek a longer one. Observe a certain star on the 21st\nof March; then let us traverse the realms of space for six months,\nat one thousand miles a minute. We come round in our orbit to a\npoint opposite where we were six months ago, with 184,000,000 of\nmiles between the points. Now, with this for a base-line, measure\nthe angles of the same stars: it is the same angle. Sitting in my\nstudy here, I glance out of the window and discern separate bricks,\nin houses five hundred feet away, with my unaided eye; they subtend\na discernible angle. But one thousand feet away I cannot distinguish\nindividual bricks; their width, being only two inches, does not\nsubtend an angle apprehensible to my vision. So at these distant\nstars the earth's enormous orbit, if lying like a blazing ring in\nspace, with the world set on its edge like a pearl, and the sun\nblazing like a diamond in the centre, would all shrink to a mere\npoint. Not quite to a point from the nearest stars, or we should\nnever be able to measure the distance of any of them. Professor Airy\nsays that our orbit, seen from the nearest star, would be the same\nas a circle six-tenths of an inch in diameter seen at the distance\nof a mile: it would all be hidden by a thread one-twenty-fifth of an\ninch in diameter, held six hundred and fifty feet from the eye. If a\nstraight line could be drawn from a star, Sirius in the east to the\nstar Vega in the west, touching our [Page 71] earth's orbit on one\nside, as T R A (Fig. 28), and a line were to be drawn six months\nlater from the same stars, touching our earth's orbit on the other\nside, as R B T, such a line would not diverge sufficiently from a\nstraight line for us to detect its divergence. Numerous vain\nattempts had been made, up to the year 1835, to detect and measure\nthe angle of parallax by which we could rescue some one or more of\nthe stars from the inconceivable depths of space, and ascertain\ntheir distance from us. We are ever impelled to triumph over what is\ndeclared to be unconquerable. There are peaks in the Alps no man has\never climbed. They are assaulted every year by men zealous of more\nworlds to conquer. So these greater heights of the heavens have been\nassaulted, till some ambitious spirits have outsoared even\nimagination by the certainties of mathematics.\n\n[Illustration: Fig. 28.]\n\nIt is obvious that if one star were three times as far from us as\nanother, the nearer one would seem to be displaced by our movement\nin our orbit three times as much as the other; so, by comparing one\nstar with another, we reach a ground of judgment. The ascertainment\nof longitude at sea by means of the moon affords a good illustration.\nAlong the track where the moon sails, nine bright stars, four planets,\nand the sun have been selected. The nautical almanacs give the\ndistance of the moon from these successive stars every hour in\nthe night for three years in advance. The sailor can measure the\ndistance at any time by his sextant. Looking from the world at\nD (Fig. 29), the distance of the moon and [Page 72] star is A E,\nwhich is given in the almanac. Looking from C, the distance is only\nB E, which enables even the uneducated sailor to find the distance,\nC D, on the earth, or his distance from Greenwich.\n\n[Illustration: Fig. 29.--Mode of Ascertaining Longitude.]\n\nSo, by comparisons of the near and far stars, the approximate distance\nof a few of them has been determined. The nearest one is the brightest\nstar in the Centaur, never visible in our northern latitudes, which\nhas a parallax of about one second. The next nearest is No. 61 in\nthe Swan, or 61 Cygni, having a parallax of 0\".34. Approximate\nmeasurements have been made on Sirius, Capella, the Pole Star,\netc., about eighteen in all. The distances are immense: only the\nswiftest agents can traverse them. If our earth were suddenly to\ndissolve its allegiance to the king of day, and attempt a flight\nto the North Star, and should maintain its flight of one thousand\nmiles a minute, it would flyaway toward Polaris for thousands upon\nthousands of years, till a million years had passed away, before\nit reached that northern dome of the distant sky, and gave its\nnew allegiance to another sun. The sun it had left behind it would\ngradually diminish till it was small as Arcturus, then small as\ncould be discerned by the naked eye, until at last it would finally\nfade out in utter darkness long before the new sun was reached.\nLight can traverse the distance around our earth eight times in\none second. It comes in eight minutes from the sun, but it takes\nthree and a quarter years to come from Alpha [Page 73] Centauri,\nseven and a quarter years from 61 Cygni, and forty-five years from\nthe Polar Star.\n\nSometimes it happens that men steer along a lee shore, dependent\nfor direction on Polaris, that light-house in the sky. Sometimes it\nhas happened that men have traversed great swamps by night when that\nstar was the light-housse of freedom. In either case the exigency\nof life and liberty was provided for forty-five years before by a\nProvidence that is divine.\n\nWe do not attempt to name in miles these enormous distances; we\nmust seek another yard-stick. Our astronomical unit and standard of\nmeasurement is the distance of the earth from the sun--92,500,000\nmiles. This is the golden reed with which we measure the celestial\ncity. Thus, by laying down our astronomical unit 226,000 times, we\nmeasure to Alpha Centauri, more than twenty millions of millions\nof miles. Doubtless other suns are as far from Alpha Centauri and\neach other as that is from ours.\n\nStars are not near or far according to their brightness. 61 Cygni is\na telescopic star, while Sirius, the brightest star in the heavens,\nis twice as far away from us. One star differs from another star\nin intrinsic glory.\n\nThe highest testimonies to the accuracy of these celestial observations\nare found in the perfect predictions of eclipses, transits of planets\nover the sun, occultation of stars by the moon, and those statements\nof the Nautical Almanac that enable the sailor to know exactly\nwhere he is on the pathless ocean by the telling of the stars:\n\"On the trackless ocean this book is the mariner's trusted friend\nand counsellor; daily and nightly its revelations bring safety\nto ships in all parts of the [Page 74] world. It is something more\nthan a mere book; it is an ever-present manifestation of the order\nand harmony of the universe.\"\n\nAnother example of this wonderful accuracy is found in tracing\nthe asteroids. Within 200,000,000 or 300,000,000 miles from the\nsun, the one hundred and ninety-two minute bodies that have been\nalready discovered move in paths very nearly the same--indeed two of\nthem traverse the same orbit, being one hundred and eighty degrees\napart;--they look alike, yet the eye of man in a few observations\nso determines the curve of each orbit, that one is never mistaken\nfor another. But astronomy has higher uses than fixing time,\nestablishing landmarks, and guiding the sailor. It greatly quickens\nand enlarges thought, excites a desire to know, leads to the utmost\nexactness, and ministers to adoration and love of the Maker of\nthe innumerable suns.\n\n\n\n\n[Page 75]\nV.\n\nTHE SUN.\n\n\"And God made two great lights; the greater light to rule the day, and\nthe lesser light to rule the night: he made the stars also.\"--_Gen._\ni. 16.\n\n[Page 76]\n\"It is perceived that the sun of the world, with all its essence,\nwhich is heat and light, flows into every tree, and into every\nshrub and flower, and into every stone, mean as well as precious;\nand that every object takes its portion from this common influx,\nand that the sun does not divide its light and heat, and dispense\na part to this and a part to that. It is similar with the sun of\nheaven, from which the Divine love proceeds as heat, and the Divine\nwisdom as light; these two flow into human minds, as the heat and\nlight of the sun of the world into bodies, and vivify them according\nto the quality of the minds, each of which takes from the common\ninflux as much as is necessary.\"--SWEDENBORG.\n\n\n\n\n[Page 77]\nV.\n\n_THE SUN._\n\nSuppose we had stood on the dome of Boston Statehouse November 9th,\n1872, on the night of the great conflagration, and seen the fire\nbreak out; seen the engines dash through the streets, tracking their\npath by their sparks; seen the fire encompass a whole block, leap\nthe streets on every side, surge like the billows of a storm-swept\nsea; seen great masses of inflammable gas rise like dark clouds\nfrom an explosion, then take fire in the air, and, cut off from\nthe fire below, float like argosies of flame in space. Suppose we\nhad felt the wind that came surging from all points of the compass\nto fan that conflagration till it was light enough a mile away to\nsee to read the finest print, hot enough to decompose the torrents\nof water that were dashed on it, making new fuel to feed the flame.\nSuppose we had seen this spreading fire seize on the whole city,\nextend to its environs, and, feeding itself on the very soil, lick\nup Worcester with its tongues of flame--Albany, New York, Chicago,\nSt. Louis, Cincinnati--and crossing the plains swifter than a prairie\nfire, making each peak of the Rocky Mountains hold up aloft a separate\ntorch of flame, and the Sierras whiter with heat than they ever were\nwith snow, the waters of the Pacific resolve into their constituent\nelements of oxygen and hydrogen, and [Page 78] burn with\nunquenchable fire! We withdraw into the air, and see below a world\non fire. All the prisoned powers have burst into intensest activity.\nQuiet breezes have become furious tempests. Look around this flaming\nglobe--on fire above, below, around--there is nothing but fire. Let\nit roll beneath us till Boston comes round again. No ember has yet\ncooled, no spire of flame has shortened, no surging cloud has been\nquieted. Not only are the mountains still in flame, but other ranges\nburst up out of the seething sea. There is no place of rest, no\nplace not tossing with raging flame! Yet all this is only a feeble\nfigure of the great burning sun. It is but the merest hint, a\nmillion times too insignificant.\n\nThe sun appears small and quiet to us because we are so far away.\nSeen from the various planets, the relative size of the sun appears\nas in Fig. 30. Looked for from some of the stars about us, the\nsun could not be seen at all. Indeed, seen from the earth, it is\nnot always the same size, because the distance is not always the\nsame. If we represent the size of the sun by one thousand on the\n23d of September or 21st of March, it would be represented by nine\nhundred and sixty-seven on the 1st of July, and by one thousand\nand thirty-four on the 1st of January.\n\n[Illustration: Fig. 30.--Relative Size of Sun as seen from Different\nPlanets.]\n\nWe sometimes speak of the sun as having a diameter of 860,000 miles.\nWe mean that that is the extent of the body as soon by the eye.\nBut that is a small part of its real diameter. So we say the earth\nhas an equatorial diameter of 7925-1/2 miles, and a polar one of\n7899. But the air is as much a part of the earth as the rocks are.\nThe electric currents are as much a part of the [Page 79] earth as\nthe ores and mountains they traverse. What the diameter of the earth\nis, including these, no man can tell. We used to say the air\nextended forty-five miles, but we now know that it reaches vastly\nfarther. So of the sun, we might almost say that its diameter is\ninfinite, for its light and heat reach beyond our measurement. Its\nliving, throbbing heart sends out pulsations, keeping all space full\nof its tides of living light.\n\n[Page 80]\n[Illustration: Fig. 31.--Zodiacal Light.]\n\nWe might say with evident truth that the far-off planets are a\npart of the sun, since the space they traverse is filled with the\npower of that controlling king; not only with light, but also with\ngravitating power.\n\nBut come to more ponderable matters. If we look [Page 81] into our\nwestern sky soon after sunset, on a clear, moonless night in March\nor April, we shall see a dim, soft light, somewhat like the\nmilky-way, often reaching, well defined, to the Pleiades. It is\nwedge-shaped, inclined to the south, and the smallest star can\neasily be seen through it. Mairan and Cassini affirm that they have\nseen sudden sparkles and movements of light in it. All our best\ntests show the spectrum of this light to be continuous, and\ntherefore reflected; which indicates that it is a ring of small\nmasses of meteoric matter surrounding the sun, revolving with it and\nreflecting its light. One bit of stone as large as the end of one's\nthumb, in a cubic mile, would be enough to reflect what light we see\nlooking through millions of miles of it. Perhaps an eye sufficiently\nkeen and far away would see the sun surrounded by a luminous disk,\nas Saturn is with his rings. As it extends beyond the earth's orbit,\nif this be measured as a part of the sun, its diameter would be\nabout 200,000,000 miles.\n\nCome closer. When the sun is covered by the disk of the moon at\nthe instant of total eclipse, observers are startled by strange\nswaying luminous banners, ghostly and weird, shooting in changeful\nplay about the central darkness (Fig. 32). These form the corona.\nMen have usually been too much moved to describe them, and have\nalways been incapable of drawing them in the short minute or two\nof their continuance. But in 1878 men travelled eight thousand\nmiles, coming and returning, in order that they might note the\nthree minutes of total eclipse in Colorado. Each man had his work\nassigned to him, and he was drilled to attend to that and nothing\nelse. Improved instruments were put into his [Page 82] hands, so\nthat the sun was made to do his own drawing and give his own picture\nat consecutive instants. Fig. 33 is a copy of a photograph of the\ncorona of 1878, by Mr. Henry Draper. It showed much less\nchangeability that year than common, it being very near the time of\nleast sun-spot. The previous picture was taken near the time of\nmaximum sun-spot.\n\n[Illustration: Fig. 32.--The Corona in 1858, Brazil.]\n\nIt was then settled that the corona consists of reflected light,\nsent to us from dust particles or meteoroids swirling in the vast\nseas, giving new densities and [Page 83] rarities, and hence this\nchangeful light. Whether they are there by constant projection, and\nfall again to the sun, or are held by electric influence, or by\nforce of orbital revolution, we do not know. That the corona cannot\nbe in any sense an atmosphere of any continuous gas, is seen from\nthe fact that the comet of 1843, passing within 93,000 miles of the\nbody of the sun, was not burned out of existence as a comet, nor in\nany perceptible degree retarded in its motion. If the sun's diameter\nis to include the corona, it will be from 1,260,000 to 1,460,000\nmiles.\n\n[Illustration: Fig. 33.--The Corolla in 1878, Colorado.]\n [Page 84] Come closer still. At the instant of the totality of the\n eclipse red flames of most fantastic shape play along the edge of\n the moon's disk. They can be seen at any time by the use of a\n proper telescope with a spectroscope attached. I have seen them\n with great distinctness and brilliancy with the excellent\n eleven-inch telescope of the Wesleyan University. A description of\n their appearance is best given in the language of Professor Young,\n of Princeton College, who has made these flames the object of most\n successful study. On September 7th, 1871, he was observing a large\n hydrogen cloud by the sun's edge. This cloud was about 100,000\n miles long, and its upper side was some 50,000 miles above the\n sun's surface, the lower side some 15,000 miles. The whole had the\n appearance of being supported on pillars of fire, these seeming\n pillars being in reality hydrogen jets brighter and more active\n than the substance of the cloud. At half-past twelve, when\n Professor Young chanced to be called away from his observatory,\n there were no indications of any approaching change, except that\n one of the connecting stems of the southern extremity of the cloud\n had grown considerably brighter and more curiously bent to one\n side; and near the base of another, at the northern end, a little\n brilliant lump had developed itself, shaped much like a summer\n thunderhead.\n\n[Illustration: Fig. 34.--Solar Prominences of Flaming Hydrogen.]\n\nBut when Professor Young returned, about half an hour later, he\nfound that a very wonderful change had taken place, and that a\nvery remarkable process was actually in progress. \"The whole thing\nhad been literally blown to shreds,\" he says, \"by some inconceivable\nuprush from beneath. In place of the quiet cloud I had [Page 87]\nleft, the air--if I may use the expression--was filled with the\nflying _d\u00e9bris_, a mass of detached vertical fusi-form fragments,\neach from ten to thirty seconds (_i. e._, from four thousand five\nhundred to thirteen thousand five hundred miles) long, by two or\nthree seconds (nine hundred to thirteen hundred and fifty miles)\nwide--brighter, and closer together where the pillars had formerly\nstood, and rapidly ascending. When I looked, some of them had\nalready reached a height of nearly four minutes (100,000 miles); and\nwhile I watched them they arose with a motion almost perceptible to\nthe eye, until, in ten minutes, the uppermost were more than 200,000\nmiles above the solar surface. This was ascertained by careful\nmeasurements, the mean of three closely accordant determinations\ngiving 210,000 miles as the extreme altitude attained. I am\nparticular in the statement, because, so far as I know,\nchromatospheric matter (red hydrogen in this case) has never before\nbeen observed at any altitude exceeding five minutes, or 135,000\nmiles. The velocity of ascent, also--one hundred and sixty-seven\nmiles per second--is considerably greater than anything hitherto\nrecorded. * * * As the filaments arose, they gradually faded away\nlike a dissolving cloud, and at a quarter past one only a few filmy\nwisps, with some brighter streamers low down near the\nchromatosphere, remained to mark the place. But in the mean while\nthe little 'thunder-head' before alluded to had grown and developed\nwonderfully into a mass of rolling and ever-changing flame, to speak\naccording to appearances. First, it was crowded down, as it were,\nalong the solar surface; later, it arose almost pyramidally 50,000\nmiles in height; then [Page 88] its summit was drawn down into long\nfilaments and threads, which were most curiously rolled backward and\nforward, like the volutes of an Ionic capital, and finally faded\naway, and by half-past two had vanished like the other. The whole\nphenomenon suggested most forcibly the idea of an explosion under\nthe great prominence, acting mainly upward, but also in all\ndirections outward; and then, after an interval, followed by a\ncorresponding in-rush.\"\n\nNo language can convey nor mind conceive an idea of the fierce\ncommotion we here contemplate. If we call these movements hurricanes,\nwe must remember that what we use as a figure moves but one hundred\nmiles an hour, while these move one hundred miles a second. Such\nstorms of fire on earth, \"coming down upon us from the north, would,\nin thirty seconds after they had crossed the St. Lawrence, be in\nthe Gulf of Mexico, carrying with them the whole surface of the\ncontinent in a mass not simply of ruins but of glowing vapor, in\nwhich the vapors arising from the dissolution of the materials\ncomposing the cities of Boston, New York, and Chicago would be\nmixed in a single indistinguishable cloud.\" In the presence of\nthese evident visions of an actual body in furious flame, we need\nhesitate no longer in accepting as true the words of St. Peter\nof the time \"in which the [atmospheric] heavens shall pass away\nwith a great noise, and the elements shall melt with fervent heat;\nthe earth also, and the works that are therein, shall be burned\nup.\"\n\nThis region of discontinuous flame below the corona is called the\nchromosphere. Hydrogen is the principal material of its upper part;\niron, magnesium, and other [Page 89] metals, some of them as yet\nunknown on earth, but having a record in the spectrum, in the denser\nparts below. If these fierce fires are a part of the Sun, as they\nassuredly are, its diameter would be from 1,060,000 to 1,260,000\nmiles.\n\nLet us approach even nearer. We see a clearly recognized even disk,\nof equal dimensions in every direction. This is the photosphere.\nWe here reach some definitely measurable data for estimating its\nvisible size. We already know its distance. Its disk subtends an\nangle of 32' 12\".6, or a little more than half a degree. Three\nhundred and sixty such suns, laid side by side, would span the\ncelestial arch from east to west with a half circle of light. Two\nlines drawn from our earth at the angle mentioned would be 860,000\nmiles apart at the distance of 92,500,000 miles. This, then, is\nthe diameter of the visible and measurable part of the sun. It\nwould require one hundred and eight globes like the earth in a line\nto measure the sun's diameter, and three hundred and thirty-nine,\nto be strung like the beads of a necklace, to encircle his waist.\nThe sun has a volume equal to 1,245,000 earths, but being only\none-quarter as dense, it has a mass of only 326,800 earths. It\nhas seven hundred times the mass of all the planets, asteroids,\nand satellites put together. Thus it is able to control them all\nby its greater power of attraction.\n\nConcerning the condition of the surface of the sun many opinions\nare held. That it is hot beyond all estimate is indubitable. Whether\nsolid or gaseous we are not sure. Opinions differ: some incline to\nthe first theory, others to the second; some deem the sun composed\nof solid particles, floating in gas so condensed [Page 90] by\npressure and attraction as to shine like a solid. It has no sensible\nchanges of general level, but has prodigious activity in spots.\nThese spots have been the objects of earnest and almost hourly study\non the part of such men as Secchi, Lockyer, Faye, Young, and others,\nfor years. But it is a long way off to study an object. No telescope\nbrings it nearer than 200,000 miles. Theory after theory has been\nadvanced, each one satisfactory in some points, none in all. The\nfacts about the spots are these: They are most abundant on the two\nsides of the equator. They are gregarious, depressed below the\nsurface, of vast extent, black in the centre, usually surrounded by\na region of partial darkness, beyond which is excessive light. They\nhave motion of their own over the surface--motion rotating about an\naxis, upward and downward about the edges. They change their\napparent shape as the sun carries them across its disk by axial\nrevolution, being narrow as they present their edges to us, and\nrounder as we look perpendicularly into them (Fig. 35).\n\n[Illustration: Fig. 35.--Change in Spots as rotated across the Disk,\nshowing Cavities.]\n\nThese spots are also very variable in number, sometimes there being\nnone for nearly two hundred days, and again whole years during which\nthe sun is never without them. The period from minimum to maximum\n[Page 91] of spots is about eleven years. We might look for them\nagain and again in vain this year (1878). They will be most numerous\nin 1882 and 1893. The cause of this periodicity was inferred to be\nthe near approach of the enormous planet Jupiter, causing\ndisturbance by its attraction. But the periods do not correspond,\nand the cause is the result of some law of solar action to us as yet\nunknown.\n\nThese spots may be seen with almost any telescope, the eye being\nprotected by deeply colored glasses.\n\nUntil within one hundred years they were supposed to be islands of\nscori\u00e6 floating in the sea of molten matter. But they were depressed\nbelow the surface, and showed a notch when on the edge. Wilson\noriginated and Herschel developed the theory that the sun's real\nbody was dark, cool, and habitable, and that the photosphere was\na luminous stratum at a distance from the real body, with openings\nshowing the dark spots below. Such a sun would have cooled off in\na week, but would previously have annihilated all life below.\n\nThe solar spots being most abundant on the two sides of the equator,\nindicates their cyclonic character; the centre of a cyclone is\nrarefied, and therefore colder, and cold on the sun is darkness.\nM. Faye says: \"Like our cyclones, they are descending, as I have\nproved by a special study of these terrestrial phenomena. They\ncarry down into the depths of the solar mass the cooler materials\nof the upper layers, formed principally of hydrogen, and thus produce\nin their centre a decided extinction of light and heat as long as\nthe gyratory movement continues. Finally, the hydrogen set free\nat the base of the whirlpool becomes reheated at this [Page 92]\ngreat depth, and rises up tumultuously around the whirlpool, forming\nirregular jets, which appear above the chromosphere. These jets\nconstitute the protuberances. The whirlpools of the sun, like those\non the earth, are of all dimensions, from the scarcely visible pores\nto the enormous spots which we see from time to time. They have,\nlike those of the earth, a marked tendency, first to increase and\nthen to break up, and thus form a row of spots extending along the\nsame parallel.\"\n\n[Illustration: Fig. 36.--Solar spot, by Langley.]\n\nA spot of 20,000 miles diameter is quite small; there was one 14,816\nmiles across, visible to the naked eye for a week in 1843. This\nparticular sun-spot somewhat [Page 93] helped the Millerites. On the\nday of the eclipse, in 1858, a spot over 107,000 miles in extent was\nclearly seen. In such vast tempests, if there were ships built as\nlarge as the whole earth, they would be tossed like autumn leaves in\nan ocean storm.\n\nThe revolution of the sun carries a spot across its face in about\nfourteen days. After a lapse of as much more time, they often reappear\non the other side, changed but recognizable. They often break ont\nor disappear under the eye of the observer. They divide like a\npiece of ice dropped on a frozen pond, the pieces sliding off in\nevery direction, or combine like separate floes driven together\ninto a pack. Sometimes a spot will last for more than two hundred\ndays, recognizable through six or eight revolutions. Sometimes\na spot will last only half an hour.\n\nThe velocities indicated by these movements are incredible. An\nup-rush and down-rush at the sides has been measured of twenty\nmiles a second; a side-rush or whirl, of one hundred and twenty\nmiles a second. These tempests rage from a few days to half a year,\ntraversing regions so wide that our Indian Ocean, the realm of\nstorms, is too small to be used for comparison; then, as they cease,\nthe advancing sides of the spots approach each other at the rate of\n20,000 miles an hour; they strike together, and the rising spray\nof fire leaps thousands of miles into space. It falls again into the\nincandescent surge, rolls over mountains as the sea over pebbles, and\nall this for eon after eon without sign of exhaustion or diminution.\nAll these swift succeeding Himalayas of fire, where one hundred\nworlds could be buried, do not usually prevent the sun's appearing\nto our far-off eyes as a perfect sphere.\n\n[Page 94]\n_What the Sun does for us._\n\nTo what end does this enormous power, this central source of power,\nexist? That it could keep all these gigantic forces within itself\ncould not be expected. It is in a system where every atom is made\nto affect every other atom, and every world to influence every\nother. The Author of all lives only to do good, to send rain on\nthe just and unjust, to cause his sun to rise on the evil and the\ngood, and to give his spirit, like a perpetually widening river,\nto every man to profit withal.\n\nThe sun reaches his unrelaxing hand of gravitation to every other\nworld at every instant. The tendency of every world is to fly off\nin a straight line. This tendency must be momentarily curbed, and\nthe planet held in its true curve about the sun. These giant worlds\nmust be perfectly handled. Their speed, amounting to seventy times\nas fast as that of a rifle-ball, must be managed. Each and every\nworld may be said to be lifted momentarily and swung perpetually\nat arm's-length by the power of the sun.\n\nThe sun warms us. It would convey but a small idea of the truth\nto state how many hundreds of millions of cubic miles of ice could\nbe hailed at the sun every second without affecting its heat; but,\nif any one has any curiosity to know, it is 287,200,000 cubic miles\nof ice per second.\n\nWe journey through space which has a temperature of 200\u00b0 below\nzero; but we live, as it were, in a conservatory, in the midst of\nperpetual winter. We are roofed over by the air that treasures the\nheat, floored under by strata both absorptive and retentive of heat,\n[Page 95] and between the earth and air violets grow and grains\nripen. The sun has a strange chemical power. It kisses the cold\nearth, and it blushes with flowers and matures the fruit and grain.\nWe are feeble creatures, and the sun gives us force. By it the light\nwinds move one-eighth of a mile an hour, the storm fifty miles, the\nhurricane one hundred. The force is as the square of the velocity.\nIt is by means of the sun that the merchant's white-sailed ships are\nblown safely home. So the sun carries off the miasma of the marsh,\nthe pollution of cities, and then sends the winds to wash and\ncleanse themselves in the sea-spray. The water-falls of the earth\nturn machinery, and make Lowells and Manchesters possible, because\nthe sun lifted all that water to the hills.\n\nIntermingled with these currents of air are the currents of electric\npower, all derived from the sun. These have shown their swiftness\nand willingness to serve man. The sun's constant force displayed\non the earth is equal to 543,000,000,000 engines of 400-horse power\neach, working day and night; and yet the earth receives only\n1/21500000000 part of the whole force of the sun.\n\nBesides all this, the sun, with provident care, has made and given\nto us coal. This omnipotent worker has stored away in past ages\nan inexhaustible reservoir of his power which man may easily mine\nand direct, thus releasing himself from absorbing toil.\n\nEXPERIMENTS.\n\nAny one may see the spots on the sun who has a spy-glass. Darken\nthe room and put the glass through an opening toward the sun, as\nshown in Fig. 37. The eye-piece should be drawn out about half\nan inch beyond [Page 96] its usual focusing for distant objects. The\nfarther it is drawn, the nearer must we hold the screen for a\nperfect image.\n\nBy holding a paper near the eye-piece, the proper direction of\nthe instrument may be discovered without injury to the eyes. By\nthis means the sun can be studied from day to day, and its spots or\nthe transits of Mercury and Venus shown to any number of spectators.\n\n[Illustration: Fig. 37.--Holding Telescope to see the Sun's Spots.]\n\nFirst covering the eyes with very dark or smoked glasses, erect\na disk of pasteboard four inches in diameter between you and the\nsun; close one eye; stand near it, and the whole sun is obscured.\nWithdraw from it till the sun's rays just shoot over the edge of\nthe disk on every side. Measure the distance from the eye to the\ndisk. You will be able to determine the distance of the sun by\nthe rule of three: thus, as four inches is to 860,000 miles, so\nis distance from eye to disk to distance from disk to the sun.\nTake such measurements at sunrise, noon, and sunset, and see the\napparently differing sizes due to refraction.\n\n\n\n\n[Page 97]\nVI.\n\nTHE PLANETS, AS SEEN FROM SPACE.\n\n\"He hangeth the earth upon nothing.\"--_Job_ xxvi. 7.\n\n[Page 98]\n\"Let a power be delegated to a finite spirit equal to the projection\nof the most ponderous planet in its orbit, and, from an exhaustless\nmagazine, let this spirit select his grand central orb. Let him with\npuissant arm locate it in space, and, obedient to his mandate, there\nlet it remain forever fixed. He proceeds to select his planetary\nglobes, which he is now required to marshal in their appropriate\norder of distance from the sun. Heed well this distribution; for\nshould a single globe be misplaced, the divine harmony is destroyed\nforever. Let us admit that finite intelligence may at length determine\nthe order of combination; the mighty host is arrayed in order.\nThese worlds, like fiery coursers, stand waiting the command to\nfly. But, mighty spirit, heed well the grand step, ponder well\nthe direction in which thou wilt launch each wailing world; weigh\nwell the mighty impulse soon to be given, for out of the myriads\nof directions, and the myriads of impulsive forces, there comes\nbut a single combination that will secure the perpetuity of your\ncomplex scheme. In vain does the bewildered finite spirit attempt\nto fathom this mighty depth. In vain does it seek to resolve the\nstupendous problem. It turns away, and while endued with omnipotent\npower, exclaims, 'Give to me infinite wisdom, or relieve me from\nthe impossible task!'\"-0. M. MITCHEL, LL. D.\n\n\n\n\n[Page 99]\nVI.\n\n_THE PLANETS, AS SEEN FROM SPACE_\n\nIf we were to go out into space a few millions of miles from either\npole of the sun, and were endowed with wonderful keenness of vision,\nwe should perceive certain facts, viz: That space is frightfully\ndark except when we look directly at some luminous body. There is\nno air to bend the light out of its course, no clouds or other\nobjects to reflect it in a thousand directions. Every star is a\nbrilliant point, even in perpetual sunshine. The cold is frightful\nbeyond the endurance of our bodies. There is no sound of voice in\nthe absence of air, and conversation by means of vocal organs being\nimpossible, it must be carried on by means of mind communication.\nWe see below an unrevolving point on the sun that marks its pole.\nRanged round in order are the various planets, each with its axis\npointing in very nearly the same direction. All planets, except\npossibly Venus, and all moons except those of Uranus and Neptune,\npresent their equators to the sun. The direction of orbital and\naxial revolution seen from above the North Pole would be opposite\nto that of the hands of a watch.\n\n[Illustration: Fig. 38.--Orbits and Comparative Sizes of the Planets.]\n\nThe speed of this orbital revolution must be proportioned to the\ndistance from the sun. The attraction of the sun varies inversely\nas the square of the distance. [Page 100] It holds a planet with a\ncertain power; one twice as far off, with one-fourth that power.\nThis attraction must be counterbalanced by centrifugal force; great\nforce from great speed when attraction is great, and small from less\n[Page 101] speed when attractive power is diminished by distance.\nHence Mercury must go 29.5 miles per second--seventy times as fast\nas a rifle-ball that goes two-fifths of a mile in a second--or be\ndrawn into the sun; while Neptune, seventy-five times as far off,\nand hence attracted only 1/5626 as much, must be slowed down to 3.4\nmiles a second to prevent its flying away from the feebler\nattraction of the sun. The orbital velocity of the various planets\nin miles per second is as follows:\n\n  Mercury  29.55  |  Jupiter  8.06\n  Venus    21.61  |  Saturn   5.95\n  Earth    18.38  |  Uranus   4.20\n  Mars     14.99  |  Neptune  3.36\n\nHence, while the earth makes one revolution in its year, Mercury\nhas made over four revolutions, or passed through four years; the\nslower Neptune has made only 1/164 of one revolution.\n\nThe time of axial revolution which determines the length of the\nday varies with different planets. The periods of the four planets\nnearest the sun vary only half an hour from that of the earth,\nwhile the enormous bodies of Jupiter and Saturn revolve in ten\nand ten and a quarter hours respectively. This high rate of speed,\nand its resultant, centrifugal force, has aided in preventing these\nbodies from becoming as dense as they would otherwise be--Jupiter\nbeing only 0.24 as dense as the earth, and Saturn only 0.13. This\nextremely rapid revolution produces a great flattening at the poles.\nIf Jupiter should rotate four times more rapidly than it does, it\ncould not be held together compactly. As it is, the polar diameter\nis five thousand miles less than the equatorial: the difference\nin diameters produced by the [Page 102] same cause on the earth,\nowing to the slower motion and smaller mass, being only twenty-six\nmiles. The effect of this will be more specifically treated\nhereafter.\n\nThe difference in the size of the planets is very noticeable. If\nwe represent the sun by a gilded globe two feet in diameter, we\nmust represent Vulcan and Mercury by mustard-seeds; Venus, by a\npea; Earth, by another; Mars, by one-half the size; Asteroids, by\nthe motes in a sunbeam; Jupiter, by a small-sized orange; Saturn,\nby a smaller one; Uranus, by a cherry; and Neptune, by one a little\nlarger.\n\nApply the principle that attraction is in proportion to the mass,\nand a man who weighs one hundred and fifty pounds on the earth\nweighs three hundred and ninety-six on Jupiter, and only fifty-eight\non Mars; while on the Asteroids he could play with bowlders for\nmarbles, hurl hills like Milton's angels, leap into the fifth-story\nwindows with ease, tumble over precipices without harm, and go\naround the little worlds in seven jumps.\n\n[Illustration: Fig. 39.--Orbit of Earth, showing Parallelism of\nAxis and Seasons.]\n\nThe seasons of a planet are caused by the inclination of its axis\nto the plane of its orbit. In Fig. 39 the rotating earth is seen\nat A, with its northern pole turning in constant sunlight, and\nits southern pole in constant darkness; everywhere south of the\nequator is more darkness than day, and hence winter. Passing on\nto B, the world is seen illuminated equally on each side of the\nequator. Every place has its twelve hours' darkness and light at\neach revolution. But at C--the axis of the earth always preserving\nthe same direction--the northern pole is shrouded in continual\ngloom. Every place [Page 105] north of the equator gets more\ndarkness than light, and hence winter.\n\nThe varying inclination of the axes of the different planets gives\na wonderful variety to their seasons. The sun is always nearly\nover the equator of Jupiter, and every place has nearly its five\nhours day and five hours night. The seasons of Earth, Mars, and\nSaturn are so much alike, except in length, that no comment is\nnecessary. The ice-fields at either pole of Mars are observed to\nenlarge and contract, according as it is winter or summer there.\nSaturn's seasons are each seven and a half years long. The alternate\ndarkness and light at the poles is fifteen years long.\n\nBut the seasons of Venus present the greatest anomaly, if its assigned\ninclination of axis (75\u00b0) can be relied on as correct, which is\ndoubtful. Its tropic zone extends nearly to the pole, and at the\nsame time the winter at the other pole reaches the equator. The\nshort period of this planet causes it to present the south pole to\nthe sun only one hundred and twelve days after it has been scorching\nthe one at the north. This gives two winters, springs, summers, and\nautumns to the equator in two hundred and twenty-five days.\n\nIf each whirling world should leave behind it a trail of light to\nmark its orbit, and our perceptions of form were sufficiently acute,\nwe should see that these curves of light are not exact circles, but\na little flattened into an ellipse, with the sun always in one\nof the foci. Hence each planet is nearer to the sun at one part\nof its orbit than another; that point is called the perihelion,\nand the farthest point aphelion. This eccentricity of orbit, or\ndistance of the sun from the centre, is very small. [Page 106] In\nthe case of Venus it is only .007 of the whole, and in no instance\nis it more than .2, viz., that of Mercury. This makes the sun appear\ntwice as large, bright, and hot as seen and felt on Mercury at its\nperihelion than at its aphelion. The earth is 3,236,000 miles nearer\nto the sun in our winter than summer. Hence the summer in the\nsouthern hemisphere is more intolerable than in the northern. But\nthis eccentricity is steadily diminishing at a uniform rate, by\nreason of the perturbing influence of the other planets. In the case\nof some other planets it is steadily increasing, and, if it were to\ngo on a sufficient time, might cause frightful extremes of\ntemperature; but Lalande has shown that there are limits at which it\nis said, \"Thus far shalt thou go, and no farther.\" Then a\ncompensative diminution will follow.\n\nConceive a large globe, to represent the sun, floating in a round\npond. The axis will be inclined 7-1/2\u00b0 to the surface of the water,\none side of the equator be 7-1/2\u00b0 below the surface, and the other\nside the same distance above. Let the half-submerged earth sail\naround the sun in an appropriate orbit. The surface of the water\nwill be the plane of the orbit, and the water that reaches out\nto the shore, where the stars would be set, will be the plane of\nthe ecliptic. It is the plane of the earth's orbit extended to\nthe stars.\n\nThe orbits of all the planets do not lie in the same plane, but\nare differently inclined to the plane of the ecliptic, or the plane\nof the earth's orbit. Going out from the sun's equator, so as to\nsee all the orbits of the planets on the edge, we should see them\ninclined to that of the earth, as in Fig. 40.\n\n[Illustration: Fig. 40.--Inclination of the Planes of Orbits.]\n\nIf the earth, and Saturn, and Pallas were lying in [Page 107] the\nsame direction from the sun, and the outer bodies were to start in a\ndirect line for the sun, they would not collide with the earth on\ntheir way; but Saturn would pass 4,000,000 and Pallas 50,000,000\nmiles over our heads. From this same cause we do not see Venus and\nMercury make a transit across the disk of the sun at every\nrevolution.\n\n[Illustration: Fig. 41.--Inclination of Orbits of Venus and Earth.\nNodal Line, D B.]\n\nFig. 41 shows a view of the orbits of the earth and Venus seen\nnot from the edge but from a position somewhat above. The point E,\nwhere Venus crosses the plane of the earth's orbit, is called the\nascending node. If the earth were at B when Venus is at E, Venus\nwould be seen on the disk of the sun, making a transit. The same\nwould be true if the earth were at D, and Venus at the descending\nnode F.\n\nThis general view of the flying spheres is full of interest. [Page\n108] While quivering themselves with thunderous noises, all is\nsilent about them; earthquakes may be struggling on their surfaces,\nbut there is no hint of contention in the quiet of space. They are\ntoo distant from one another to exchange signals, except, perhaps,\nthe fleet of asteroids that sail the azure between Mars and Jupiter.\nSome of these come near together, continuing to fill each other's\nsky for days with brightness, then one gradually draws ahead. They\nhave all phases for each other--crescent, half, full, and gibbous.\nThese hundreds of bodies fill the realm where they are with\ninexhaustible variety. Beyond are vast spaces--cold, dark, void of\nmatter, but full of power. Occasionally a little spark of light\nlooms up rapidly into a world so huge that a thousand of our earths\ncould not occupy its vast bulk. It swings its four or eight moons\nwith perfect skill and infinite strength; but they go by and leave\nthe silence unbroken, the darkness unlighted for years.\nNevertheless, every part of space is full of power. Nowhere in its\nwide orbit can a world find a place; at no time in its eons of\nflight can it find an instant when the sun does not hold it in\nsafety and life.\n\n_The Outlook from the Earth._\n\nIf we come in from our wanderings in space and take an outlook from\nthe earth, we shall observe certain movements, easily interpreted\nnow that we know the system, but nearly inexplicable to men who\nnaturally supposed that the earth was the largest, most stable,\nand central body in the universe.\n\nWe see, first of all, sun, moon, and stars rise in the east, mount\nthe heavens, and set in the west. As I [Page 109] revolve in my\npivoted study-chair, and see all sides of the room--library, maps,\nphotographs, telescope, and windows--I have no suspicion that it is\nthe room that whirls; but looking out of a car-window in a depot at\nanother car, one cannot tell which is moving, whether it be his car\nor the other. In regard to the world, we have come to feel its\nwhirl. We have noticed the pyramids of Egypt lifted to hide the sun;\nthe mountains of Hymettus hurled down, so as to disclose the moon\nthat was behind them to the watchers on the Acropolis; and the\nmighty mountains of Moab removed to reveal the stars of the east.\nTrain the telescope on any star; it must be moved frequently, or the\nworld will roll the instrument away from the object. Suspend a\ncannon-ball by a fine wire at the equator; set it vibrating north\nand south, and it swings all day in precisely the same direction.\nBut suspend it directly over the north pole, and set it swinging\ntoward Washington; in six hours after it is swinging toward Rome, in\nItaly; in twelve hours, toward Siam, in Asia; in nineteen hours,\ntoward the Sandwich Islands; and in twenty-four, toward Washington\nagain, not because it has changed the plane of its vibration, but\nbecause the earth has whirled beneath it, and the torsion of the\nwire has not been sufficient to compel the plane of the original\ndirection to change with the turning of the earth. The law of\ninertia keeps it moving in the same direction. The same experimental\nproof of revolution is shown in a proportional degree at any point\nbetween the pole and the equator.\n\nBut the watchers on the Acropolis do not get turned over so as to\nsee the moon at the same time every night. [Page 110] We turn down\nour eastern horizon, but we do not find fair Luna at the same moment\nwe did the night before. We are obliged to roll on for some thirty\nto fifty minutes longer before we find the moon. It must be going in\nthe same direction, and it takes us longer to get round to it than\nif if it were always in the same spot; so we notice a star near the\nmoon one night--it is 13\u00b0 west of the moon the next night. The moon\nis going around the earth from west to east, and if it goes 13\u00b0 in\none day, it will take a little more than twenty-seven days to go the\nentire circle of 360\u00b0.\n\n[Illustration: Fig. 42.--Showing the Sun's Movement among the Stars.]\n\n[Page 111]\nIn our outlook we soon observe that we do not by our revolution\ncome to see the same stars rise at the same hour every night. Orion\nand the Pleiades, our familiar friends in the winter heavens, are\ngone from the summer sky. Have they fled, or are we turned from\nthem? This is easily understood from Fig. 42.\n\nWhen the observer on the earth at A looks into the midnight sky\nhe sees the stars at E; but as the earth passes on to B, he sees\nthose stars at E three minutes sooner every night; and at midnight\nthe stars at F are over his head. Thus in a year, by going around\nthe sun, we have every star of the celestial dome in our midnight\nsky. We see also how the sun appears among the successive\nconstellations. When we are at A, we see the sun among the stars\nat G; but as we move toward B, the sun appears to move toward H.\nIf we had observed the sun rise on the 20th of August, 1876, we\nshould have seen it rise a little before Regulus, and a little\nsouth of it, in such a relation as circle 1 is to the star in Fig.\n43. By sunset the earth had moved enough to make the sun appear\nto be at circle 2, and by the next morning at circle 3, at which\ntime Regulus would rise before the sun. Thus the earth's motion\nseems to make the sun traverse a regular circle among the stars\nonce a year: but it is not the sun that moves.\n\n[Illustration: Fig. 43.]\n\nThere are certain stars that have such irregular, uncertain, vagarious\nways that they were called vagabonds, or planets, by the early\nastronomers. Here is the path of Jupiter in the year 1866 (Fig.\n44). These bodies go forward for awhile, then stop, start aside,\nthen retrograde, [Page 112] and go on again. Some are never seen far\nfrom the sun, and others in all parts of the ecliptic.\n\n[Illustration: Fig. 44.]\n\nFirst see them as they stand to-day, as in Fig. 45. The observer\nstands on the earth at A. It has rolled over so far that he cannot\nsee the sun; it has set. But Venus is still in sight; Jupiter is\n45\u00b0 behind Venus, and Saturn is seen 90\u00b0 farther east. When A has\nrolled a little farther, if he is awake, he will see Mars before\nhe sees the sun; or, in common language, Venus will set after,\nand Mars rise before the sun. All these bodies at near and far\ndistances seem set in the starry dome, as the different stars seem\nin Fig. 42, p. 110.\n\n[Illustration: Fig. 45. Showing Position of Planets.]\n\nThe mysterious movements of advance and retreat are rendered\nintelligible by Fig. 46. The planet Mercury is at A, and, seen from\nthe earth, B is located at _a_, [Page 113] on the background of the\nstars it seems to be among. It remains apparently stationary at _a_\nfor some time, because approaching the earth in nearly a straight\nline. Passing D to C, it appears to retrograde among the stars to\n_c_; remains apparently stationary for some time, then, in passing\nfrom C to E and A, appears to pass back among the stars to _a_. The\nprogress of the earth, meanwhile, although it greatly retards the\napparent motion from A to C, greatly hastens it from C to A.\n\n[Illustration: Fig. 46.--Apparent Movements of an Inferior Planet.]\n\nIt is also apparent that Mercury and Venus, seen from the earth,\ncan never appear far from the sun. They must be just behind the\nsun as evening stars, or just before it as heralds of the morning.\nVenus is never more than 47\u00b0 from the sun, and Mercury never more\nthan 30\u00b0; indeed, it keeps so near the sun that very few people\nhave ever seen the brilliant sparkler. Observe how much larger the\nplanet appears near the earth in conjunction at D than in opposition\nat E. Observe also what phases it must present, and how transits\nsometimes take place.\n\n[Page 114]\nThe movement of a superior planet, one whose orbit is exterior\nto the earth, is clear from Fig. 47. When the earth is at A and\nMars at B, it will appear among the stars at C. When the earth is\nat D, Mars having moved more slowly to E, will have retrograded\nto F. It remains there while the earth passes on, in a line nearly\nstraight, from Mars to G; then, as the earth begins to curve around\nthe sun, Mars will appear to retraverse the distance from F to\nC, and beyond. The farther the superior planet is from the earth\nthe less will be the retrograde movement.\n\n[Illustration: Fig. 47.--Illustrating Movements of a Superior Planet.]\n\nThe reader should draw the orbits in proportion, and, remembering\nthe relative speed of each planet, note the movement of each in\ndifferent parts of their orbits.\n\nTo account for these most simple movements, the earlier astronomers\ninvented the most complex and impossible machinery. They thought the\nearth the centre, and that the sun, moon, and stars were carried\nabout it, as stoves around a person to warm him. They thought these\nstrange movements of the planets were accomplished by mounting them\non subsidiary eccentric wheels in the revolving crystal sphere.\nAll that was [Page 115] needed to give them a right conception was a\nsinking of their world and themselves to an appropriate proportion,\nand an enlargement of their vision, to take in from an exalted\nstand-point a view of the simplicity of the perfect plan.\n\nEXPERIMENTS.\n\nFix a rod, or tube, or telescope pointing at a star in the cast\nor west, and the earth's revolution will be apparent in a moment,\nturning the tube away from the star. Point it at stars about the\nnorth pole, and those on one side will be found going in an opposite\ndirection from those on the other, and very much slower than those\nabout the equator. Anyone can try the pendulum experiment who has\naccess to some lofty place from which to suspend the ball. It was\ntried in Bunker Hill Monument a few years ago, and is to be tried\nin Paris, in the summer of 1879, with a seven-hundred-pound pendulum\nand a suspending wire seventy yards long. The advance and retrograde\nmovements of planets can be illustrated by two persons walking\naround a centre and noticing the place where the person appears\nprojected on the wall beyond.\n\n       *       *       *       *       *\n\n  PROCESSION OF STARS AND SOULS.\n\n  \"I stood upon the open casement,\n     And looked upon the night,\n   And saw the westward-going stars\n     Pass slowly out of sight.\n\n  \"Slowly the bright procession\n     Went down the gleaming arch,\n   And my soul discerned the music\n     Of the long triumphal march;\n\n  \"Till the great celestial army,\n     Stretching far beyond the poles,\n   Became the eternal symbol\n     Of the mighty march of souls.\n\n[Page 116]\n  \"Onward, forever onward,\n     Red Mars led on his clan;\n   And the moon, like a mail\u00e8d maiden,\n     Was riding in the van.\n\n  \"And some were bright in beauty,\n     And some were faint and small,\n   But these might be, in their great heights,\n     The noblest of them all.\n\n  \"Downward, forever downward,\n     Behind earth's dusky shore,\n   They passed into the unknown night--\n     They passed, and were no more.\n\n  \"No more! Oh, say not so!\n     And downward is not just;\n   For the sight is weak and the sense is dim\n     That looks through heated dust.\n\n  \"The stars and the mail\u00e8d moon,\n     Though they seem to fall and die,\n   Still sweep in their embattled lines\n     An endless reach of sky.\n\n  \"And though the hills of Death\n     May hide the bright array,\n   The marshalled brotherhood of souls\n     Still keeps its onward way.\n\n  \"Upward, forever upward,\n     I see their march sublime,\n   And hear the glorious music\n     Of the conquerors of Time.\n\n  \"And long let me remember\n     That the palest fainting one\n   May to diviner vision be\n     A bright and blazing sun.\"\n\n                           THOMAS BUCHANAN READ.\n\n\n\n\n[Page 117]\nVII.\n\nSHOOTING-STARS, METEORS, AND COMETS.\n\n\"The Lord cast down great stones from heaven upon them unto Azekah,\nand they died.\"--_Joshua_ x. II.\n\n[Page 118]\n[Illustration: A SWARM OF METEORS MEETING THE EARTH.\n\nTheir orbits are all parallel. Those coming in direct line to the\neye appear as stars, having no motion. Those on one side of this\nline are seen in foreshortened perspective. Those furthest from\nthe centre, other things being equal, appear longest. The centre,\ncalled the radiant point, of these November meteors is situated\nin Leo; that of the August meteors in Perseus. Over fifty such\nradiant points have been discovered. Over 30,000 meteors have been\nvisible in an hour.]\n\n\n\n\n[Page 119]\nVII.\n\n_SHOOTING-STARS, METEORS, AND COMETS._\n\nBefore particularly considering the larger aggregations of matter\ncalled planets or worlds as individuals, it is best to investigate\na part of the solar system consisting of smaller collections of\nmatter scattered everywhere through space. They are of various\ndensities, from a cloudlet of rarest gas to solid rock; of various\nsizes, from a grain's weight to little worlds; of various relations\nto each other, from independent individuality to related streams\nmillions of miles long. When they become visible they are called\nshooting-stars, which are evanescent star-points darting through\nthe upper air, leaving for an instant a brilliant train; meteors,\nsudden lights, having a discernible diameter, passing over a large\nextent of country, often exploding with violence (Fig. 48), and\nthrowing down upon the earth aerolites; and comets, vast extents\nof ghostly light, that come we know not whence and go we know not\nwhither. All these forms of matter are governed by the same laws\nas the worlds, and are an integral part of the solar system--a\npart of the unity of the universe.\n\n[Illustration: Fig. 48.--Explosion of a Bolide.]\n\nEveryone has seen the so-called shooting-stars. They break out\nwith a sudden brilliancy, shoot a few degrees with quiet speed,\nand are gone before we can say, \"See there!\" The cause of their\nappearance, the [Page 120] conversion of force into heat by their\ncontact with our atmosphere, has been already explained. Other facts\nremain to be studied. They are found to appear about seventy-three\nmiles above the earth, and to disappear about twenty miles nearer\nthe surface. Their average velocity, thirty-five, sometimes rises to\none hundred miles a second. They exhibit different colors, according\nto their different chemical substances, which are consumed. The\nnumber of them to be seen on different nights is exceedingly\nvariable; sometimes not more [Page 121] than five or six an hour,\nand sometimes so many that a man cannot count those appearing in a\nsmall section of sky. This variability is found to be periodic.\nThere are everywhere in space little meteoric masses of matter, from\nthe weight of a grain to a ton, and from the density of gas to rock.\nThe earth meets 7,500,000 little bodies every day--there is\ncollision--the little meteoroid gives out its lightning sign of\nextinction, and, consumed in fervent heat, drops to the earth as gas\nor dust. If we add the number light enough to be seen by a\ntelescope, they cannot be less than 400,000,000 a day. Everywhere we\ngo, in a space as large as that occupied by the earth and its\natmosphere, there must be at least 13,000 bodies--one in 20,000,000\ncubic miles--large enough to make a light visible to the naked eye,\nand forty times that number capable of revealing themselves to\ntelescopic vision. Professor Peirce is about to publish, as the\nstartling result of his investigations, \"that the heat which the\nearth receives directly from meteors is the same in amount which it\nreceives from the sun by radiation, and that the sun receives\nfive-sixths of its heat from the meteors that fall upon it.\"\n\n[Illustration: Fig. 49.--Bolides.]\n\n[Page 121]\nIn 1783 Dr. Schmidt was fortunate enough to have a telescopic view\nof a system of bodies which had turned into meteors. These were two\nlarger bodies followed by several smaller ones, going in parallel\nlines till they were extinguished. They probably had been revolving\nabout each other as worlds and satellites before entering our\natmosphere. It is more than probable that the earth has many such\nbodies, too small to be visible, revolving around it as moons.\n\n[Illustration: Fig. 50.--Santa Rosa Aerolite.]\n\n_Aerolites._\n\nSometimes the bodies are large enough to bear the heat, and the\nunconsumed centre comes to the earth. [Page 123] Their velocity has\nbeen lessened by the resisting air, and the excessive heat\ndiminished. Still, if found soon after their descent, they are too\nhot to be handled. These are called aerolites or air-stones. There\nwas a fall in Iowa, in February, 1875, from which fragments\namounting to five hundred pounds weight were secured. On the evening\nof December 21st, 1876, a meteor of unusual size and brilliancy\npassed over the states of Kansas, Missouri, Illinois, Indiana, and\nOhio. It was first seen in the western part of Kansas, at an\naltitude of about sixty miles. In crossing the State of Missouri it\nbegan to explode, and this breaking up continued while passing\nIllinois, Indiana, and Ohio, till it consisted of a large flock of\nbrilliant balls chasing each other across the sky, the number being\nvariously estimated at from twenty to one hundred. It was\naccompanied by terrific explosions, and was seen along a path of not\nless than a thousand miles. When first seen in Kansas, it is said to\nhave appeared as large as the full moon, and with a train from\ntwenty-five to one hundred feet long. Another, very similar in\nappearance and behavior, passed over a part of the same course in\nFebruary, 1879. At Laigle, France, on April 26th, 1803, about one\no'clock in the day, from two to three thousand fell. The largest did\nnot exceed seventeen pounds weight. One fell in Weston, Connecticut,\nin 1807, weighing two hundred pounds. A very destructive shower is\nmentioned in the book of Joshua, chap. x. ver. 11.\n\nThese bodies are not evenly distributed through space. In some\nplaces they are gathered into systems which circle round the sun\nin orbits as certain as those of the [Page 124] planets. The chain\nof asteroids is an illustration of meteoric bodies on a large scale.\nThey are hundreds in number--meteors are millions. They have their\nregion of travel, and the sun holds them and the giant Jupiter by\nthe same power. The Power that cares for a world cares for a\nsparrow. If their orbit so lies that a planet passes through it, and\nthe planet and the meteors are at the point of intersection at the\nsame time, there must be collisions, and the lightning signs of\nextinction proportioned to the number of little bodies in a given\nspace.\n\nIt is demonstrated that the earth encounters more than one hundred\nsuch systems of meteoric bodies in a single year. It passes through\none on the 10th of August, another on the 11th of November. In\na certain part of the first there is an agglomeration of bodies\nsufficient to become visible as it approaches the sun, and this is\nknown as the comet of 1862; in the second is a similar agglomeration,\nknown as Temple's comet. It is repeating the same thing to say that\nmeteoroids follow in the train of the comets. The probable orbit\nof the November meteors and the comet of 1866 is an exceedingly\nelongated ellipse, embracing the orbit of the earth at one end and\na portion of the orbit of Uranus at the other (Fig. 51). That of\nthe August meteors and the comet of 1862 embraces the orbit of\nthe earth at one end, and thirty per cent. of the other end is\nbeyond the orbit of Neptune.\n\n[Illustration: Fig. 51.--Orbit of the November Meteors and the Comet\nor 1866.]\n\nIn January, 1846, Biela's comet was observed to be divided. At\nits next return, in 1852, the parts were 1,500,000 miles apart.\nThey could not be found on their periodic returns in 1859, 1865,\nand 1872; but it [Page 125] should have crossed the earth's orbit\nearly in September, 1872. The earth itself would arrive at the point\nof crossing two or three months later. If the law of revolution\nheld, we might still expect to find some of the trailing meteoroids\nof the comet not gone by on our arrival. It was shown that the point\nof the earth that would strike them would be toward a certain place\nin the constellation of Andromeda, if the remains of the diluted\ncomet were still there. The prediction was verified in every\nrespect. At the appointed time, place, [Page 126] and direction, the\nstreaming lights were in our sky. That these little bodies belonged\nto the original comet none can doubt. By the perturbations of\nplanetary attraction, or by different original velocities, a comet\nmay be lengthened into an invisible stream, or an invisible stream\nagglomerated till it is visible as a comet.\n\n_Comets._\n\nComets will be most easily understood by the foregoing considerations.\nThey are often treated as if they were no part of the solar system;\nbut they are under the control of the same laws, and owe their\nexistence, motion, and continuance to the same causes as Jupiter and\nthe rest of the planets. They are really planets of wider wandering,\ngreater ellipticity, and less density. They have periodic times\nless than the earth, and fifty times as great as Neptune. They\nare little clouds of gas or meteoric matter, or both, darting into\nthe solar system from every side, at every angle with the plane\nof the ecliptic, becoming luminous with reflected light, passing\nthe sun, and returning again to outer darkness. Sometimes they\nhave no tail, having a nucleus surrounded by nebulosity like a\ndim sun with zodiacal light; sometimes one tail, sometimes half a\ndozen. These follow the comet to perihelion, and precede it afterward\n(Fig. 52). The orbits of some comets are enormously elongated; one\nend may lie inside the earth's orbit, and the other end be as far\nbeyond Neptune as that is from the sun. Of course only a small\npart of such a curve can be studied by us: the comet is visible\nonly when near the sun. The same curve around the sun may be an\norbit that will bring it back again, [Page 127] or one that will\ncarry it off into infinite space, never to return. One rate of speed\non the curve indicates an elliptical orbit that returns; a greater\nrate of speed indicates that it will take a parabolic orbit, which\nnever returns. The exact rate of speed is exceedingly difficult to\ndetermine; hence it cannot be confidently asserted that any comet\never visible will not return. They may all belong to the solar\nsystem; but some will certainly be gone thousands of years before\ntheir fiery forms will greet the watchful eyes of dwellers on the\nearth. A comet that has an elliptic orbit may have it changed to\n[Page 128] parabolic by the accelerations of its speed, by\nattracting planets; or a parabolic comet may become elliptic, and so\npermanently attracted to the system by the retardations of\nattracting bodies. A comet of long period may be changed to one of\nshort period by such attraction, or _vice versa_.\n\n[Illustration: Fig. 52.--Aspects of Remarkable Comets.]\n\nThe number of comets, like that of meteor streams, is exceedingly\nlarge. Five hundred have been visible to the naked eye since the\nChristian era. Two hundred have been seen by telescopes invented\nsince their invention. Some authorities estimate the number belonging\nto our solar system by millions; Professor Peirce says more than\nfive thousand millions.\n\n_Famous Comets._\n\nThe comet of 1680 is perhaps the one that appeared in A.D. 44, soon\nafter the death of Julius C\u00e6sar, also in the reign of Justinian,\nA.D. 531, and in 1106. This is not determined by any recognizable\nresemblance. It had a tail 70\u00b0 long; it was not all arisen when\nits head reached the meridian. It is possible, from the shape of\nits orbit, that it has a periodic time of nine thousand years, or\nthat it may have a parabolic orbit, and never return. Observations\ntaken two hundred years ago have not the exactness necessary to\ndetermine so delicate a point.\n\nOn August 19th, 1682, Halley discovered a comet which he soon declared\nto be one seen by Kepler in 1607. Looking back still farther, he\nfound that a comet was seen in 1531 having the same orbit. Still\nfarther, by the same exact period of seventy-five years, he found\nthat it was the same comet that had disturbed [Page 129] the\nequanimity of Pope Calixtus in 1456. Calculations were undertaken as\nto the result of all the accelerations and retardations by the\nattractions of all the planets for the next seventy-five years.\nThere was not time to finish all the work; but a retardation of six\nhundred and eighteen days was determined, with a possible error of\nthirty days. The comet actually came to time within thirty-three\ndays, on March 12th, 1759. Again its return was calculated with more\nlaborious care. It came to time and passed the sun within three days\nof the predicted time, on the 16th of November, 1835. It passed from\nsight of the most powerful telescopes the following May, and has\nnever since been seen by human eye. But the eye of science sees it\nas having passed its aphelion beyond the orbit of Neptune in 1873,\nand is already hastening back to the warmth and light of the sun. It\nwill be looked for in 1911; and there is good hope of predicting,\nlong before it is seen, the time of its perihelion within a day.\n\n_Biela's lost Comet._--This was a comet with a periodic time of\nsix years and eight months. It was observed in January, 1846, to\nhave separated into two parts of unequal brightness. The lesser\npart grew for a month until it equalled the other, then became\nsmaller and disappeared, while the other was visible a month longer.\nAt disappearance the parts were 200,000 miles asunder. On its next\nreturn, in 1852, the parts were 1,500,000 miles apart; sometimes\none was brighter and sometimes the other; which was the fragment\nand which was the main body could not be recognized. They vanished\nin September, 1852, and have never been seen since. Three revolutions\nhave been made since that time, but no [Page 130] trace of it could\nbe discovered. Probably the same influence that separated it into\nparts, separated the particles till too thin and tenuous to be seen.\nThere is ground for believing that the earth passed through a part\nof it, as before stated under the head of meteors.\n\n_The Great Comet of_ 1843 passed nearer the sun than any known\nbody. It almost grazed the sun. If it ever returns, it will be in\nA.D. 2373.\n\n_Donati's Comet of_ 1858.--This was one of the most magnificent\nof modern times. During the first three months it showed no tail,\nbut from August to October it had developed one forty degrees in\nlength. Its period is about two thousand years. Every reader remembers\nthe comet of the summer of 1875.\n\n_Encke's Comet._--This comet has become famous for its supposed\nconfirmation of the theory that space was filled with a substance\ninfinitely tenuous, which resisted the passage of this gaseous\nbody in an appreciable degree, and in long ages would so retard\nthe motion of all the planets that gravitation would draw them\nall one by one into the sun. We must not be misled by the term\nretardation to suppose it means behind time, for a retarded body\nis before time. If its velocity is diminished, the attraction of\nthe sun causes it to take a smaller orbit, and smaller orbits mean\nincreased speed--hence the supposed retardation would shorten its\nperiodic time. This comet was thought to be retarded two and a\nhalf hours at each revolution. If it was, it would not prove the\nexistence of the resisting medium. Other causes, unknown to us,\nmight account for it. Subsequent and more exact calculations fail\nto find any retardations in at least two revolutions between 1865\nand [Page 131] 1871. Indications point to a retardation of one and a\nhalf hours both before and since. But such discrepancy of result\nproves nothing concerning a resisting medium, but rather is an\nargument against its existence. Besides, Faye's comet, in four\nrevolutions of seven years each, shows no sign of retardation.\n\nThe truth may be this, that a kind of atmosphere exists around the\nsun, perhaps revealed by the zodiacal light, that reaches beyond\nwhere Encke's comet dips inside the orbit of Mercury, and thus\nretards this body, but does not reach beyond the orbit of Mars,\nwhere Faye's comet wheels and withdraws.\n\n_Of what do Comets consist?_\n\nThe unsolved problems pertaining to comets are very numerous and\nexceedingly delicate. Whence come they? Why did they not contract to\ncentres of nebul\u00e6? Are there regions where attractions are balanced,\nand matter is left to contract on itself, till the movements of\nsuns and planets adds or diminishes attractive force on one side,\nand so allows them to be drawn slowly toward one planet, and its\nsun, or another? There is ground for thinking that the comet of\n1866 and its train of meteors, visible to us in November, was thus\ndrawn into our system by the planet Uranus. Indeed, Leverrier has\nconjecturally fixed upon the date of A.D. 128 as the time when it\noccurred; but another and closer observation of its next return,\nin 1899, will be needed to give confirmation to the opinion. Our\nsun's authority extends at least half-way to the nearest fixed star,\none hundred thousand times farther than the orbit of the earth.\nMeteoric and cometary matter lying [Page 132] there, in a spherical\nshell about the solar system, balanced between the attraction of\ndifferent suns, finally feels the power that determines its destiny\ntoward our sun. It would take 167,000,000 years to come thence to\nour system.\n\nThe conditions of matter with which we are acquainted do not cover\nall the ground presented by these mysterious visitors. We know\na gas sixteen times as light as air, but hydrogen is vastly too\nheavy and dense; for we see the faintest star through thousands of\nmiles of cometary matter; we know that water may become cloudy vapor,\nbut a little of it obscures the vision. Into what more ethereal,\nand we might almost say spiritual, forms matter may be changed we\ncannot tell. But if we conceive comets to be only gas, it would\nexpand indefinitely in the realms of space, where there is no force\nof compression but its own. We might say that comets are composed\nof small separate masses of matter, hundreds of miles apart; and,\nlooking through thousands of miles of them, we see light enough\nreflected from them all to seem continuous. Doubtless that is sometimes\nthe case. But the spectroscope shows another state of things: it\nreveals in some of these comets an incandescent gas--usually some\nof the combinations of carbon. The conclusion, then, naturally is\nthat there are both gas and small masses of matter, each with an\norbit of its own nearly parallel to those of all the others, and\nthat they afford some attraction to hold the mass of intermingled and\nconfluent gas together. Our best judgment, then, is that the nucleus\nis composed of separate bodies, or matter in a liquid condition,\ncapable of being vaporized by the heat of the sun, and driven off,\n[Page 133] as steam from a locomotive, into a tail. Indications of\nthis are found in the fact that tails grow smaller at successive\nreturns, as the matter capable of such vaporization becomes\ncondensed. In some instances, as in that of the comet of 1843, the\nhead was diminished by the manufacture of a tail. On the other hand,\nProfessor Peirce showed that the nucleus of the comets of 1680,\n1843, and 1858 must have had a tenacity equal to steel, to prevent\nbeing pulled apart by the tidal forces caused by its terrible\nperihelion sweep around the sun.\n\nIt is likely that there are great varieties of condition in different\ncomets, and in the same comet at times. We see them but a few days\nout of the possible millions of their periodic time; we see them\nonly close to the sun, under the spur of its tremendous attraction\nand terrible heat. This gives us ample knowledge of the path of\ntheir orbit and time of their revolution, but little ground for\njudgment of their condition, when they slowly round the uttermost\ncape of their far-voyaging, in the terrible cold and darkness,\nto commence their homeward flight. The unsolved problems are not\nall in the distant sun and more distant stars, but one of them\nis carried by us, sometimes near, sometimes far off; but our\nacquaintance with the possible forms and conditions of matter is\ntoo limited to enable us to master the difficulties.\n\n_Will Comets strike the Earth?_\n\nVery likely, since one or two have done so within a recent period.\nWhat will be the effect? That depends on circumstances. There is\ngood reason to suppose we passed through the tail of a comet in\n1861, and the only [Page 134] observable effect was a peculiar\nphosphorescent mist. If the comet were composed of small meteoric\nmasses a brilliant shower would be the result. But if we fairly\nencountered a nucleus of any considerable mass and solidity, the\nresult would be far more serious. The mass of Donati's comet has\nbeen estimated by M. Faye to be 1/20000 of that of the earth. If\nthis amount of matter were dense as water, it would make a globe\nfive hundred miles in diameter; and if as dense as Professor Peirce\nproved the nucleus of this comet to be, its impact with the earth\nwould develop heat enough to melt and vaporize the hardest rocks.\nHappily there is little fear of this: as Professor Newcomb says, \"So\nsmall is the earth in comparison with celestial space, that if one\nwere to shut his eyes and fire at random in the air, the chance of\nbringing down a bird would be better than that of a comet of any\nkind striking the earth.\" Besides, we are not living under a\ngovernment of chance, but under that of an Almighty Father, who\nupholdeth all things by the word of his power; and no world can come\nto ruin till he sees that it is best.\n\n\n\n\n[Page 135]\nVIII.\n\nTHE PLANETS AS INDIVIDUALS.\n\n\"Through faith we understand that the worlds [plural] were framed\nby the word of God, so that things which were seen were not made\nof things which do appear.\"--_Heb._ xi. 3.\n\n[Page 136]\n\"O rich and various man! Thou palace of sight and sound, carrying\nin thy senses the morning, and the night, and the unfathomable\ngalaxy; in thy brain the geometry of the city of God; in thy heart\nthe power of love, and the realms of right and wrong. An individual\nman is a fruit which it costs all the foregoing ages to form and\nripen. He is strong, not to do but to live; not in his arms, but\nin his heart; not as an agent, but as a fact.\"--EMERSON.\n\n\n\n\n[Page 137]\nVII.\n\n_THE PLANETS AS INDIVIDUALS._\n\nHow many bodies there may be revolving about the sun we have no\nmeans to determine or arithmetic to express. When the new star\nof the American Republic appeared, there were but six planets\ndiscovered. Since then three regions of the solar system have been\nexplored with wonderful success. The outlying realms beyond Saturn\nyielded the planet Uranus in 1781, and Neptune in 1846. The middle\nregion between Jupiter and Mars yielded the little planetoid Ceres\nin 1801, Pallas in 1802, and one hundred and ninety others since.\nThe inner region between Mercury and the sun is of necessity full\nof small meteoric bodies; the question is, are there any bodies\nlarge enough to be seen?\n\nThe same great genius of Leverrier that gave us Neptune from the\nobserved perturbations of Uranus, pointed out perturbations in\nMercury that necessitated either a planet or a group of planetoids\nbetween Mercury and the sun. Theoretical astronomers, aided by the\nfact that no planet had certainly been seen, and that all asserted\ndiscoveries of one had been by inexperienced observers, inclined\nto the belief in a group, or that the disturbance was caused by\nthe matter reflecting the zodiacal light.\n\nWhen the total eclipse of the sun occurred in 1878, [Page 138]\nastronomers were determined that the question of the existence of an\nintra-mercurial planet should be settled. Maps of all the stars in\nthe region of the sun were carefully studied, sections of the sky\nabout the sun were assigned to different observers, who should\nattend to nothing but to look for a possible planet. It is now\nconceded that Professor Watson, of Ann Arbor, actually saw the\nsought-for body.\n\n\nVULCAN.\n\nThe god of fire; its sign [Symbol], his hammer.\n\nDISTANCE FROM THE SUN, 13,000,000 MILES. ORBITAL REVOLUTION, ABOUT\n20 DAYS.\n\n\nMERCURY.\n\nThe swift messenger of the gods; sign [Symbol], his caduceus.\n\nDISTANCE FROM THE SUN, 35,750,000 MILES. DIAMETER, 2992 MILES.\nORBITAL REVOLUTION, 87.97 DAYS. ORBITAL VELOCITY, 1773 MILES PER\nMINUTE. AXIAL REVOLUTION, 24H. 5M.\n\nMercury shines with a white light nearly as bright as Sirius; is\nalways near the horizon. When nearly between us and the sun, as\nat D (Fig. 46, p. 113), its illuminated side nearly opposite to\nus, we, looking from E, see only a thin crescent of its light.\nWhen it is at its greatest angular distance from the sun, as A or\nC, we see it illuminated like the half-moon. When it is beyond the\nsun, as at E, we see its whole illuminated face like the full-moon.\n\nThe variation of its apparent size from the varying distance is\nvery striking. At its extreme distance from the earth it subtends\nan angle of only five seconds; nearest to us, an angle of twelve\nseconds. Its distance from the earth varies nearly as one to three,\nand its apparent size in the inverse ratio.\n\n[Page 139]\nWhen Mercury comes between the earth and the sun, near the line\nwhere the planes of their orbits cut each other by reason of their\ninclination, the dark body of Mercury will be seen on the bright\nsurface of the sun. This is called a transit. If it goes across\nthe centre of the sun it may consume eight hours. It goes 100,000\nmiles an hour, and has 860,000 miles of disk to cross. The transit of\n1818 occupied seven and a half hours. The transits for the remainder\nof the century will occur:\n\n  November 7th   1881  |  November 10th   1894\n  May 9th        1891  |  November 4th    1901\n\n\nVENUS.\n\nGoddess of beauty; its sign [Symbol], a mirror.\n\nDISTANCE FROM THE SUN, 66,750,000 MILES. DIAMETER, 7660 MILES.\nORBITAL VELOCITY, 1296 MILES PER MINUTE. AXIAL REVOLUTION, 23H.\n21M. ORBITAL REVOLUTION, 224.7 DAYS.\n\nThis brilliant planet is often visible in the daytime. I was once\ndelighted by seeing Venus looking down, a little after mid-day\nthrough the open space in the dome of the Pantheon at Rome. It\nhas never since seemed to me as if the home of all the gods was\ndeserted. Phoebus, Diana, Venus and the rest, thronged through\nthat open upper door at noon of night or day. Arago relates that\nBonaparte, upon repairing to Luxemburg when the Directory was about\nto give him a _f\u00eate_, was much surprised at seeing the multitude\npaying more attention to the heavens above the palace than to him\nor his brilliant staff. Upon inquiry, he learned that these curious\npersons were observing with astonishment a star which they supposed\nto be that of the conqueror of Italy. The emperor himself was not\nindifferent when [Page 140] his piercing eye caught the clear lustre\nof Venus smiling upon him at mid-day.\n\nThis unusual brightness occurs when Venus is about five weeks before\nor after her inferior conjunction, and also nearest overhead by\nbeing north of the sun. This last circumstance occurs once in eight\nyears, and came on February 16th, 1878.\n\nVenus may be as near the earth as 22,000,000 miles, and as far\naway as 160,000,000. This variation of its distances from the earth\nis obviously much greater than that of Mercury, and its consequent\napparent size much more changeable. Its greatest and least apparent\nsizes are as ten and sixty-five (Fig. 53).\n\n[Illustration: Fig. 53.--Phases of Venus, and Varions Apparent\nDimensions.]\n\nWhen Copernicus announced the true theory of the solar system, he\nsaid that if the inferior planets could be clearly seen they would\nshow phases like the moon. When Galileo turned the little telescope\nhe had made on Venus, he confirmed the prophecy of Copernicus.\nDesiring to take time for more extended observation, and still be\nable to assert the priority of his discovery, he published the\nfollowing anagram, in which his discovery was contained:\n\n[Page 141]\n  \"H\u00e6c immatura a me jam frustra leguntur o. y.\"\n (These unripe things are now vainly gathered by me.)\n\nHe first saw Venus as gibbous; a few months revealed it as crescent,\nand then he transposed his anagram into:\n\n  \"Cynthi\u00e6 figuras \u00e6mulatur mater amorum.\"\n (The mother of loves imitates the phases of Cynthia.)\n\nMany things that were once supposed to be known concerning Venus are\nnot confirmed by later and better observations. Venus is surrounded\nby an atmosphere so dense with clouds that it is conceded that\nher time of rotation and the inclination of her axis cannot be\ndetermined. She revealed one of the grandest secrets of the universe\nto the first seeker; showed her highest beauty to her first ardent\nlover, and has veiled herself from the prying eyes of later comers.\n\nFlorence has built a kind of shrine for the telescope of Galileo.\nBy it he discovered the phases of Venus, the spots on the sun,\nthe mountains of the moon, the satellites of Jupiter, and some\nirregularities of shape in Saturn, caused by its rings. Galileo\nsubsequently became blind, but he had used his eyes to the best\npurpose of any man in his generation.\n\n\nTHE EARTH.\n\nIts sign [Symbol].\n\nDISTANCE FROM THE SUN, 92,500,000 MILES. DIAMETER, POLAR, 7899\nMILES; EQUATORIAL, 7925-1/2 MILES. AXIAL REVOLUTION, 23H. 56M.\n4.09S.; ORBITAL, 365.86. ORBITAL VELOCITY PER MINUTE, 1152.8 MILES.\n\nLet us lift ourselves up a thousand miles from the earth. We see it\nas a ball hung upon nothing in empty space. As the drop of falling\nwater gathers itself [Page 142] into a sphere by its own inherent\nattraction, so the earth gathers itself into a ball. Noticing\nclosely, we see forms of continents outlined in bright relief, and\noceanic forms in darker surfaces. We see that its axis of revolution\nis nearly perpendicular to the line of light from the sun. One-half\nis always dark. The sunrise greets a new thousand miles every hour;\nthe glories of [Page 143] the sunset follow over an equal space,\n180\u00b0 behind. We are glad that the darkness never overtakes the\nmorning.\n\n[Illustration: Fig. 54.--Earth and Moon in Space.]\n\n_The Aurora Borealis._\n\nWhile east and west are gorgeous with sunrise and sunset, the north\nis often more glorious with its aurora borealis. We remember that\nall worlds have weird and inexplicable appendages. They are not\nlimited to their solid surfaces or their circumambient air. The\nsun has its fiery flames, corona, zodiacal light, and perhaps a\nfiner kind of atmosphere than we know. The earth is\n[Page 144]\nnot without its inexplicable surroundings. It has not only its\ngorgeous eastern sunrise, its glorious western sunset, high above\nits surface in the clouds, but it also has its more glorious northern\ndawn far above its clouds and air. The realm of this royal splendor\nis as yet an unconquered world waiting for its Alexander. There are\ncertain observable facts, viz., it prevails mostly near the arctic\ncircle rather than the pole; it takes on various forms--cloud-like,\narched, straight; it streams like banners, waves like curtains in\nthe wind, is inconstant; is either the cause or result of electric\ndisturbance; it is often from four hundred to six hundred miles\nabove the earth, while our air cannot be over one hundred miles.\nIt almost seems like a revelation to human eyes of those vast,\nchangeable, panoramic pictures by which the inhabitants of heaven\nare taught.\n\n[Illustration: Fig. 55.--The Aurora as Waving Curtains.]\n\nInvestigation has discovered far more mysteries than it has explained.\nIt is possible that the same cause that produces sun-spots produces\naurora in all space, visible in all worlds. If so, we shall see\nmore abundant auroras at the next maximum of sun-spot, between\n1880-84.\n\n_The Delicate Balance of Forces._\n\nA soap-bubble in the wind could hardly be more flexible in form\nand sensitive to influence than is the earth. On the morning of\nMay 9th, 1876, the earth's crust at Peru gave a few great throbs\nupward, by the action of expansive gases within. The sea fled,\nand returned in great waves as the land rose and fell. Then these\nwaves fled away over the great mobile surface, and in less than\nfive hours they had covered a space equal to half of Europe. The\nwaves ran out to the Sandwich Islands, six [Page 145] thousand\nmiles, at the rate of five hundred miles an hour, and arrived there\nthirty feet high. They not only sped on in straight radial lines,\nbut, having run up the coast to California, were deflected away into\nthe former series of waves, making the most complex undulations.\nSimilar beats of the great heart of the earth have sent its pulses\nas widely and rapidly on previous occasions.\n\nThe figure of the earth, even on the ocean, is irregular, in consequence\nof the greater preponderance of land--and hence greater density--in the\nnorthern hemisphere. These irregularities are often very perplexing\nin making exact geodetic measurements. The tendency of matter to\nfly from the centre by reason of revolution causes the equatorial\ndiameter to be twenty-six, miles longer than the polar one. By this\nforce the Mississippi River is enabled to run up a hill nearly\nthree miles high at a very rapid rate. Its mouth is that distance\nfarther from the centre of the earth than its source, when but\nfor this rotation both points would be equally distant.\n\nIf the water became more dense, or if the world were to revolve\nfaster, the oceans would rush to the equator, burying the tallest\nmountains and leaving polar regions bare. If the water should become\nlighter in an infinitesimal degree, or the world rotate more slowly,\nthe poles would be submerged and the equator become an arid waste.\nNo balance, turning to 1/1000 of a grain, is more delicate than\nthe poise of forces on the world. Laplace has given us proof that\nthe period of the earth's axial rotation has not changed 1/100\nof a second of time in two thousand years.\n\n[Page 146]\n_Tides._\n\nBut there is an outside influence that is constantly acting upon\nthe earth, and to which it constantly responds. Two hundred and\nforty thousand miles from the earth is the moon, having 1/81 the\nmass of the world. Its attractive influence on the earth causes the\nmovable and nearer portions to hurry away from the more stable and\ndistant, and heap themselves up on that part of the earth nearest\nthe moon. Gravitation is inversely as the square of the distance;\nhence the water on the surface of the earth is attracted more than\nthe body of the earth, some parts of which are eight thousand miles\nfarther off; hence the water rises on the side next the moon. But\nthe earth, as a whole, is nearer the moon than the water on the\nopposite side, and being drawn more strongly, is taken away from\nthe water, leaving it heaped up also on the side opposite to the\nmoon.\n\nA subsidiary cause of tides is found in the revolution of the earth\nand moon about their common centre of gravity. Revolution about\nan axis through the centre of a sphere enlarges the equator by\ncentrifugal force. Revolution about an axis touching the surface\nof a flexible globe converts it into an egg-shaped body, with the\nlonger axis perpendicular to the axis of revolution. In Fig. 56 the\npoint of revolution is seen at the centre of gravity at G; hence,\nin the revolution of earth and moon as one, a strong centrifugal\nforce is caused at D, and a less one at C. This gives greater height\nto the tides than the attraction of the moon alone could produce.\n\n[Page 147]\n[Illustration: Fig. 56.]\n\nIf the earth had no axial revolution, the attractive point where\nthe tide rises would be carried around the earth once in twenty-seven\ndays by the moon's revolution about the earth. But since the earth\nrevolves on its axis, it presents a new section to the moon's attraction\nevery hour. If the moon were stationary, that would bring two high\ntides in exactly twenty-four hours; but as the moon goes forward,\nwe need nearly twenty-five hours for two tides.\n\nThe attractive influence of the sun also gives us a tide four-tenths\nas great as that of the moon. When these two influences of the sun\nand moon combine, as they do, in conjunction--when both bodies\nare on one side of the earth; or in opposition, sun and moon being\non opposite sides of the earth--we have spring or increased tides.\nWhen the moon is in its first or third quarter, _i. e._, when a\nline from the moon to the earth makes a right angle with one from\nthe sun to the earth, these influences antagonize one another,\nand we have the neap or low tides.\n\nIt is easy to see that if, when the moon was drawing its usual\ntide, the sun drew four-tenths of the water in a tide at right\nangles with it, the moon's tide must be by so much lower. Because\nof the inertia of the water [Page 148] it does not yield instantly\nto the moon's influence, and the crest of the tide is some hours\nbehind the advancing moon.\n\nThe amount of tide in various places is affected by almost innumerable\ninfluences, as distance of moon at its apogee or perigee; its position\nnorth, south, or at the equator; distance of earth from sun at\nperihelion and aphelion; the position of islands; the trend of\ncontinents, etc. All eastern shores have far greater tides than\nwestern. As the earth rolls to the east it leaves the tide-crest\nunder the moon to impinge on eastern shores, hence the tides of\nfrom seventy-five to one hundred feet in the Bay of Fundy. Lakes and\nmost seas are too small to have perceptible tides. The spring-tides\nin the Mediterranean Sea are only about three inches.\n\nThis constant ebb and flow of the great sea is a grand provision for\nits purification. Even the wind is sent to the sea to be cleansed.\nThe sea washes every shore, purifies every cove, bay, and river\ntwice every twenty-four hours. All putrescible matter liable to\nbreed a pestilence is carried far from shore and sunk under fathoms\nof the never-stagnant sea. The distant moon lends its mighty power\nto carry the burdens of commerce. She takes all the loads that\ncan be floated on her flowing tides, and cheerfully carries them\nin opposite directions in successive journeys.\n\nIt must be conceded that the profoundest study has not mastered\nthe whole philosophy of tides. There are certain facts which are\napparent, but for an explanation of their true theory such men as\nLaplace, Newton, and Airy have labored in vain. There are plenty\nof other worlds still to conquer.\n\n\n[Page 150]\n[Illustration: Fig. 57.--Lunar Day.]\n\n[Page 151]\nTHE MOON.\n\nNew moon, [Symbol]; first quarter, [Symbol]; full moon, [Symbol];\nlast quarter, [Symbol].\n\nEXTREME DISTANCE FROM THE EARTH, 259,600 MILES; LEAST, 221,000\nMILES; MEAN, 240,000 MILES. DIAMETER, 2164.6 MILES [2153, LOCKYER].\nREVOLUTION ABOUT THE EARTH, 29-1/2 DAYS. AXIAL REVOLUTION, SAME\nTIME.\n\nWhen the astronomer Herschel was observing the southern sky from\nthe Cape of Good Hope, the most clever hoax was perpetrated that\never was palmed upon a credulous public. Some new and wonderful\ninstruments were carefully described as having been used by that\nastronomer, whereby he was enabled to bring the moon so close that\nhe could see thereon trees, houses, animals, and men-like human\nbeings. He could even discern their movements, and gestures that\nindicated a peaceful race. The extent of the hoax will be perceived\nwhen it is stated that no telescope that we are now able to make\nreveals the moon more clearly than it would appear to the naked\neye if it was one hundred or one hundred and fifty miles away.\nThe distance at which a man can be seen by the unaided eye varies\naccording to circumstances of position, background, light, and\neye, but it is much inside of five miles.\n\nSince, however, the moon is our nearest neighbor, a member of our\nown family in fact, it is a most interesting object of study.\n\nA glance at its familiar face reveals its unequal illumination.\nAll ages and races have seen a man in the moon. All lovers have\nsworn by its constancy, and only part of them have kept their oaths.\nEvery twenty-nine or thirty days we see a silver crescent in the\nwest, and are glad if it comes over the right shoulder--so [Page\n152] much tribute does habit pay to superstition. The next night it\nis thirteen degrees farther east from the sun. We note the stars it\noccults, or passes by, and leaves behind as it broadens its disk,\ntill it rises full-orbed in the east when the sun sinks in the west.\nIt is easy to see that the moon goes around the earth from west to\neast. Afterward it rises later and smaller each night, till at\nlength, lost from sight, it rises about the same time as the sun,\nand soon becomes the welcome crescent new moon again.\n\nThe same peculiarities are always evident in the visible face of\nthe moon; hence we know that it always presents the same side to\nthe earth. Obviously it must make just one axial to one orbital\nrevolution. Hold any body before you at arm's-length, revolve it\none-quarter around you until exactly overhead. If it has not revolved\non an axis between the hands, another quarter of the surface is\nvisible; but if in going up it is turned a quarter over, by the\nhands holding it steady, the same side is visible. Three causes\nenable us to see a little more than half the moon's surface: 1. The\nspeed with which it traverses the ellipse of its orbit is variable.\nIt sometimes gets ahead of us, sometimes behind, and we see farther\naround the front or back part. 2. The axis is a little inclined to\nthe plane of its orbit, and its orbit a little inclined to ours;\nhence we see a little over its north pole, and then again over\nthe south pole. 3. The earth being larger, its inhabitants see\na little more than half-way around a smaller body. These causes\ncombined enable us to see 576/1000 of the moon's surface. Our eyes\nwill never see the other side of the moon. If, now, being solid,\nher axial revolution could [Page 153] be increased enough to make\none more revolution in two or three years, that difference between\nher axial and orbital revolution would give the future inhabitants\nof the earth a view of the entire circumference of the moon. Yet if\nthe moon were once in a fluid state, or had oceans on the surface,\nthe enormous tide caused by the earth would produce friction enough,\nas they moved over the surface, to gradually retard the axial\nrevolution till the two tidal elevations remained fixed toward and\nopposite the earth, and then the axial and orbital revolutions would\ncorrespond, as at present. In fact, we can prove that the form of\nthe moon is protuberant toward the earth. Its centre of gravity is\nthirty-three miles beyond its centre of magnitude, which is the same\nin effect as if a mountain of that enormous height rose on the earth\nside. Hence any fluid, as water or air, would flow round to the\nother side.\n\nThe moon's day, caused by the sun's light, is 29-1/2 times as long\nas ours. The sun shines unintermittingly for fifteen days, raising a\ntemperature as fervid as boiling water. Then darkness and frightful\ncold for the same time succeed, except on that half where the earth\nacts as a moon. The earth presents the same phases--crescent, full,\nand gibbous--to the moon as the moon does to us, and for the same\ncauses. Lord Rosse has been enabled, by his six-foot reflector, to\nmeasure the difference of heat on the moon under the full blaze\nof its noonday and midnight. He finds it to be no less than five\nhundred degrees. People not enjoying extremes of temperature should\nshun a lunar residence. The moon gives us only 1/6180000 as much\nlight as the sun. A sky full of moons would scarcely make daylight.\n\n[Page 154]\n[Illustration: Fig. 58.--View of the Moon near the Third Quarter.\nFrom a Photograph by Professor Henry Draper.]\n\nThere are no indications of air or water on the moon. When it occults\na star it instantly shuts off the light and as instantly reveals\nit again. An atmosphere would gradually diminish and reveal the\nlight, and by refraction [Page 155] cause the star to be hidden in\nmuch less time than the solid body of the moon would need to pass\nover it. If the moon ever had air and water, as it probably did,\nthey are now absorbed in the porous lava of its substance.\n\n_Telescopic Appearance._\n\n[Illustration: Fig. 59.--Illumination of Craters and Peaks.]\n\nProbably no one ever saw the moon by means of a good telescope\nwithout a feeling of admiration and awe. Except at full-moon, we\ncan see where the daylight struggles with the dark along the line\nof the moon's sunrise or sunset. This line is called the terminator.\nIt is broken in the extreme, because the surface is as rough as\npossible. In consequence of the small gravitation of the moon, utter\nabsence of the expansive power of ice shivering the cliffs, or the\nlevelling power of rains, precipices can stand in perpendicularity,\nmountains shoot up like needles, and cavities three miles deep\nremain unfilled. The light of the sun falling on the rough body\nof the moon, shown in section (Fig. 59), illuminates the whole\ncavity at _a_, part of the one at _b_, casts a long shadow from the\nmountain at _c_, and touches the tip of the one at _d_, which appears\nto a distant observer as a point of light beyond the terminator,\nAs the moon revolves the conical cavity, _a_ is illuminated on\nthe forward side only; the light creeps down the backward side\nof cavity _b_ to the bottom; mountain _c_. comes directly under\nthe sun and casts no shadow, and mountain _d_ casts its long shadow\nover the plain. Knowing the time of revolution, and observing the\nchange of [Page 156] illumination, we can easily measure the height\nof mountain and depth of crater. An apple, with excavations and\nadded prominences, revolved on its axis toward the light of a\ncandle, admirably illustrates the crescent light that fills either\nside of the cavities and the shadows of the mountains on the plain.\nNotice in Fig. 58 the crescent forms to the right, showing cavities\nin abundance.\n\n[Illustration: Fig. 60.--Lunar Crater \"Copernicus,\" after Secchi.]\n\nThe selenography of one side of the moon is much better known to\nus than the geography of the earth. Our maps of the moon are far\nmore perfect than those of the earth; and the photographs of lunar\nobjects by Messrs. Draper and De la Rue are wonderfully perfect,\n[Page 157] and the drawings of Padre Secchi equally so (Fig. 60).\nThe least change recognizable from the earth must be speedily\ndetected. There are frequently reports of discoveries of volcanoes\non the moon, but they prove to be illusions. The moon will probably\nlook the same to observers a thousand years hence as it does to-day.\n\nThis little orb, that is only 1/81 of the mass of the earth, has\ntwenty-eight mountains that are higher than Mont Blanc, that \"monarch\nof mountains,\" in Europe.\n\n_Eclipses._\n\n[Illustration: Fig. 61.--Eclipses; Shadows of Earth and Moon.]\n\nIt is evident that if the plane of the moon's orbit were to correspond\nwith that of the earth, as they all lie in the plane of the page\n(Fig. 61), the moon must pass between the centres of the earth\nand sun, and exactly behind the earth at every revolution. Such\nsuccessive and total darkenings would greatly derange all affairs\ndependent on light. It is easily avoided. Venus does [Page 158] not\ncross the disk of the sun at every revolution, because of the\ninclination of the plane of its orbit to that of the earth (see Fig.\n41, p. 107). So the plane of the orbit of the moon is inclined to\nthe orbit of the earth 5\u00b0 8' 39\"; hence the full-moon is often above\nor below the earth's shadow, and the earth is below or above the\nmoon's shadow at new moon. It is as if the moon's orbit were pulled\nup one-quarter of an inch from the page behind the earth, and\ndepressed as much below it between the earth and the sun. The point\nwhere the orbit of the moon penetrates the plane of the ecliptic is\ncalled a node. If a new moon occur when the line of intersection of\nthe planes of orbits points to the sun, the sun must be eclipsed; if\nthe full-moon occur, the moon must be eclipsed. In any other\nposition the sun or moon will only be partially hidden, or no\neclipse will occur.\n\nIf the new moon be near the earth it will completely obscure the\nsun. A dime covers it if held close to the eye. It may be so far\nfrom the earth as to only partially hide the sun; and, if it cover\nthe centre, leave a ring of sunlight on every side. This is called\nan annular eclipse. Two such eclipses will occur this year (1879).\nIf the full-moon passes near the earth, or is at perigee, it finds\nthe cone of shadow cast by the earth larger, and hence the eclipse\nis greater; if it is far from the earth, or near apogee, the earth's\nshadow is smaller, and the eclipse less, or is escaped altogether.\n\nThere is a certain periodicity in eclipses. Whenever the sun, moon,\nand earth are in a line, as in the total eclipse of July 29th,\n1878, they will be in the same position after the earth has made\nabout eighteen revolutions, [Page 159] and the moon two hundred and\nsixteen--that is, eighteen years after. This period, however, is\ndisregarded by astronomers, and each eclipse calculated by itself to\nthe accuracy of a second.\n\nHow terrible is the fear of ignorance and superstition when the sun\nor moon appear to be in the process of destruction! how delightful\nare the joys of knowledge when its prophesies in regard to the\nheavenly bodies are being fulfilled!\n\n\nMARS.\n\nThe god or war; Its sign [Symbol], spear and shield.\n\nMEAN DISTANCE FROM THE SUN, 141,000,000 MILES. DIAMETER, 4211 MILES.\nREVOLUTION, AXIAL, 24H. 37M. 22.7S.; ORBITAL, 686.98 DAYS. VELOCITY\nPER MINUTE, 899 MILES. SATELLITES, TWO.\n\n[Illustration: Fig. 62.--Apparent Size of Mars at Mean and Extreme\nDistances.]\n\nAt intervals, on an average of two years one month and nineteen\ndays, we find rising, as the sun goes down, the reddest star in\nthe heavens. Its brightness is exceedingly variable; sometimes\nit scintillates, and sometimes it shines with a steady light. Its\nmarked peculiarities demand a close study. We find it to be Mars,\nthe fiery god of war. Its orbit is far from circular. At perihelion\nit is 128,000,000 miles from the sun, and at aphelion 154,000,000;\nhence its mean distance is about 141,000,000. So great a change\nin its distance from the sun easily accounts for the change in\nits brilliancy. Now, if Mars and the earth revolved in circular\norbits, the one 141,000,000 miles from the sun, and the other\n92,000,000, they would approach at conjunction within 49,000,000\nmiles of each other, and at opposition be 233,000,000 miles apart.\nBut Mars at perihelion may be only 128,000,000 miles from the sun,\nand earth at [Page 160] aphelion may be 94,000,000 miles from the\nsun. They are, then, but 34,000,000 miles apart. This favorable\nopportunity occurs about once in seventy-nine years. At its last\noccurrence, in 1877, Mars introduced to us his two satellites, that\nhad never before been seen by man. In consequence of this greatly\nvarying distance, the apparent size of Mars differs very much (Fig.\n62). Take a favorable time when the planet is near, also as near\noverhead as it ever comes, so as to have as little atmosphere as\npossible to penetrate, and study the planet. The first thing that\nstrikes the observer is a dazzling spot of white near the pole which\nhappens to be toward him, or at both poles when the planet is so\nsituated that they can be seen. When the north pole is turned toward\nthe sun the size of the spot sensibly diminishes, and the spot at\nthe south pole enlarges, and _vice versa_. Clearly they are\nice-fields. Hence Mars has water, and air to carry it, and heat to\nmelt ice. It is winter at the south pole when Mars is farthest from\nthe sun; therefore the ice-fields are larger than at the north pole.\nIt is summer at the south pole when Mars is nearest the sun. Hence\nits ice-fields grow smaller [Page 161] than those of the north pole\nin its summer. This carrying of water from pole to pole, and melting\nof ice over such large areas, might give rise to uncomfortable\ncurrents in ocean and air; but very likely an inhabitant of earth\nmight be transported to the surface of Mars, and be no more\nsurprised at what he observed there than if he went to some point of\nthe earth to him unknown. Day and night would be nearly of the same\nlength; winter would linger longer in the lap of spring; summer\nwould be one hundred and eighty-one days long; but as the seas are\nmore intermingled with the land, and the divisions of land have less\nof continental magnitude, it may be conjectured that Mars might be a\ncomfortable place of residence to beings like men. Perhaps the\ngreatest surprise to the earthly visitor would be to find himself\nweighing only four-tenths as much as usual, able to leap twice as\nhigh, and lift considerable bowlders.\n\n_Satellites of Mars._\n\nThe night of August 11th, 1877, is famous in modern astronomy.\nMars has been a special object of study in all ages; but on that\nevening Professor Hall, of Washington, discovered a satellite of\nMars. On the 16th it was seen again, and its orbital motion followed.\nOn the following night it was hidden behind the body of the planet\nwhen the observation began, but at the calculated time--at four\no'clock in the morning--it emerged, and established its character as\na true moon, and not a fixed star or asteroid. Blessings, however,\nnever come singly, for another object soon emerged which proved\nto be an inner satellite. This is extraordinarily near [Page 162]\nthe planet--only four thousand miles from the surface--and its\nrevolution is exceedingly rapid. The shortest period hitherto known\nis that of the inner satellite of Saturn, 22h. 37m. The inner\nsatellite of Mars makes its revolution in 7h. 39m.--a rapidity so\nmuch surpassing the axial revolution of the planet itself, that it\nrises in the west and sets in the east, showing all phases of our\nmoon in one night. The outer satellite is 12,579 miles from Mars,\nand makes its revolution in 30h. 18m. Its diameter is six and a\nquarter miles; that of the inner one is seven and a half miles. This\ncan be estimated only by the amount of light given.\n\n\nASTEROIDS.\n\nALREADY DISCOVERED (1879), 192. DISTANCES FROM THE SUN, FROM 200,000,000\nTO 315,000,000 MILES. DIAMETERS, FROM 20 TO 400 MILES. MASS OF ALL,\nLESS THAN ONE-QUARTER OF THE EARTH.\n\nThe sense of infinite variety among the countless number of celestial\norbs has been growing rapidly upon us for half a century, and doubtless\nwill grow much more in half a century to come. Just as we paused\nin the consideration of planets to consider meteors and comets,\nat first thought so different, so must we now pause to consider a\nring of bodies, some of which are as small in comparison to Jupiter,\nthe next planet, as aerolites are compared to the earth.\n\nIn 1800 an association of astronomers, suspecting that a planet\nmight be found in the great distance between Mars and Jupiter,\ndivided the zodiac into twenty-four parts, and assigned one part to\neach astronomer for a thorough search; but, before their organization\ncould commence work, Piazzi, an Italian astronomer of Palermo, [Page\n163] found in Taurus a star behaving like a planet. In six weeks it\nwas lost in the rays of the sun. It was rediscovered on its\nemergence, and named Ceres. In March, 1802, a second planet was\ndiscovered by Olbers in the same gap between Mars and Jupiter, and\nnamed Pallas. Here was an embarrassment of richness. Olbers\nsuggested that an original planet had exploded, and that more pieces\ncould be found. More were found, but the theory is exploded into\nmore pieces than a planet could possibly be. Up to 1879 one hundred\nand ninety-two have been discovered, with a prospect of more.\nBetween 1871-75 forty-five were discovered, showing that they are\nsought for with great skill. In the discovery of these bodies, our\nAmerican astronomers, Professors Watson and Peters, are without\npeers.\n\nBetween Mars and Jupiter is a distance of some 339,000,000 miles.\nSubtract 35,000,000 miles next to Mars and 50,000,000 miles next\nto Jupiter, and there is left a zone 254,000,000 miles wide outside\nof which the asteroids never wander. If any ever did, the attraction\nof Mars or Jupiter may have prevented their return.\n\nSince the orbits of Mars and Jupiter show no sign of being affected\nby these bodies for a century past, it is probable that their number\nis limited, or at least that their combined mass does not approximate\nthe size of a planet. Professor Newcomb estimates that if all that\nare now discovered were put into one planet, it would not be over\nfour hundred miles in diameter; and if a thousand more should exist,\nof the average size of those discovered since 1850, their addition\nwould not increase the diameter to more than five hundred miles.\n\n[Page 164]\nThat all these bodies, which differ from each other in no respect\nexcept in brilliancy, can be noted and fixed so as not to be mistaken\none for another, and instantly recognized though not seen for a\ndozen years, is one of the highest exemplifications of the accuracy\nof astronomical observation.\n\n\nJUPITER.\n\nThe king of the gods; sign [Symbol], the bird of Jove.\n\nDISTANCE FROM THE SUN, PERIHELION, 457,000,000 MILES; APHELION,\n503,000,000 MILES. DIAMETER, EQUATORIAL, 87,500 MILES; POLAR, 82,500\nMILES. VOLUME, 1300 EARTHS. MASS, 213 EARTHS. AXIAL REVOLUTION, 9H.\n55M 20S. ORBITAL REVOLUTION, 11 YEARS 317 DAYS. VELOCITY, 483.6\nMILES PER MINUTE.\n\n[Illustration: Fig. 63.--Jupiter as seen by the great Washington\nTelescope. Drawn by Mr. Holden.]\n\nJupiter rightly wears the name of the \"giant planet.\" His orbit\nis more nearly circular than most smaller planets. He could not\nturn short corners with facility. We know little of his surface.\nHis spots and belts are [Page 165] changeable as clouds, which they\nprobably are. Some spots may be slightly self-luminous, but not the\npart of the planet we see. It is covered with an enormous depth of\natmosphere. Since the markings in the belts move about one hundred\nmiles a day, the Jovian tempests are probably not violent. It is,\nhowever, a singular and unaccountable fact, as remarked by Arago,\nthat its trade-winds move in an opposite direction from ours.\nJupiter receives only one twenty-seventh as much light and heat from\nthe sun as the earth receives. Its lighter density, being about that\nof water, indicates that it still has internal heat of its own.\nIndeed, it is likely that this planet has not yet cooled so as to\nhave any solid crust, and if its dense vapors could be deposited on\nthe surface, its appearance might be more suggestive of the sun than\nof the earth.\n\n_Satellites of Jupiter._\n\nIn one respect Jupiter seems like a minor sun--he is royally attended\nby a group of planets: we call them moons. This system is a favorite\nobject of study to everyone possessing a telescope. Indeed, I have\nknown a man who could see these moons with the naked eye, and give\ntheir various positions without mistake. Galileo first revealed\nthem to ordinary men. We see their orbits so nearly on the edge\nthat the moons seem to be sliding back and forth across and behind\nthe disk, and to varying distances on either side. Fig. 64 is the\nrepresentation of their appearance at successive observations in\nNovember, 1878. Their motion is so swift, and the means of comparison\nby one another and the planet so excellent, that they can be seen\nto change their places, [Page 166] be occulted, emerge from shadow,\nand eclipse the planet, in an hour's watching.\n\n[Illustration: Fig. 64.--_a._ Various Positions of Jupiter's Moons;\n_b._ Greatest Elongation of each Satellite.]\n\n                ELEMENTS OF JUPITER'S SATELLITES.\n +-------------------------------------------------------------+\n |               | Mean Distance |                  |          |\n |               | from Jupiter. | Sidereal Period. | Diameter.|\n |               |---------------+------------------+----------|\n |               |     Miles.    |  Days Hrs. Min.  |  Miles.  |\n |   I. Io       |     260,000   |    1   18   28   |   2,352  |\n |  II. Europa   |     414,000   |    3   13   43   |   2,099  |\n | III. Ganymede |     661,000   |    7    3   59   |   3,436  |\n |  IV. Callisto |   1,162,000   |   16   18    5   |   2,929  |\n +-------------------------------------------------------------+\n\nIt is seen by the above table that all these moons are larger than\nours, one larger than Mercury, and the asteroids are hardly large\nenough to make respectable moons for them. They differ in color:\nI. and II. have a bluish tinge; III. a yellow; and IV. is red.\nThe amount of light given by these satellites varies in the most\nsudden and inexplicable manner. Perhaps it may be owing to the\ndifferent distributions of land and water on them. The mass of all\nof them is .000171 of Jupiter.\n\n[Page 167]\nIf the Jovian system were the only one in existence, it would be\na surprising object of wonder and study. A monster planet, 85,000\nmiles in diameter, hung on nothing, revolving its equatorial surface\nforty-five miles a minute, holding four other worlds in steady\norbits, some of them at a speed of seven hundred miles a minute,\nand the whole system carried through space at five hundred miles\na minute. Yet the discovery of all this display of power, skill,\nand stability is only reading the easiest syllables of the vast\nliterature of wisdom and power.\n\n\nSATURN.\n\nThe god or time; sign [Symbol], his scythe.\n\nMEAN DISTANCE FROM THE SUN, 881,000,000 MILES. DIAMETER, POLAR,\n66,500 MILES; EQUATORIAL, 73,300 MILES. AXIAL REVOLUTION, 10H.\n14M. PERIODIC TIME, 29T YEARS. MOONS, EIGHT.\n\nThe human mind has used Saturn and the two known planets beyond\nfor the last 200 years as a gymnasium. It has exercised itself\nin comprehending their enormous distances in order to clear those\ngreater spaces, to where the stars are set; it has exercised its\ningenuity at interpreting appearances which signify something other\nthan they seem, in order that it may no longer be deluded by any\nsunrises into a belief that the heavenly dome goes round the earth.\nThat a wandering point of light should develop into such amazing\ngrandeurs under the telescope, is as unexpected as that every tiny\nseed should show peculiar markings and colors under the microscope.\n\n[Illustration: Fig. 65.--View of Saturn and his Rings.]\n\nThere are certain things that are easy to determine, such as size,\ndensity, periodic time, velocity, etc.; but other things are exceedingly\ndifficult to determine. It requires long sight to read when the\nbook is held [Page 168] 800,000,000 miles away. Only very few, if\nmore than two, opportunities have been found to determine the time\nof Saturn's rotation. On the evening of December 7th, 1870,\nProfessor Hall observed a brilliant white spot suddenly show itself\non the body of this planet. It was as if an eruption of white hot\nmatter burst up from the interior. It spread eastward, and remained\nbright till January, when it faded. No such opportunity for getting\na basis on which to found a calculation of the time of the rotation\nof Saturn has occurred since Sir William Herschel's observations;\nand, very singularly, the two times deduced wonderfully\ncoincide--that of Herschel being 10h. 16m., that of Mr. Hall being\n10h. 14m.\n\n[Page 169]\nThe density of Saturn is less than that of water, and its velocity\nof rotation so great that centrifugal force antagonizes gravitation\nto such an extent that bodies weigh on it about the same as on the\nearth. All the fine fancies of the habitability of this vaporous\nworld, all the calculations of the number of people that could\nlive on the square miles of the planet and its enormous rings,\nare only fancy. Nothing could live there with more brains than a\nfish, at most. It is a world in formative processes. We cannot hear\nthe voice of the Creator there, but we can see matter responsive\nto the voice, and moulded by his word.\n\n_Rings of Saturn._\n\nThe eye and mind of man have worked out a problem of marvellous\ndifficulty in finding a true solution of the strange appearance\nof the rings. Galileo has the immortal honor of first having seen\nsomething peculiar about this planet. He wrote to the Duke of Tuscany,\n\"When I view Saturn it seems _tricorps_. The central body seems the\nlargest. The two others, situated, the one on the east, and the\nother on the west, seem to touch it. They are like two supporters,\nwho help old Saturn on his way, and always remain at his side.\"\nLooking a few years later, the rings having turned from view, he\nsaid, \"It is possible that some demon mocked me;\" and he refused\nto look any more.\n\nHuyghens, in March, 1655, solved the problem of the triform appearance\nof Saturn. He saw them as handles on the two sides. In a year they\nhad disappeared, and the planet was as round as it seemed to Galileo\nin 1612. He did not, however, despair; and in October, [Page 170]\n1656, he was rewarded by seeing them appear again. He wrote of\nSaturn, \"It is girdled by a thin plain ring, nowhere touching,\ninclined to the ecliptic.\"\n\nSince that time discoveries have succeeded one another rapidly.\n\"We have seen by degrees a ring evolved out of a triform planet,\nand the great division of the ring and the irregularities on it\nbrought to light. Enceladus, and coy Mimas, faintest of twinklers,\nare caught by Herschel's giant mirrors. And he, too, first of men,\nrealizes the wonderful tenuity of the ring, along which he saw\nthose satellites travelling like pearls strung on a silver thread.\nThen Bond comes on the field, and furnishes evidence to show that\nwe must multiply the number of separate rings we know not how many\nfold. And here we reach the golden age of Saturnian discovery,\nwhen Bond, with the giant refractor of Cambridge, and Dawes, with\nhis 6-1/3-inch Munich glass, first beheld that wonderful dark\nsemi-transparent ring, which still remains one of the wonders of\nour system. But the end is not yet: on the southern surface of\nthe ring, ere summer fades into autumn, Otto Struve in turn comes\nupon the field, detects, as Dawes had previously done, a division\neven in the dark ring, and measures it, while it is invisible to\nLassell's mirror--a proof, if one were needed, of the enormous\nsuperiority possessed by refractors in such inquiries. Then we\napproach 1861, when the ring plane again passes through the earth,\nand Struve and Wray observe curious nebulous appearances.\"[*]\n\n[Footnote *: Lockyer.]\n\nOur opportunities for seeing Saturn vary greatly. As the earth at\none part of its orbit presents its south pole [Page 171] to the sun,\nthen its equator, then the north pole, so Saturn; and we, in the\ndirection of the sun, see the south side of the rings inclined at an\nangle of 27\u00b0; next the edge of the rings, like a fine thread of\nlight; then the north side at a similar inclination. On February\n7th, 1878, Saturn was between Aquarius and Pisces, with the edge of\nthe ring to the sun. In 1885, the planet being in Taurus, the south\nside of the rings will be seen at the greatest advantage. From 1881\ntill 1885 all circumstances will combine to give most favorable\nstudies of Saturn. Meanwhile study the picture of it. The outer ring\nis narrow, dark, showing hints of another division, sometimes more\nevident than at others, as if it were in a state of flux. The inner,\nor second, ring is much brighter, especially on the outer edge, and\nshading off to the dusky edge next to the planet. There is no sign\nof division into a third dusky innermost ring, as was plainly seen\nby Bond. This, too, may be in a state of flux.\n\nThe markings of the planet are delicate, difficult of detection,\nand are not like those stark zebra stripes that are so often\nrepresented.\n\nThe distance between the planet and the second ring seems to be\ndiminished one-half since 1657, and this ring has doubled its breadth\nin the same time. Some of this difference may be owing to our greater\ntelescopic power, enabling us to see the ring closer to the planet;\nbut in all probability the ring is closing in upon the central\nbody, and will touch it by A.D. 2150. Thus the whole ring must\nultimately fall upon the planet, instead of making a satellite.\n\nWe are anxious to learn the nature of such a ring. [Page 172]\nLaplace mathematically demonstrated that it cannot be uniform and\nsolid, and survive. Professor Peirce showed it could not be fluid,\nand continue. Then Professor Maxwell showed that it must be formed\nof clouds of satellites too small to be seen individually, and too\nnear together for the spaces to be discerned, unless, perhaps, we\nmay except the inner dark ring, where they are not near enough to\nmake it positively luminous. Indeed, there is some evidence that the\nmeteoroids are far enough apart to make the ring partially\ntransparent.\n\nWe look forward to the opportunities for observation in 1882 with\nthe brightest hope that these difficult questions will be solved.\n\n_Satellites of Saturn._\n\nThe first discovered satellite of Saturn seen by Huyghens was in\n1655, and the last by the Bonds, father and son, of Cambridge,\nin 1848. These are eight in number, and are named:\n\n                   Distant from Saturn's centre.\n     I. Mimas              119,725 miles.\n    II. Enceladus          153,630   \"\n   III. Tethys             190,225   \"\n    IV. Dione              243,670   \"\n     V. Rhea               340,320   \"\n    VI. Titan              788,915   \"\n   VII. Hyperion           954,160   \"\n  VIII. Japetus          2,292,790   \"\n\nTitan can be seen by almost any telescope; I., II., and III., only\nby the most powerful instrument. All except Japetus revolve nearly\nin the plane of the ring. Like the moons of Jupiter, they present\nremarkable and unaccountable variations of brilliancy. An inspection\n[Page 173] of the table reveals either an expectation that another\nmoon will be discovered between V. and VI., and about three more\nbetween VII. and VIII., or that these gaps may be filled with groups\nof invisible asteroids, as the gap between Mars and Jupiter. This\nwill become more evident by drawing Saturn, the rings, and orbits of\nthe moons all as circles, on a scale of 10,000 miles to the inch.\nSaturn will be in the centre, 70,000 miles in diameter; then a gap,\ndecreasing twenty-nine miles a year to the first ring, of, say,\n10,000 miles; a dark ring 9000 miles wide; next the brightest ring\n18,300 miles wide; then a gap of 1750 miles; then the outer ring\n10,000 miles wide; then the orbits of the satellites in order.\n\nIf the scenery of Jupiter is magnificent, that of Saturn must be\nsublime. If one could exist there, he might wander from the illuminated\nside of the rings, under their magnificent arches, to the darkened\nside, see the swift whirling moons; one of them presenting ten times\nthe disk of the earth's moon, and so very near as to enable him\nto watch the advancing line of light that marks the lunar morning\njourneying round that orb.\n\n\nURANUS.\n\nSign [Symbol]; the initial of Herschel, and sign of the world.\n\nDISTANCE FROM THE SUN, 1,771,000,000 MILES. DIAMETER, 31,700 MILES.\nAXIAL REVOLUTION UNKNOWN. ORBITAL, 84 YEARS. VELOCITY PER MINUTE,\n252 MILES. MOONS, FOUR.\n\nUranus was presented to the knowledge of man as an unexpected reward\nfor honest work. It was first mistaken by its discoverer for a comet,\na mere cloud of vapor; but it proved to be a world, and extended the\n[Page 174] boundaries of our solar system, in the moment of its\ndiscovery, as much as all investigation had done in all previous\nages.\n\nSir William Herschel was engaged in mapping stars in 1781, when he\nfirst observed its sea-green disk. He proposed to call it _Georgium\nSidus_, in honor of his king; but there were too many names of the\ngods in the sky to allow a mortal name to be placed among them. It\nwas therefore called Uranus, since, being the most distant body of\nour system, as was supposed, it might appropriately bear the name\nof the oldest god. Finding anything in God's realms of infinite\nriches ought not to lead men to regard that as final, but as a\npromise of more to follow.\n\nThis planet had been seen five times by Flamsteed before its character\nwas determined--once nearly a century before--and eight times by\nLe Monnier. These names, which might easily have been associated\nwith a grand discovery, are associated with careless observation.\nEyes were made not only to be kept open, but to have minds behind\nthem to interpret their visions. Herschel thought he discovered six\nmoons belonging to Uranus, but subsequent investigation has limited\nthe number to four. Two of these are seen with great difficulty by\nthe most powerful telescopes.\n\nIf the plane of our moon's orbit were tipped up to a greater\ninclination, revolving it on the line of nodes as an axis until\nit was turned 85\u00b0, the moon, still continuing on its orbit in that\nplane, would go over the poles instead of about the equator, and\nwould go back to its old path when the plane was revolved 180\u00b0;\nbut its revolution would now be from east to west, or [Page 175]\nretrograde. The plane of the moons of Uranus has been thus inclined\ntill it has passed 10\u00b0 beyond the pole, and the moons' motions are\nretrograde as regards other known celestial movements. How Uranus\nitself revolves is not known. There are more worlds to conquer.\n\n\nNEPTUNE.\n\nGod of the sea; sign [Symbol], his trident.\n\nDISTANCE FROM THE SUN, 2,775,000,000 MILES. DIAMETER, 34,500 MILES.\nVELOCITY PER MINUTE, 201.6 MILES. AXIAL REVOLUTION UNKNOWN. ORBITAL,\n164.78 YEARS. ONE MOON.\n\nMen sought for Neptune as the heroes sought the golden fleece.\nThe place of Uranus had been mapped for nearly one hundred years\nby these accidental observations. On applying the law of universal\ngravitation, a slight discrepancy was found between its computed\nplace and its observed place. This discrepancy was exceedingly\nslight. In 1830 it was only 20\"; in 1840,190\"; in 1884, 2'. Two\nstars that were 2' apart would appear as one to the keenest unaided\neye, but such an error must not exist in astronomy. Years of work\nwere given to its correction. Mr. John C. Adams, of Cambridge,\nEngland, finding that the attraction of a planet exterior to Uranus\nwould account for its irregularities, computed the place of such\na hypothetical body with singular exactness in October, 1841; but\nneither he nor the royal astronomer Airy looked for it. Another\nopportunity for immortality was heedlessly neglected. Meanwhile,\nM. Leverrier, of Paris, was working at the same problem. In the\nsummer of 1846 Leverrier announced the place of the exterior planet.\nThe conclusion was in striking coincidence with that of Mr. [Page\n176] Clark. Mr. Challis commenced to search for the planet near the\nindicated place, and actually saw and mapped the star August 4th,\n1846, but did not recognize its planetary character. Dr. Galle, of\nBerlin, on the 23d of September, 1846, found an object with a\nplanetary disk not plotted on the map of stars. It was the\nsought-for world. It would seem easy to find a world seventy-six\ntimes as large as the earth, and easy to recognize it when seen. The\nfact that it could be discovered only by such care conveys an\noverwhelming idea of the distance where it moves.\n\n[Illustration: Fig. 66.--Perturbation of Uranus.]\n\nThe effect of these perturbations by an exterior planet is understood\nfrom Fig. 66. Uranus and Neptune were in conjunction, as shown,\nin 1822. But in 1820 it had been found that Uranus was too far\nfrom the sun, and too much accelerated. Since 1800, Neptune, in\nhis orbit from F to E, had been hastening Uranus in his orbit D\nfrom C to B, and also drawing it farther from the sun. After 1822,\nNeptune, in passing from E to D, had been retarding Uranus in his\norbit from B to A.\n\nWe have seen it is easy to miss immortality. There is still another\ninstance. Lalande saw Neptune on May 8th and 10th, 1795, noted that\nit had moved a little, and that the observations did not agree;\nbut, supposing the first was wrong, carelessly missed the glory\nof once more doubling the bounds of the empire of the sun.\n\n[Page 177]\nIt is time to pause and review our knowledge of this system. The\nfirst view reveals a moon and earth endowed with a force of inertia\ngoing on in space in straight lines; but an invisible elastic cord of\nattraction holds them together, just counterbalancing this tendency\nto fly apart, and hence they circle round their centre of gravity.\nThe revolving earth turns every part of its surface to the moon in\neach twenty-four hours. By an axial revolution in the same time\nthat the moon goes round the earth, the moon holds the same point\nof its surface constantly toward the earth. If we were to add one,\ntwo, four, eight moons at appropriate distances, the result would\nbe the same. There is, however, another attractive influence--that\nof the sun. The sun attracts both earth and moon, but their nearer\naffection for each other keeps them from going apart. They both,\nrevolving on their axes and around their centre of gravity, sweep\nin a vastly wider curve around the sun. Add as many moons as has\nJupiter or Saturn, the result is the same--an orderly carrying\nof worlds through space.\n\nThere lies the unsupported sun in the centre, nearer to infinity\nin all its capacities and intensities of force than our minds can\nmeasure, filling the whole dome to where the stars are set with\nlight, heat, and power. It holds five small worlds--Vulcan, Mercury,\nVenus, Earth, and Mars--within a space whose radius it would require\na locomotive half a thousand years to traverse. It next holds some\nindeterminate number of asteroids, and the great Jupiter, equal in\nvolume to 13,000 earths. It holds Saturn, Uranus, and Neptune, and\nall their variously related satellites and rings. The two thoughts\nthat overwhelm us are distance and power. The period of [Page 178]\nman's whole history is not sufficient for an express train to\ntraverse half the distance to Neptune. Thought wearies and fails in\nseeking to grasp such distances; it can scarcely comprehend one\nmillion miles, and here are thousands of them. Even the wings of\nimagination grow weary and droop. When we stand on that outermost of\nplanets, the very last sentinel of the outposts of the king, the\nvery sun grown dim and small in the distance, we have taken only one\nstep of the infinite distance to the stars. They have not changed\ntheir relative position--they have not grown brighter by our\napproach. Neptune carries us round a vast circle about the centre of\nthe dome of stars, but we seem no nearer its sides. In visiting\nplanets, we have been only visiting next-door neighbors in the\nstreets of a seaport town. We know that there are similar neighbors\nabout Sirius and Arcturus, but a vast sea rolls between. As we said,\nwe stand with the outermost sentinel; but into the great void beyond\nthe king of day sends his comets as scouts, and they fly thousands\nof years without for one instant missing the steady grasp of the\npower of the sun. It is nearer almightiness than we are able to\nthink.\n\nIf we cannot solve the problems of the present existence of worlds,\nhow little can we expect to fathom the unsoundable depths of their\ncreation and development through ages measureless to man! Yet the\nvery difficulty provokes the most ambitious thought. We toil at\nthe problem because it has been hitherto unsolvable. Every error\nwe make, and discover to be such, helps toward the final solution.\nEvery earnest thinker who climbs the shining worlds as steps to\na higher thought is trying to solve the problem God has given us\nto do.\n\n\n\n\n[Page 179]\nIX.\n\nTHE NEBULAR HYPOTHESIS.\n\n\"And the earth was without form, and void; and darkness was upon\nthe face of the deep.\"--_Genesis_ i. 2.\n\n[Page 180]\n                                \"A dark\n    Illimitable ocean, without bound,\n    Without dimension, where length, breadth, and height,\n    And time, and place are lost.\"--MILTON.\n\n\"It is certain that matter is somehow directed, controlled, and\narranged; while no material forces or properties are known to be\ncapable of discharging such functions.\"--LIONEL BEALE.\n\n\"The laws of nature do not account for their own origin.\"--JOHN\nSTUART MILL.\n\n\n\n\n[Page 181]\nIX.\n\n_THE NEBULAR HYPOTHESIS._\n\nThe method by which the solar system came into its present form\nwas sketched in vast outline by Moses. He gave us the fundamental\nidea of what is called the nebular hypothesis. Swedenborg, that\nprodigal dreamer of vagaries, in 1734 threw out some conjectures of\nthe way in which the outlines were to be filled up; Buffon followed\nhim closely in 1749; Kant sought to give it an ideal philosophical\ncompleteness; as he said, \"not as the result of observation and\ncomputation,\" but as evolved out of his own consciousness; and\nLaplace sought to settle it on a mathematical basis.\n\nIt has been modified greatly by later writers, and must receive\nstill greater modifications before it can be accepted by the best\nscientists of to-day. It has been called \"the grandest generalization\nof the human mind;\" and if it shall finally be so modified as to pass\nfrom a tentative hypothesis to an accepted philosophy, declaring\nthe modes of a divine worker rather than the necessities of blind\nforce, it will still be worthy of that high distinction.\n\nLet it be clearly noted that it never proposes to do more than to\ntrace a portion of the mode of working which brought the universe\nfrom one stage to another. It only goes back to a definite point,\nnever to absolute beginning, nor to nothingness. It takes matter\nfrom [Page 182] the hand of the unseen power behind, and merely\nnotes the progress of its development. It finds the clay in the\nhands of an intelligent potter, and sees it whirl in the process of\nformation into a vessel. It is not in any sense necessarily\natheistic, any more than it is to affirm that a tree grows by vital\nprocesses in the sun and dew, instead of being arbitrarily and\ninstantly created. The conclusion reached depends on the spirit of\nthe observer. Newton could say, \"This most beautiful system of the\nsun, planets, and comets could only proceed from the counsel and\ndominion of an intelligent and powerful being!\" Still it is well to\nrecognize that some of its most ardent defenders have advocated it\nas materialistic. And Laplace said of it to Napoleon, \"I have no\nneed of the hypothesis of a god.\"\n\nThe materialistic statement of the theory is this: that matter\nis at first assumed to exist as an infinite cloud of fire-mist,\ndowered with power latent therein to grow of itself into every\npossibility of world, flower, animal, man, mind, and affection,\nwithout any interference or help from without. But it requires\nfar more of the Divine Worker than any other theory. He must fill\nmatter with capabilities to take care of itself, and this would\ntax the abilities of the Infinite One far more than a constant\nsupervision and occasional interference. Instead of making the\nvase in perfect form, and coloring it with exquisite beauty by\nan ever-present skill, he must endow the clay with power to make\nitself in perfect form, adorn itself with delicate beauty, and\ncreate other vases.\n\nThe nebular hypothesis is briefly this: All the matter composing\nall the bodies of the sun, planets, and satellites once existed\nin an exceedingly diffused state; [Page 183] rarer than any gas with\nwhich we are acquainted, filling a space larger than the orbit of\nNeptune. Gravitation gradually contracted this matter into a\ncondensing globe of immense extent. Some parts would naturally be\ndenser than others, and in the course of contraction a rotary\nmotion, it is affirmed, would be engendered. Rotation would flatten\nthe globe somewhat in the line of its axis. Contracting still more,\nthe rarer gases, aided by centrifugal force, would be left behind as\na ring that would ultimately be separated, like Saturn's ring, from\nthe retreating body. There would naturally be some places in this\nring denser than others; these would gradually absorb all the ring\ninto a planet, and still revolve about the central mass, and still\nrotate on its own axis, throwing off rings from itself. Thus the\nplanet Neptune would be left behind in the first sun-ring, to make\nits one moon; the planet Uranus left in the next sun-ring, to make\nits four moons from four successive planet-rings; Saturn, with its\neight moons and three rings not made into moons, is left in the\nthird sun-ring; and so on down to Vulcan.\n\nThe outer planets would cool off first, become inhabitable, and,\nas the sun contracted and they radiated their own heat, become\nrefrigerated and left behind by the retreating sun. Of course the\nouter planets would move slowly; but as that portion of the sun\nwhich gave them their motion drew in toward the centre, keeping\nits absolute speed, and revolving in the lessening circles of a\ncontracting body, it would give the faster motion necessary to\nbe imparted to Earth, Mercury, and Vulcan.\n\nThe four great classes of facts confirmatory of this hypothesis\nare as follows: 1st. All the planets move [Page 184] in the same\ndirection, and nearly in the same plane, as if thrown off from one\nequator; 2d. The motions of the satellites about their primaries are\nmostly in the same direction as that of their primaries about the\nsun; 3d. The rotation of most of these bodies on their axes, and\nalso of the sun, is in the same direction as the motion of the\nplanets about the sun; 4th. The orbits of the planets, excluding\nasteroids, and their satellites, have but a comparatively small\neccentricity; 5th. Certain nebul\u00e6 are observable in the heavens\nwhich are not yet condensed into solids, but are still bright gas.\n\nThe materialistic evolutionist takes up the idea of a universe of\nmaterial world-stuff without form, and void, but so endowed as to\ndevelop itself into orderly worlds, and adds to it this exceeding\nadvance, that when soil, sun, and chemical laws found themselves\nproperly related, a force in matter, latent for a million eons in\nthe original cloud, comes forward, and dead matter becomes alive\nin the lowest order of vegetable life; there takes place, as Herbert\nSpencer says, \"a change from an indefinite, incoherent homogeneity,\ninto a definite, coherent heterogeneity, through continuous\ndifferentiation and integration.\" The dead becomes alive; matter\npasses from unconsciousness to consciousness; passes up from plant\nto animal, from animal to man; takes on power to think, reason,\nlove, and adore. The theistic evolutionist may think that the same\nprocess is gone through, but that an ever-present and working God\nsuperintends, guides, and occasionally bestows a new endowment\nof power that successively gives life, consciousness, mental,\naffectional, and spiritual capacity.\n\nIs this world-theory true? and if so, is either of the [Page 185]\nevolution theories true also? If the first evolution theory is true,\nthe evolved man will hardly know which to adore most, the Being that\ncould so endow matter, or the matter capable of such endowment.\n\nThere are some difficulties in the way of the acceptance of the\nnebular hypothesis that compel many of the most thorough scientists\nof the day to withhold their assent to its entirety. The latest, and\none of the most competent writers on the subject, Professor Newcomb,\nwho is a mathematical astronomer, and not an easy theorist, evolving\nthe system of the universe from the depth of his own consciousness,\nsays: \"Should any one be sceptical as to the sufficiency of these\nlaws to account for the present state of things, science can furnish\nno evidence strong enough to overthrow his doubts until the sun\nshall be found to be growing smaller by actual measurement, or the\nnebul\u00e6 be actually seen to condense into stars and systems.\" In\none of the most elaborate defences of the theory, it is argued that\nthe hypothesis explains why only one of the four planets nearest\nthe sun can have a moon, and why there can be no planet inside of\nMercury. The discovery of the two satellites to Mars and of the\nplanet Vulcan makes it all the worse for these facts.\n\nSome of the objections to the theory should be known by every thinker.\nLaplace must have the cloud \"diffused in consequence of excessive\nheat,\" etc. Helmholtz, in order to account for the heat of the\ncontracting sun, must have the cloud relatively cold. How he and\nhis followers diffused the cloud without heat is not stated.\n\nThe next difficulty is that of rotation. The laws [Page 186] of\nscience compel a contraction into one non-rotating body--a central\nsun, indeed, but no planets about it. Laplace cleverly evades the\ndifficulty by not taking from the hand of the Creator diffused gas,\nbut a sun with an atmosphere filling space to the orbit of Neptune,\nand _already in revolution_. He says: \"It is four millions to one\nthat all motions of the planets, rotations and revolutions, were at\nonce imparted by an original common cause, of which we know neither\nthe nature nor the epoch.\" Helmholtz says of rotation, \"the\nexistence of which must be assumed.\" Professor Newcomb says that the\nplanets would not be arranged as now, each one twice as far from the\nsun as the next interior one, and the outer ones made first, but\nthat all would be made into planets at once, and the small inner\nones quite likely to cool off more rapidly.\n\nIt is a very serious difficulty that at least one satellite does\nnot revolve in the right direction. How Neptune or Uranus could\nthrow their moons backward from its equator is not easily accounted\nfor. It is at least one Parthian arrow at the system, not necessarily\nfatal, but certainly dangerous.\n\nA greater difficulty is presented by the recently discovered satellites\nof Mars. The inner one goes round the planet in one-third part of\nthe time of the latter's revolution. How Mars could impart three\ntimes the speed to a body flying off its surface that it has itself,\nhas caused several defenders of the hypothesis to rush forward\nwith explanations, but none with anything more than mere imaginary\ncollisions with some comet. It is to be noticed that accounting for\nthree times the speed is not enough; for as Mars shrunk away from\nthe [Page 187] ring that formed that satellite, it ought itself to\nattain more speed, as the sun revolves faster than its planets, and\nthe earth faster than its moon. In defending the hypothesis, Mitchel\nsaid: \"Suppose we had discovered that it required more time for\nSaturn or Jupiter to rotate on their axes than for their nearest\nmoon to revolve round them in its orbit; this would have falsified\nthe theory.\" It is also asserted that the newly discovered planet\nVulcan makes an orbital in less time than the sun makes an axial\nrevolution.\n\nIn regard to one Martial moon, Professor Kirkwood, on whom Proctor\nconferred the highest title that could be conferred, \"the modern\nKepler,\" says: \"Unless some explanation can be given, the short period\nof the inner satellite will be doubtless regarded as a conclusive\nargument against the nebular hypothesis.\" If gravitation be sufficient\nto account for the various motions of the heavenly bodies, we have\na perplexing problem in the star known as 1830 Groombridge, now\nin the Hunting Dogs of Bootes. It is thought to have a speed of\ntwo hundred miles per second--a velocity that all the known matter\nin the universe could not give to the star by all its combined\nattraction. Neither could all that attraction stop the motion of\nthe star, or bend it into an orbit. Its motion must be accounted\nfor on some hypothesis other than the nebular.\n\nThe nebul\u00e6 which we are able to observe are not altogether confirmatory\nof the hypothesis under consideration. They have the most fantastic\nshapes, as if they had no relation to rotating suns in the formative\nstages. There are vast gaps in the middle, where they ought to be\ndensest. Mr. Plumer, in the _Natural Science Review_, [Page 188]\nsays, in regard to the results of the spectroscopic revelations: \"We\nare furnished with distinct proof that the gases so examined are not\nonly of nearly equal density, but that they exist in a low state of\n_tension. This fact is fatal to the nebular theory._\"\n\nIn the autumn of 1876 a star blazed out in Cygnus, which promised\nto throw a flood of light on the question of world-making. Its\nspectrum was like some of the fixed stars. It probably blazed ont\nby condensation from some previously invisible nebula. But its\nbrilliancy diminished swiftly, when it ought to have taken millions\nof years to cool. If the theory was true, it ought to have behaved\nvery differently. It should have regularly condensed from gas to a\nsolid sun by slow process. But, worst of all, after being a star\nawhile, it showed unmistakable proofs of turning into a cloud-mist--a\nstar into a nebula, instead of _vice versa_. A possible explanation\nwill be considered under variable stars.\n\nSuch are a few of the many difficulties in the way of accepting\nthe nebular hypothesis, as at present explained, as being the true\nmode of development of the solar system. Doubtless it has come\nfrom a hot and diffused condition into its present state; but when\nsuch men as Proctor, Newcomb, and Kirkwood see difficulties that\ncannot be explained, contradictions that cannot be reconciled by\nthe principles of this theory, surely lesser men are obliged to\nsuspend judgment, and render the Scotch verdict of \"not proven.\"\nWhatever truth there may be in the theory will survive, and be\nincorporated into the final solution of the problem; which solution\nwill be a much grander generalization of the human mind than the\nnebular hypothesis.\n\n[Page 189]\nOf some things we feel very sure: that matter was once without\nform and void, and darkness rested on the face of the mighty deeps;\nthat, instead of chaos, we have now cosmos and beauty; and that\nthere is some process by which matter has been brought from one\nstate to the other. Whether, however, the nebular hypothesis lays\ndown the road travelled to this transfiguration, we are not sure.\nSome of it seems like solid rock, and some like shifting quicksand.\nDoubtless there is a road from that chaos to this fair cosmos.\nThe nebular hypothesis has surveyed, worked, and perfected many\nlong reaches of this road, but the rivers are not bridged, the\nchasms not filled, nor the mountains tunnelled.\n\nWhen men attempt to roll the hypothesis of evolution along the\nroad of the nebular hypothesis of worlds, and even beyond to the\nproduction of vegetable and animal life, mind and affection, the\ngaps in the road become evident, and disastrous.\n\nA soul that has reached an adoration for the Supreme Father cares\nnot how he has made him. Doubtless the way God chose was the best.\nIt is as agreeable to have been thought of and provided for in the\nbeginning, to have had a myriad ages of care, and to have come\nfrom the highest existent life at last, as to have been made at\nonce, by a single act, out of dust. The one who is made is not to\nsay to the Maker, \"Why hast thou formed me in this or that manner?\"\nWe only wish the question answered in what manner we were really\nmade.\n\nEvolution, without constant superintendence and occasional new\ninspiration of power, finds some tremendous chasms in the road\nit travels. These must be spanned by the power of a present God\nor the airy imagination [Page 190] of man. Dr. McCosh has happily\nenumerated some of these tremendous gaps over which mere force\ncannot go. Given, then, matter with mechanical power only, what are\nthe gaps between it and spirituality?\n\n\"1. Chemical action cannot be produced by mechanical power.\n\n\"2. Life, even in the lowest forms, cannot be produced from unorganized\nmatter.\n\n\"3. Protoplasm can be produced only by living matter.\n\n\"4. Organized matter is made up of cells, and can be produced only\nby cells. Whence the first cell?\n\n\"5. A living being can be produced only from a seed or germ. Whence\nthe first vegetable seed?\n\n\"6. An animal cannot be produced from a plant. Whence the first\nanimal?\n\n\"7. Sensation cannot be produced in insentient matter.\n\n\"8. The genesis of a new species of plant or animal has never come\nunder the cognizance of man, either in pre-human or post-human ages,\neither in pre-scientific or scientific times. Darwin acknowledges\nthis, and says that, should a new species suddenly arise, we have\nno means of knowing that it is such.\n\n\"9. Consciousness--that is, a knowledge of self and its\noperations--cannot be produced out of mere matter or sensation.\n\n\"10. We have no knowledge of man being generated out of the lower\nanimals.\n\n\"11. All human beings, even savages, are capable of forming certain\nhigh ideas, such as those of God and duty. The brute creatures\ncannot be made to entertain these by any training.\n\n[Page 191]\n\"With such tremendous gaps in the process, the theory which would\nderive all things out of matter by development is seen to be a\nvery precarious one.\n\nThe truth, according to the best judgment to be formed in the present\nstate of knowledge, would seem to be about this: The nebular hypothesis\nis correct in all the main facts on which it is based; but that neither\nthe present forces of matter, nor any other forces conceivable to\nthe mind of man, with which it can possibly be endowed, can account\nfor all the facts already observed. There is a demand for a personal\nvolition, for an exercise of intelligence, for the following of a\ndivine plan that embraces a final perfection through various and\nchangeful processes. The five great classes of facts that sustain\nthe nebular hypothesis seem set before us to show the regular order\nof working. The several facts that will not, so far as at present\nknown, accord with that plan, seem to be set before us to declare\nthe presence of a divine will and power working his good pleasure\naccording to the exigencies of time and place.\n\n\n\n\n[Page 193]\nX.\n\nTHE STELLAR SYSTEM.\n\n\"The heavens number out the glory of the strong God.\"--DAVID.\n\n[Page 194]\nRichter says that \"an angel once took a man and stripped him of\nhis flesh, and lifted him up into space to show him the glory of\nthe universe. When the flesh was taken away the man ceased to be\ncowardly, and was ready to fly with the angel past galaxy after\ngalaxy, and infinity after infinity, and so man and angel passed\non, viewing the universe, until the sun was out of sight--until\nour solar system appeared as a speck of light against the black\nempyrean, and there was only darkness. And they looked onward,\nand in the infinities of light before, a speck of light appeared,\nand suddenly they were in the midst of rushing worlds. But they\npassed beyond that system, and beyond system after system, and\ninfinity after infinity, until the human heart sank, and the man\ncried out: 'End is there none of the universe of God?' The angel\nstrengthened the man by words of counsel and courage, and they flew\non again until worlds left behind them were out of sight, and specks\nof light in advance were transformed, as they approached them, into\nrushing systems; they moved over architraves of eternities, over\npillars of immensities, over architecture of galaxies, unspeakable in\ndimensions and duration, and the human heart sank again and called\nont: 'End is there none of the universe of God?' And all the stars\nechoed the question with amazement: 'End is there none of the universe\nof God?' And this echo found no answer. They moved on again past\nimmensities of immensities, and eternities of eternities, until\nin the dizziness of uncounted galaxies the human heart sank for\nthe last time, and called out: 'End is there none of the universe\nof God?' And again all the stars repeated the question, and the\nangel answered: 'End is there none of the universe of God. Lo,\nalso, there is no beginning.'\"\n\n\n\n\n[Page 195]\nX.\n\n_THE OPEN PAGE OF THE HEAVENS._\n\nThe Greeks set their mythological deities in the skies, and read\nthe revolving pictures as a starry poem. Not that they were the\nfirst to set the blazonry of the stars as monuments of their thought;\nwe read certain allusions to stars and asterisms as far back as\nthe time of Job. And the Pleiades, Arcturus, and Orion are some of\nthe names used by Him who \"calleth all the stars by their names,\nin the greatness of his power.\" Homer and Hesiod, 750 B.C., allude\nto a few stars and groups. The Arabians very early speak of the\nGreat Bear; but the Greeks completely nationalized the heavens.\nThey colonized the earth widely, but the heavens completely; and\nnightly over them marched the grand procession of their apotheosized\ndivinities. There Hercules perpetually wrought his mighty labors\nfor the good of man; there flashed and faded the changeful star\nAlgol, as an eye in the head of the snaky-haired Medusa; over them\nflew Pegasus, the winged horse of the poet, careering among the\nstars; there the ship Argo, which had explored all strange seas\nof earth, nightly sailed in the infinite realms of heaven; there\nPerseus perpetually killed the sea-monster by celestial aid, and\nperpetually won the chained Andromeda for his bride. Very evident\nwas their recognition of divine help: equally evident was [Page 196]\ntheir assertion of human ability and dominion. They gathered the\nillimitable stars, and put uncountable suns into the shape of the\nGreat Bear--the most colossal form of animal ferocity and\nstrength--across whose broad forehead imagination grows weary in\nflying; but they did not fail to put behind him a representative of\nthemselves, who forever drives him around a sky that never sets--a\nperpetual type that man's ambition and expectation correspond to\nthat which has always been revealed as the divine.\n\nThe heavens signify much higher power and wisdom to us; we retain the\nold pictures and groupings for the convenience of finding individual\nstars. It is enough for the astronomer that we speak of a star as\nsituated right ascension 13' 45\", declination 88\u00b0 40'. But for\nmost people, if not all, it is better to call it Polaris. So we\nmight speak of a lake in latitude 42\u00b0 40', longitude 79\u00b0 22', but\nit would be clearer to most persons to say Chatauqua. For exact\nlocation of a star, right ascension and declination must be given;\nbut for general indication its name or place in a constellation\nis sufficiently exact. The heaven is rather indeterminably laid\nout in irregular tracts, and the mythological names are preserved.\nThe brightest stars are then indicated in order by the letters of\nthe Greek alphabet--Alpha (a), Beta (b), Gamma (g), etc. After\nthese are exhausted, the Roman alphabet is used in the same manner,\nand then numbers are resorted to; so that the famous star 61 Cygni\nis the 111th star in brightness in that one constellation. An\nacquaintance with the names, peculiarities, and movements of the\nstars visible at different seasons of the year is an unceasing\nsource of pleasure. It [Page 197] is not vision alone that is\ngratified, for one fine enough may hear the morning stars sing\ntogether, and understand the speech that day uttereth unto day, and\nthe knowledge that night showeth unto night. One never can be alone\nif he is familiarly acquainted with the stars. He rises early in the\nsummer morning, that he may see his winter friends; in winter, that\nhe may gladden himself with a sight of the summer stars. He hails\ntheir successive rising as he does the coming of his personal\nfriends from beyond the sea. On the wide ocean he is commercing with\nthe skies, his rapt soul sitting in his eyes. Under the clear skies\nof the East he hears God's voice speaking to him, as to Abraham, and\nsaying, \"Look now toward the heavens, and tell the number of the\nstars, if thou be able to number them.\"\n\nA general acquaintance with the stars will be first attempted;\na more particular knowledge afterward. Fig. 67 (page 201) is a\nmap of the circumpolar region, which is in full view every clear\nnight. It revolves daily round Polaris, its central point. Toward\nthis star, the two end stars of the Great Dipper ever point, and\nare in consequence called \"the Pointers.\" The map may be held toward\nthe northern sky in such a position as the stars may happen to be.\nThe Great Bear, or Dipper, will be seen at nine o'clock in the\nevening above the pole in April and May; west of the pole, the\nPointers downward, in July and August; close to the north horizon\nin October and November; and east of the pole the Pointers highest,\nin January and February. The names of such constantly visible stars\nshould be familiar. In order, from the end of the tail of the Great\nBear, we have Benetnasch ae, Mizar z, Little Alcor close to it,\n[Page 198] Alioth, e Megrez, d at the junction, has been growing\ndimmer for a century, Phad, g Dubhe and Merak. It is best to get\nsome facility at estimating distances in degrees. Dubhe and Merak,\n\"the Pointers,\" are five degrees apart. Eighteen degrees forward of\nDubhe is the Bear's nose; and three pairs of stars, fifteen degrees\napart, show the position of the Bear's three feet. Follow \"the\nPointers\" twenty-nine degrees from Dubhe, and we come to the\npole-star. This star is double, made of two suns, both appearing as\none to the naked eye. It is a test of an excellent three-inch\ntelescope to resolve it into two. Three stars beside it make the\ncurved-up handle of the Little Dipper of Ursa Minor. Between the two\nBears, thirteen degrees from Megrez, and eleven degrees from Mizar,\nare two stars in the tail of the Dragon, which curves about to\nappropriate all the stars not otherwise assigned. Follow a curve of\nfifteen stars, doubling back to a quadrangle from five to three\ndegrees on a side, and thirty-five degrees from the pole, for his\nhead. His tongue runs out to a star four degrees in front. We shall\nfind, hereafter, that the foot of Hercules stands on this head. This\nis the Dragon slain by Cadmus, and whose teeth produced such a crop\nof sanguinary men.\n\nThe star Thuban was once the pole-star. In the year B.C. 2300 it\nwas ten times nearer the pole than Polaris is now. In the year\nA.D. 2100 the pole will be within 30' of Polaris; in A.D. 7500,\nit will be at a of Cepheus; in A.D. 13,500, within 7\u00b0 of Vega; in\nA.D. 15,700, at the star in the tongue of Draco; in A.D. 23,000,\nat Thuban; in A.D. 28,000, back to Polaris. This indicates no change\nin the position of the dome [Page 199] of stars, but a change in the\ndirection of the axis of the earth pointing to these various places\nas the cycles pass. As the earth goes round its orbit, the axis,\nmaintaining nearly the same direction, really points to every part\nof a circle near the north star as large as the earth's orbit, that\nis, 185,000,000 miles in diameter. But, as already shown, that\ncircle is too small to be discernible at our distance. The wide\ncircle of the pole through the ages is really made up of the\ninterlaced curves of the annual curves continued through 25,870\nyears. The stem of the spinning top wavers, describes a circle, and\nfinally falls; the axis of the spinning earth wavers, describes a\ncircle of nearly 28,000 years, and never falls.\n\nThe star g Draconis, also called Etanin, is famous in modern astronomy,\nbecause observations on this star led to the discovery of the\n_aberration of light_. If we held a glass tube perpendicularly out\nof the window of a car at rest, when the rain was falling straight\ndown, we could see the drops pass directly through. Put the car\nin motion, and the drops would seem to start toward us, and the\ntop of the tube must be bent forward, or the drops entering would\nstrike on the backside of the tube carried toward them. So our\ntelescopes are bent forward on the moving earth, to enable the\nentered light to reach the eye-piece. Hence the star does not appear\njust where it is. As the earth moves faster in some parts of its\norbit than others, this aberration is sometimes greater than at\nothers. It is fortunate that light moves with a uniform velocity,\nor this difficult, problem would be still further complicated.\nThe displacement of a star from this course is about 20\".43.\n\n[Page 200]\nOn the side of Polaris, opposite to Ursa Major, is King Cepheus,\nmade of a few dim stars in the form of the letter K. Near by is\nhis brilliant wife Cassiopeia, sitting on her throne of state.\nThey were the graceless parents who chained their daughter to a\nrock for the sea-monster to devour; but Perseus, swift with the\nwinged sandals of Mercury, terrible with his avenging sword, and\ninvincible with the severed head of Medusa, whose horrid aspect of\nsnaky hair and scaly body turned to stone every beholder, rescues\nthe maiden from chains, and leads her away by the bands of love.\nNothing could be more poetical than the life of Perseus. When he\nwent to destroy the dreadful Gorgon, Medusa, Pluto lent him his\nhelmet, which would make him invisible at will; Minerva loaned\nher buckler, impenetrable, and polished like a mirror; Mercury\ngave him a dagger of diamonds, and his winged sandals, which would\ncarry him through the air. Coming to the loathsome thing, he would\nnot look upon her, lest he, too, be turned to stone; but, guided\nby the reflection in the buckler, smote off her head, carried it\nhigh over Libya, the dropping blood turning to serpents, which\nhave infested those deserts ever since.\n\n[Illustration: Fig. 67.--Circumpolar Constellations. Always visible.\nIn this position.--January 20th, at 10 o'clock; February 4th, at\n9 o'clock; and February 19th, at 8 o'clock.]\n\nThe human mind has always been ready to deify and throne in the\nskies the heroes that labor for others. Both Perseus and Hercules\nare divine by one parent, and human by the other. They go up and\ndown the earth, giving deliverance to captives, and breaking every\nyoke. They also seek to purge away all evil; they slay dragons,\ngorgons, devouring monsters, cleanse the foul places of earth,\nand one of them so wrestles with death as to win a victim from his\ngrasp. Finally, by [Page 201] an ascension in light, they go up to\nbe in light forever. They are not ideally perfect. They right wrong\nby slaying wrong-doers, rather than by being crucified themselves;\nthey are just murderers; but that only plucks the fruit from the\ntree of evil. They never attempted to infuse a holy life. They\npunished rather than regenerated. It must be confessed, also, that\nthey were not sinless. But they were the best saviors the race could\nimagine, and are examples of that perpetual effort of the human mind\nto incarnate a Divine Helper who shall labor and die for the good of\nmen.\n\n[Page 202]\n[Illustration: Fig. 68.--Algol is on the Meridian, 51\u00b0 South of\nPole.--At 10 o'clock, December 7th; 9 o'clock, December 22d; 8\no'clock, January 5th.]\n\n_Equatorial Constellations._\n\nIf we turn our backs on Polaris on the 10th of November, at 10\no'clock in the evening, and look directly overhead, we shall see\nthe beautiful constellation of Andromeda. Together with the square\nof Pegasus, it makes another enormous dipper. The star a Alpheratz\nis in her face, the three at the left cross her breast. b and the\ntwo above mark the girdle of her loins, and g is in the foot. Perseus\nis near enough for help; and Cetus, the sea-monster, is far enough\naway to do no harm. Below, and east of Andromeda, is the Ram of\nthe golden fleece, recognizable by the three stars in an acute\ntriangle. The brightest is called Arietis, or Hamel. East of this\nare the Pleiades, and the V-shaped Hyades in Taurus, or the Bull.\nThe Pleiades rise about 9 o'clock on the evening of the 10th of\nSeptember, and at 3 o'clock A.M. on June 10th.\n\n[Page 203]\n[Illustration: Fig. 69.--Capella (45\u00b0 from the Pole) and Rigel\n(100\u00b0) are on the Meridian at 8 o'clock February 7th, 9 o'clock\nJanuary 22d, and at 10 o'clock January 7th.]\n\nFig. 69 extends east and south of our last map. It is the most\ngorgeous section of our heavens. (See the Notes to the Frontispiece.)\nNote the triangle, 26\u00b0 on a side, made by Betelguese, Sirius, and\nProcyon. A line from Procyon to Pollux leads quite near to Polaris.\nOrion is the mighty hunter. Under his feet is a hare, behind him\nare two dogs, and before him is the rushing bull. The curve of\nstars to the right of Bellatrix, g, represents his shield of the\nNemean lion's hide. The three stars of his belt make a measure\n3\u00b0 long; the upper one, Mintaker, is less than 30' south of the\nequinoctial. The ecliptic passes between Aldebaran and the Pleiades.\nSirius rises about 9 o'clock P.M. on the 1st of December, and about\n4 o'clock A.M. on the 16th of August. Procyon rises about half an\nhour earlier.\n\n[Page 204]\n[Illustration: Fig. 70--Regulus comes on the Meridian, 79\u00b0 south\nfrom the Pole, at 10 o'clock March 23d, 9 o'clock April 8th, and\nat 8 o'clock April 23d.]\n\nFig. 70 continues eastward. Note the sickle in the head and neck\nof the Lion. The star b is Denebola, in his tail. Arcturus appears\nby the word Bootes, at the edge of the map. These two stars make\na triangle with Spica, about 35\u00b0 on a side. The geometric head of\nHydra is easily discernible east of Procyon: The star g in the\nVirgin is double, with a period of 145 years. z is just above the\nequinoctial. There is a fine nebula two-thirds of the way from d to\nae, and a little above the line connecting the two. Coma Berenices\nis a beautiful cluster of faint stars. Spica rises at 9 o'clock on\nthe 10th of February, at 5 o'clock A.M. on the 6th of November.\n\n[Page 205]\n[Illustration: Fig. 7l.--Arcturus comes to the Meridian, 70\u00b0 from\nthe Pole, at 10 o'clock May 25th, 9 o'clock June 9th, and at 8\no'clock June 25th.]\n\nFig. 71 represents the sky to the eastward and northward of the\nlast. A line drawn from Polaris and Benetnasch comes east of Arcturus\nto the little triangle called his sons. Bootes drives the Great\nBear round the pole. Arcturus and Denebola make a triangle with\na, also called Cor Coroli, in the Hunting Dogs. This triangle, and\nthe one having the same base, with Spica for its apex, is called\nthe \"Diamond of the Virgin.\" Hercules appears head down--a in the\nface, b, g, d; in his shoulders, p; and ae; in the loins, t in the\nknee, the foot being bent to the stars at the right. The Serpent's\nhead, making an X, is just at the right of the g of Hercules, and\nthe partial circle of the Northern Crown above. The head of Draco\nis seen at b on the left of the map. Arcturus rises at 9 o'clock\nabout the 20th of February, and at 5 A.M. on the 22d of October;\nRegulus 3h. 35m. Earlier.\n\n[Page 206]\n[Illustration: Fig. 72.--Altair comes to the Meridian, 82\u00b0 from\nthe Pole, at 10 o'clock P.M. August 18th, at 9 o'clock September\n2d, and at 8 o'clock September 18th.]\n\nFig. 72 portrays the stars eastward and southward. Scorpio is one\nof the most brilliant and easily traced constellations. Antares, a,\nin the heart, is double. In Sagittarius is the Little Milk-dipper,\nand west of it the bended bow. Vega is at the top of the map. Near\nit observe z, a double, and e, a quadruple star. The point to which\nthe solar system is tending is marked by the sign of the earth\nbelow p; Herculis. The Serpent, west of Hercules, and coiled round\nnearly to Aquila, is very traceable. In the right-hand lower corner\nis the Centaur. Below, and always out of our sight, is the famous\na Centauri. The diamond form of the Dolphin is sometimes called\n\"Job's Coffin.\" The ecliptic passes close [Page 207] to b of\nScorpio, which star is in the head. Antares, in Scorpio, rises at 9\no'clock P.M. on May 9th, and at 5 o'clock A.M. on January 5th.\n\n[Illustration: Fig. 73.--Fomalhaut comes to the Meridian, only 17\u00b0\nfrom the horizon, at 8 o'clock November 4th.]\n\nIn Fig. 73 we recognize the familiar stars of Pegasus, which tell\nus we have gone quite round the heavens. Note the beautiful cross\nin the Swan. b in the bill is named Albireo, and is a beautiful\ndouble to almost any glass. Its yellow and blue colors are very\ndistinct. The place of the famous double star 61 Cygni is seen. The\nfirst magnitude star in the lower left-hand corner is Fomalhaut, in\nthe Southern Fish. a Pegasi is in the diagonal corner from Alpharetz,\nin Andromeda. The star below Altair is b Aquil\u00e6, and is called\nAlschain; the one above is g Aquil\u00e6, named Tarazed. This is not\na brilliant section of the sky. Altair rises at 9 o'clock on the\n29th of May, and at 6 o'clock A.M. on the 11th of January.\n\n[Page 208]\n[Illustration: Fig. 74.--Southern Circumpolar Constellations invisible\nnorth of the Equator.]\n\nFig. 74 gives the stars that are never seen by persons north of\nthe earth's equator. In the Ship is brilliant Canopus, and the\nremarkable variable ae. Below it is the beautiful Southern Cross,\nnear the pole of the southern heavens. Just below are the two first\nmagnitude stars Bungala, a, and Achernar, b, of the Centaur. Such\na number of unusually brilliant stars give the southern sky an\nunequalled splendor. In the midst of them, as if for contrast,\nis the dark hole, called by the sailors the \"Coal-sack,\" where\neven the telescope reveals no sign of light. Here, also, are the\ntwo Magellanic clouds, both easily discernible by the naked eye;\nthe larger two hundred times the apparent size of the moon, lying\nbetween the pole and Canopus, and the other between Achernar and\nthe pole. The smaller cloud is only one-fourth the size of the\nother. Both are mostly resolvable into groups of stars from the\nfifth to the fifteenth magnitude.\n\n[Page 209]\nFor easy out-door finding of the stars above the horizon at any\ntime, see star-maps at end of the book.\n\n_Characteristics of the Stars._\n\nSuch a superficial examination of stars as we have made scarcely\ntouches the subject. It is as the study of the baptismal register,\nwhere the names were anciently recorded, without any knowledge\nof individuals. The heavens signify much more to us than to the\nGreeks. We revolve under a dome that investigation has infinitely\nenlarged from their estimate. Their little lights were turned by\nclumsy machinery, held together by material connections. Our vast\nworlds are connected by a force so fine that it seems to pass out\nof the realm of the material into that of the spiritual. Animal\nferocity or a human Hercules could image their idea of power. Ours\nfinds no symbol, but rises to the Almighty. Their heavens were full\nof fighting Orions, wild bulls, chained Andromedas, and devouring\nmonsters. Our heavens are significant of harmony and unity; all\nworlds carried by one force, and all harmonized into perfect music.\nAll their voices blend their various significations into a personal\nspeaking, which says, \"Hast thou not heard that the everlasting\nGod, the Lord, the creator of the ends of the earth, fainteth not,\nneither is weary?\" There is no searching of his understanding.\nLift up your eyes on high, and behold who hath created all these\nthings, that brought out their host by number, that calleth them\nall by their names in the greatness of his power; for that he is\nstrong in power not one faileth.\n\n[Page 210]\n_Number._\n\nWe find about five thousand stars visible to the naked eye in the\nwhole heavens, both north and south. Of these twenty are of the\nfirst magnitude, sixty-five of the second, two hundred of the third,\nfour hundred of the fourth, eleven hundred of the fifth, and three\nthousand two hundred of the sixth. We think we can easily number\nthe stars; but train a six-inch telescope on a little section of the\nTwins, where six faint stars are visible, and over three thousand\nluminous points appear. The seventh magnitude has 13,000 stars;\nthe eighth, 40,000; the ninth, 142,000. There are 18,000,000 stars\nin the zone called the Milky Way. When our eyes are not sensitive\nenough to be affected by the light of far-off stars the tastimetre\nfeels their heat, and tells us the word of their Maker is true--\"they\nare innumerable.\"[*]\n\n[Footnote *: _Telescopic Work._--Look at the Hyades and Pleiades\nin Taurus. Notice the different colors of stars in them both. Find\nthe cluster Pr\u00e6sepe in Fig. 70, just a trifle above a point midway\nbetween Procyon and Regulus. It is equally distant from Procyon and\na point a little below Pollux. Sweep along the Milky Way almost\nanywhere, and observe the distribution of stars; in some places\nperfect crowds, in others more sparsely scattered. Find with the\nnaked eye the rich cluster in Perseus. Draw a line from Algol to\na of Perseus (Fig. 67); turn at right angles to the right, at a\ndistance of once and four-tenths the first line a brightness will\nbe seen. The telescope reveals a gorgeous cluster.]\n\n_Double and Multiple Stars._\n\nIf we look up during the summer months nearly overhead at the star\ne Lyra, east of Vega (Fig. 72), we shall see with the naked eye\nthat the star appears a little [Page 211] elongated. Turn your\nopera-glass upon it, and two stars appear. Turn a larger telescope\non this double star, and each of the components separate into two.\nIt is a double double star. We know that if two stars are near in\nreality, and not simply apparently so by being in the same line of\nsight, they must revolve around a common centre of gravity, or rush\nto a common ruin. Eagerly we watch to see if they revolve. A few\nyears suffice to show them in actual revolution. Nay, the movement\nof revolution has been decided before the companion star was\ndiscovered. Sirius has long been known to have a proper motion, such\nas it would have if another sun were revolving about it. Even the\ndirection of the unseen body could always be indicated. In February,\n1862, Alvan Clark, artist, poet, and maker of telescopes (which\nrequires even greater genius than to be both poet and artist),\ndiscovered the companion of Sirius just in its predicted place. As a\nmatter of fact, one of Mr. Clark's sons saw it first; but their fame\nis one. The time of revolution of this pair is fifty years. But one\ncompanion does not meet the conditions of the movements. Here must\nalso be one or more planets too small or dark to be seen. The double\nstar x in the Great Bear (see Fig. 70) makes a revolution in\nfifty-eight years.\n\nProcyon moves in an orbit which requires the presence of a companion\nstar, but it has as yet eluded our search. Castor is a double star;\nbut a third star or planet, as yet undiscovered, is required to\naccount for its perturbations. Men who discovered Neptune by the\nperturbations of Uranus are capable of judging the cause of the\nperturbations of suns. We have spoken of [Page 212] the whole orbit\nof the earth being invisible from the stars. The nearest star in our\nnorthern hemisphere, 61 Cygni, is a telescopic double star; the\nconstituent parts of it are forty-five times as far from each other\nas the earth is from the sun, yet it takes a large telescope to show\nany distance between the stars.[*]\n\n[Footnote *: _Telescopic Work._--Only such work will be laid out\nhere as can be done by small telescopes of from two to four inch\nobject-glasses. The numbers in Fig. 75 correspond to those of the\ntable.\n\n --------------------------------------------------------------------\n|   |            |             |Dist. of|Magni-|                     |\n|No.|     Name.  |     Fig.    | Parts. |tudes.|       Remarks.      |\n|---|------------|-------------|--------|------|---------------------|\n| 1.| e Lyr\u00e6     |      72     | 1' 56\" |      |Quadruple.           |\n| 2.| z Lyr\u00e6     |      72     |    44  |5 & 6 |Topaz and green.     |\n| 3.| b Cygni    |      73     |  34-1/2|3 & 6 |Yellow and blue.     |\n| 4.| 61 Cygni   |      73     |    20  |5 & 6 |Nearest star but one.|\n| 5.| Mizar      |      67     |    14  |3 & 4 |Both white.          |\n| 6.| Polaris    |      67     |  18-1/2|2 & 9 |Test object of eye   |\n|   |            |             |        |      | and glass.          |\n| 7.| r Orionis  |Frontispiece.|     7  |5 & 8 |Yellow and blue.     |\n| 8.| b Orionis  |      \"      |     9  |1 & 8 | Rigel.              |\n| 9.| d    \"     |      \"      |    10  |2 & 8 | Red and white.      |\n|10.| th   \"     |      \"      |        |      |Septuple.            |\n|11.| l    \"     |      \"      |     5  |      |White and violet.    |\n|12.| s    \"     |      \" A, B.|    11  |4 & 10|Octuple.             |\n|13.| Castor     |      69     |   5-1/2|2 & 3 |White.               |\n|14.| Pollux     |      69     |        |Triple|Orange, gray, lilac. |\n|15.| g Virginis |      70     |     5  |3 & 3 |Both yellow.         |\n --------------------------------------------------------------------\n]\n\nWhen g Virginis was observed in 1718 by Bradley, the component\nparts were 7\" asunder. He incidentally remarked in his note-book\nthat the line of their connection was parallel to the line of the\ntwo stars Spica, or a and d Virginis. By 1840 they were not more\nthan 1\" apart, and the line of their connection greatly changed.\nThe appearance of the star is given in Fig. 75 (15), commencing\nat the left, for the years 1837 '38 '39 '40 '45 '50 '60 and '79.\nalso a conjectural [Page 213] orbit, placed obliquely, and the\nposition of the stars at the times mentioned, commencing at the top.\nThe time of its complete revolution is one hundred and fifty years.\n\n[Illustration: Fig. 75.--Aspects and Revolution of Double Stars.]\n\nThe meaning of these double stars is that two or more suns revolve\nabout their centre of gravity, as the moon and earth about their\ncentre. If they have planets, as doubtless they have, the movement\nis no more complicated than the planets we call satellites of Saturn\nrevolving about their central body, and also about the sun. Kindle\nSaturn and Jupiter to a blaze, or let out their possible light, and\nour system would appear a triple star in the distance. Doubtless,\nin the far past, before these giant planets were cooled, it so\nappeared.\n\nWe find some stars double, others triple, quadruple, octuple, and\nmultiple. It is an extension of the same principles that govern\nour system. Some of these suns are so far asunder that they can\nswing their Neptunes between them, with less perturbation than\nUranus and Neptune have in ours. Light all our planets, and there\nwould be a multiple star with more or less suns seen,\n[Page 214]\naccording to the power of the instrument. Perhaps the octuple star\ns in Orion differs in no respect from our system, except in the\nsize and distance of its separate bodies, and less cooling, either\nfrom being younger, or from the larger bodies cooling more slowly.\nSuns are of all ages. Infinite variety fills the sky. It is as\npreposterous to expect that every system or world should have analogous\ncircumstances to ours at the present time, as to insist that every\nmember of a family should be of the same age, and in the same state\nof development. There are worlds that have not yet reached the\nconditions of habitability by men, and worlds that have passed\nthese conditions long since. Let them go. There are enough left,\nand an infinite number in the course of preparation. Some are fine\nand lasting enough to be eternal mansions.\n\n_Colored Stars._\n\nIn the cloudy morning we get only red light, but the sun is white.\nSo Aldebaran and Betelguese may be girt by vapors, that only the\nstrong red rays can pass. Again, an iron moderately heated gives\nout dull red light; becoming hotter, it emits white light. Sirius,\nRegulus, Vega, and Spica may be white from greater intensity of\nvibration. Procyon, Capella, and Polaris are yellow from less intensity\nof vibration. Again, burn salt in a white flame, and it turns to\nyellow; mix alcohol and boracic acid, ignite them, and a beautiful\ngreen flame results; alcohol and nitrate of strontia give red flame;\nalcohol and nitrate of barytes give yellow flame. So the composition\nof a sun, or the special development of anyone substance thereof\nat any time, may determine the color of a star.\n\n[Page 215]\nThe special glory of color in the stars is seen in the marked contrasts\npresented in the double and multiple stars. The larger star is\nusually white, still in the intensity of heat and vibration; the\nothers, smaller, are somewhat cooled off, and hence present colors\nlower down the scale of vibration, as green, yellow, orange, and\neven red.\n\nThat stars should change color is most natural. Many causes would\nproduce this effect. The ancients said Sirius was red. It is now\nwhite. The change that would most naturally follow mere age and\ncooling would be from white, through various colors, to red. We are\ncharmed with the variegated flowers of our gardens of earth, but\nhe who makes the fields blush with flowers under the warm kisses of\nthe sun has planted his wider gardens of space with colored stars.\n\"The rainbow flowers of the footstool, and the starry flowers of\nthe throne,\" proclaim one being as the author of them all.\n\n_Clusters of Stars._\n\nFrom double and multiple we naturally come to groups and clusters.\nAllusion has been made to the Hyades, Pleiades, etc. Everyone has\nnoticed the Milky Way. It seems like two irregular streams of compacted\nstars. It is not supposed that they are necessarily nearer together\nthan the stars in the sparse regions about the pole. But the 18,000,000\nsuns belonging to our system are arranged within a space represented\nby a flattened disk. If one hundred lights, three inches apart,\nare arranged on a hoop ten feet in diameter, they would be in a\ncircle. Add a thousand or two more the same distance apart, filling\nup the centre, and [Page 216] extending a few inches on each side of\nthe inner plane of the hoop: an eye in the centre, looking out\ntoward the edge, would see a milky way of lights; looking out toward\nthe sides or poles, would see comparatively few. It would seem as if\nthis oblate spheroidal arrangement was the result of a revolution of\nall the suns composing the system. Jupiter and earth are flattened\nat the poles for the same reason.\n\n[Illustration: Fig. 76.--Sprayed Cluster below ae in Hercules.]\n\n[Illustration: Fig. 77.--Globular Cluster.]\n\nIn various parts of the heavens there are small globular well-defined\nclusters, and clusters very irregular in form, marked with sprays\nof stars. There is a cluster of this latter class in Hercules,\njust under the S, in Fig. 72. \"Probably no one ever saw it with a\ngood telescope without a shout of wonder.\" Here is a cluster of the\nformer class represented in Fig. 77. \"The noble globular cluster,\no Centauri is beyond all comparison the richest and largest object\nof the kind in the heavens. Its stars are literally innumerable;\nand as their total light, when received by the naked eye, affects\nit hardly more than a star of the fifth to fourth\n[Page 217]\nmagnitude, the minuteness of each star may be imagined.\"\n\nThere are two possibilities of thought concerning these clusters.\nEither that they belong to our stellar system, and hence the stars\nmust be small and young, or they are another universe of millions\nof suns, so far way that the inconceivable distances between the\nstars are shrunken to a hand's-breadth, and their unbearable splendor\nof innumerable suns can only make a gray haze at the distance at\nwhich we behold them. The latter is the older and grander thought;\nthe former the newer and better substantiated.\n\n_Nebul\u00e6._\n\nThe gorgeous clusters we have been considering appear to the eye\nor the small telescope as little cloudlets of hazy light. One after\nanother were resolved into stars; and the natural conclusion was,\nthat all would yield and reveal themselves to be clustered suns,\nwhen we had telescopes of sufficient power. But the spectroscope,\nseeing not merely form but substance also, shows that some of them\nare not stars in any sense, but masses of glowing gas. Two of these\nnebul\u00e6 are visible to the naked eye: one in Andromeda (see Fig.\n68), and one around the middle star of the sword of Orion, shown\nin Fig.78. A three-inch telescope resolves th Orionis into the\nfamous trapezium, and a nine-inch instrument sees two stars more.\nThe shape of the nebula is changeable, and is hardly suggestive of\nthe moulding influence of gravitation. It is probably composed of\nglowing nitrogen and hydrogen gases. Nebul\u00e6 are of all conceivable\nshapes--circular, annular, oval, lenticular, [Page 218] conical,\nspiral, snake-like, looped, and nameless. Compare the sprays of the\nCrab nebul\u00e6 above z Tauri, seen in Fig. 79, and the ring nebula,\nFig. 80. This last possibly consists of stars, and is situated, as\nshown in Fig. 81, midway between b and g Lyr\u00e6.\n\n[Illustration: Fig. 78.--The great Nebula about the multiple Star\nth Orionis. (See Frontispiece.)]\n\nWhen Herschel was sweeping the heavens with his telescope, and\nsaw but few stars, he often said to his assistant, \"Prepare to\nwrite; the nebul\u00e6 are coming.\" They are most abundant where the\nstars are least so. A zone about the heavens 30\u00b0 wide, with the\nMilky Way in the centre, would include one-fourth of the celestial\nsphere; but instead of one-fourth, we find nine-tenths\n[Page 219]\nof the stars in this zone, and but one-tenth of the nebul\u00e6.\n\nThese immense masses of unorganized matter are noticed to change\ntheir forms, vary their light greatly, but not quickly; they change\nthrough the ages. \"God works slowly.\" He takes a thousand years\nto lift his hand off.\n\n[Illustration: Fig. 79.--Crab Nebula, near z Tauri. (See Frontispiece.)]\n\nThere are many unsolved problems connected with these strange bodies.\nWhether they belong to our system, or are beyond it, is not settled;\nthe weight of evidence leans to the first view.\n\n[Page 220]\n_Variable Stars._\n\n[Illustration: Fig. 80.--The Ring Nebula.]\n\nOur sun gives a variable amount of light, changing through a period\nof eleven years. Probably every star, if examined by methods\nsufficiently delicate and exact, would be found to be variable.\nThe variations of some [Page 221] stars are so marked as to\nchallenge investigation. b Lyr\u00e6 (Fig. 81) has two maxima and minima\nof light. In three days it rises from magnitude 4-1/2 to 3-1/2; in a\nweek falls to 4, and rises to 3-1/2; and in three days more drops to\n4-1/2: it makes all these changes in thirteen days; but this period\nis constantly increasing. The variations of one hundred and\nforty-three stars have been well ascertained.\n\n[Illustration: Fig. 81.--Constellation Lyra, showing place of the\nRing Nebula.]\n\nMira, or the Wonderful, in the Whale (Fig. 68), is easily found when\nvisible. Align from Capella to the Pleiades, and as much farther,\nand four stars will be seen, situated thus:\n\n    *\n  *  * *\n\nThe right-hand one is Mira. For half a month it shines as a star\nof the second magnitude. Then for three months it fades away, and\nlost to sight; going down even to the eleventh magnitude. But after\nfive months its resurrection morning mes; and in three months\nmore--eleven months in all--our Wonderful is in its full glory\nin the heavens. It its period and brilliancy are also variable.\nThe star Megrez, d in the Great Bear, has been growing dim [Page\n222] for a century. In 1836 Betelguese was exceedingly variable, and\ncontinued so till 1840, when the changes became much less\nconspicuous. Algol (Fig. 68) has been already referred to. This\nslowly winking eye is of the second magnitude during 2d. 14h. Then\nit dozes off toward sleep for 4h. 24m., when it is nearly invisible.\nIt wakes up during the same time; so that its period from maximum\nbrilliancy to the same state again is 2d. 20h. 48m. Its recognizable\nchanges are within five or six hours. As I write, March 25th, 1879,\nAlgol gives its minimum light at 9h. 36m. P.M. It passes fifteen\nminima in 43d. 13m. There will therefore be another minimum May 7th,\nat 9h. 49m. Its future periods are easy to estimate. Perhaps it has\nsome dark body revolving about it at frightful speed, in a period of\nless than three days. The period of its variability is growing\nshorter at an increasing rate. If its variability is caused by a\ndark body revolving about it, the orbit of that body is contracting,\nand the huge satellite will soon, as celestial periods are reckoned,\ncommence to graze the surface of the sun itself, rebound again and\nagain, and at length plunge itself into the central fire. Such an\nevent would evolve heat enough to make Algol flame up into a star of\nthe first magnitude, and perhaps out-blaze Sirius or Capella in our\nwinter sky.\n\nNone of the causes for these changes we have been able to conjecture\nseem very satisfactory. The stars may have opaque planets revolving\nabout them, shutting off their light; they may rotate, and have\nunequally illuminated sides; they may revolve in very elliptical\norbits, so as to greatly alter their distance from us; they may\nbe so situated in regard to zones of meteorites as [Page 223] to\ncall down periodically vast showers; but none or all of these\nsuppositions apply to all cases, if they do to any.\n\n_Temporary, New, and Lost Stars._\n\nBesides regular movements to right and left, up and down, to and\nfrom us--changes in the intensity of illumination by changes of\ndistance--besides variations occurring at regular and ascertainable\nintervals, there are stars called _temporary_, shining awhile and\nthen disappearing; _new_, coming to a definite brightness, and so\nremaining; and _lost_, those whose first appearance was not observed,\nbut which have utterly disappeared.\n\nIn November, 1572, a new star blazed out in Cassiopeia. Its place\nis shown in Fig. 67, ch g being the stars\n\n  d    *\n   g ch\n\nin the seat of the chair, and d being the first one in the back.\nThis star was visible at noonday, and was brighter than any other\nstar in the heavens. In January, 1573, it was less bright than\nJupiter; in April it was below the second magnitude, and the last\nof May it utterly disappeared. It was as variable in color as in\nbrilliancy. During its first two months, the period of greatest\nbrightness, it was dazzling white, then became yellow, and finally\nas red as Mars or Aldebaran, and so expired.\n\nA bright star was seen very near to the place of the _Pilgrim_,\nas the star of 1572 was called, in A.D. 945 and 1264. A star of\nthe tenth magnitude is now seen brightening slowly almost exactly\nin the same place. It is possible that this is a variable star\nof a period of about three hundred and ten years, and will blaze\nout again about 1885.\n\nBut we have had, within a few years, fine opportunities [Page 224]\nto study, with improved instruments, two new stars; On the evening\nof May 12th, 1866, a star of the second magnitude was observed in\nthe Northern Crown, where no star above the fifth magnitude had been\ntwenty-four hours before. In Argelander's chart a star of the tenth\nmagnitude occupies the place. May 13th it had declined to the third\nmagnitude, May 16th to the fourth, May 17th to the fifth, May 19th\nto the seventh, May 31st to the ninth, and has since diminished to\nthe tenth. The spectroscope showed it to be a star in the usual\ncondition; but through the usual colored spectrum, crossed with\nbright lines, shone four bright lines, two of which indicated\nglowing hydrogen. Here was plenty of proof that an unusual amount of\nthis gas had given this sun its sudden flame. As the hydrogen burned\nout the star grew dim.\n\nTwo theories immediately presented themselves: First, that vast\nvolumes had been liberated from within the orb by some sudden breaking\nup of the doors of its great deeps; or, second, this star had\nprecipitated upon itself, by attraction, some other sun or planet,\nthe force of whose impact had been changed into heat.\n\nThough we see the liberated hydrogen of our sun burst up with sudden\nflame, it can hardly be supposed that enough could be liberated\nat once to increase the light and heat one hundred-fold.\n\nIn regard to the second theory, it is capable of proof that two\nsuns half as large as ours, moving at a velocity of four hundred\nand seventy-six miles per second, would evolve heat enough to supply\nthe radiation of our sun for fifty million years. How could it be\npossible for a sun like this newly blazing orb to cool off to such a\n[Page 225] degree in a month? Besides, there would not be one chance\nin a thousand for two orbs to come directly together. They would\nrevolve about each other till a kind of grazing contact of grinding\nworlds would slowly kindle the ultimate heat.\n\nIt is far more likely that this star encountered an enormous stream\nof meteoric bodies, or perhaps absorbed a whole comet, that laid\nits million leagues of tail as fuel on the central fire. Only let\nit be remembered that the fuel is far more force than substance.\nAllusion has already been made to the sudden brightening of our\nsun on the first day of September, 1859. That was caused, no doubt,\nby the fall of large meteors, following in the train of the comet\nof 1843, or some other comet. What the effect would have been, had\nthe whole mass of the comet been absorbed, cannot be imagined.\n\nAnother new star lately appeared in Cygnus, near the famous star\n61--the first star in the northern hemisphere whose distance was\ndetermined. It was first seen November 24th, 1876, as a third magnitude\nstar of a yellow color. By December 2d it had sunk to the fourth\nmagnitude, and changed to a greenish color. It had then three bright\nhydrogen lines, the strong double sodium line, and others, which\nmade, it strongly resemble the spectrum of the chromosphere of our\nsun. An entirely different result appeared in the fading of these\ntwo stars. In the case of the star in the Crown, the extraordinary\nlight was the first to fade, leaving the usual stellar spectrum. In\nthe case of the star in Cygnus, the part of the spectrum belonging\nto stellar light was the first to fade, leaving the bright lines;\nthat is, the gas of one gave way to regular starlight, and the\nstarlight [Page 226] of the other having faded, the regular light of\nthe glowing gas continued. By some strange oversight, no one studied\nthe star again for six months. In September and November, 1877, the\nlight of this star was found to be blue, and not to be starlight at\nall. It had no rainbow spectrum, only one kind of rays, and hence\nonly one color. Its sole spectroscopic line is believed to be that\nof glowing nitrogen gas. We have then, probably, in the star of\n1876, a body shining by a feeble and undiscernible light, surrounded\nby a discernible immensity of light of nitrogen gas. This is its\nusual condition; but if a flight of meteors should raise the heat of\nthe central body so as to outshine the nebulous envelope, we should\nhave the conditions we discovered in November, 1876. But a rapid\ncooling dissipates the observable light of all colors, and leaves\nonly the glowing gas of one color.\n\n_Movements of Stars._\n\nWe call the stars _fixed_, but motion and life are necessary to all\nthings. Besides the motion in the line of sight described already,\nthere is motion in every other conceivable direction. We knew Sirius\nmoved before we had found the cause. We know that our sun moves\nback and forth in his easy bed one-half his vast diameter, as the\nlarger planets combine their influence on one side or the other.\n\nThe sun has another movement. We find the stars in Hercules gradually\nspreading from each other. Hercules's brawny limbs grow brawnier\nevery century. There can be but one cause: we are approaching that\nquarter of the heavens. (See [Symbol], Fig. 72.) We are even [Page\n227] able to compute the velocity of our approach; it is four miles\na second. The stars in the opposite quarter of the heavens in Argo\nare drawing nearer together.\n\nThis movement would have no effect on the apparent place of the\nstars at either pole, if they were all equally distant; but it\nmust greatly extend or contract the apparent space between them,\nsince they are situated at various distances.\n\nIndependent of this, the stars themselves are all in motion, but so\nvast is the distance from which we observe them that it has taken\nan accumulation of centuries before they could be made measurable.\nA train going forty miles an hour, seen from a distance of two\nmiles, almost seems to stand still. Arcturus moves through space\nthree times as fast as the earth, but it takes a century to appear\nto move the eighth part of the diameter of the moon. There is a\nstar in the Hunting Dogs, known as 1830 Groombridge, which has a\nvelocity beyond what all the attraction of the matter of the known\nuniverse could give it. By the year 9000 it may be in Berenice's\nHair.\n\nSome stars have a common movement, being evidently related together.\nA large proportion of the brighter stars between Aldebaran and\nthe Pleiades have a common motion eastward of about ten seconds\na century. All the angles marked by a, b, g, ch Orionis will be\naltered in different directions; l is moving toward g. l and e\nwill appear as a double star. In A.D. 50,000 Procyon will be nearer\nch Orionis than Rigel now is, and Sirius will be in line with a and\nch Orionis. All the stars of the Great Dipper, except Benetnasch\nand Dubhe, have a common motion somewhat in the direction [Page 228]\nof Thuban (Fig. 67), while the two named have a motion nearly\nopposite. In 36,000 years the end of the Dipper will have fallen out\nso that it will hold no water, and the handle will be broken square\noff at Mizar. \"The Southern Cross,\" says Humboldt, \"will not always\nkeep its characteristic form, for its four stars travel in different\ndirections with unequal velocities. At the present time it is not\nknown how many myriads of years must elapse before its entire\ndislocation.\"\n\nThese movements are not in fortuitous or chaotic ways, but are\ndoubtless in accordance with some perfect plan. We have climbed\nup from revolving earth and moon to revolving planets and sun,\nin order to understand how two or ten suns can revolve about a\ncommon centre. Let us now leap to the grander idea that all the\ninnumerable stars of a winter night not only loan, but must revolve\nabout some centre of gravity. Men have been looking for a central\nsun of suns, and have not found it. None is needed. Two suns can\nbalance about a point; all suns can swing about a common centre.\nThat one unmoving centre may be that city more gorgeous than Eastern\nimagination ever conceived, whose pavement is transparent gold,\nwhose walls are precious stones, whose light is life, and where\nno dark planetary bodies ever cast shadows. There reigns the King\nand Lord of all, and ranged about are the far-off provinces of his\nmaterial systems. They all move in his sight, and receive power\nfrom a mind that never wearies.\n\n\n\n\n[Page 229]\nXI.\n\nTHE WORLDS AND THE WORD.\n\n\"The worlds were framed by the word of God.\"--_Heb._ xi., 3.\n\n[Page 230]\n  \"Mysterious night! when our first parent knew thee\n  From report divine, and heard thy name,\n  Did he not tremble for this lovely frame,\n  This glorious canopy of light and blue?\n  Yet, 'neath a curtain of translucent dew,\n  Bathed in the rays of the great setting flame,\n  Hesperus, with all the host of heaven, came,\n  And lo! creation widened in man's view.\n  Who could have thought such darkness lay concealed\n  Within thy beams, O Sun! Oh who could find,\n  Whilst fruit and leaf and insect stood revealed,\n  That to such countless worlds thou mad'st us blind!\n  Why do we then shun death with anxious strife?\n  If light conceal so much, wherefore not life?\"\n    BLANCO WHITE.\n\n\n\n\n[Page 231]\nXI.\n\n_THE WORLDS AND THE WORD._\n\nMen have found the various worlds to be far richer than they originally\nthought. They have opened door after door in their vast treasuries,\nhave ascended throne after throne of power, and ruled realms of\nincreasing extent. We have no doubt that unfoldings in the future\nwill amaze even those whose expectations have been quickened by\nthe revealings of the past. What if it be found that the Word is\nequally inexhaustible?\n\nAfter ages of thought and discovery we have come out of the darkness\nand misconceptions of men. We believe in no serpent, turtle, or\nelephant supporting the world; no Atlas holding up the heavens;\nno crystal domes, \"with cycles and epicycles scribbled o'er.\" What\nif it be found that one book, written by ignorant men, never fell\ninto these mistakes of the wisest! Nay, more, what if some of the\ngreatest triumphs of modern science are to be found plainly stated\nin a book older than the writings of Homer? If suns, planets, and\nsatellites, with all their possibilities of life, changes of flora\nand fauna, could be all provided for, as some scientists tell us,\nin the fiery star-dust of a cloud, why may not the same Author\nprovide a perpetually widening river of life in his Word? As we\nbelieve He is perpetually present in his worlds, we know He has\n[Page 232] promised to be perpetually present in his Word, making it\nalive with spirit and life.\n\nThe wise men of the past could not avoid alluding to ideas the falsity\nof which subsequent discovery has revealed; but the writers of the\nBible did avoid such erroneous allusion. Of course they referred\nto some things, as sunrise and sunset, according to appearance;\nbut our most scientific books do the same to-day. That the Bible\ncould avoid teaching the opposite of scientific truth proclaims\nthat a higher than human wisdom was in its teaching.\n\nThat negative argument is strong, but the affirmative argument is\nmuch stronger. The Bible declares scientific truth far in advance\nof its discovery, far in advance of man's ability to understand\nits plain declarations. Take a few conspicuous illustrations:\n\nThe Bible asserted from the first that the present order of things\nhad a beginning. After ages of investigation, after researches in\nthe realms of physics, arguments in metaphysics, and conclusions\nby the necessities of resistless logic, science has reached the\nsame result.\n\nThe Bible asserted from the first that creation of matter preceded\narrangement. It was chaos--void--without form--darkness; arrangement\nwas a subsequent work. The world was not created in the form it\nwas to have; it was to be moulded, shaped, stratified, coaled,\nmountained, valleyed, subsequently. All of which science utters\nages afterward.\n\nThe Bible did not hesitate to affirm that light existed before\nthe sun, though men did not believe it, and used it as a weapon\nagainst inspiration. Now we praise men for having demonstrated\nthe oldest record.\n\n[Page 233]\nIt is a recently discovered truth of science that the trata of\nthe earth were formed by the action of water, and the mountains\nwere once under the ocean. It is an idea long familiar to Bible\nreaders: \"Thou coverest the earth with the deep as with a garment.\nThe waters stood above the mountains. At thy rebuke they fled; at\nthe voice of thy thunder they hasted away. The mountains ascend;\nthe valleys descend into the place thou hast founded for them.\"\nHere is a whole volume of geology in a paragraph. The thunder of\ncontinental convulsions is God's voice; the mountains rise by God's\npower; the waters haste away unto the place God prepared for them.\nOur slowness of geological discovery is perfectly accounted for by\nPeter. \"For of this they are _willingly ignorant_, that by the word\nof God there were heavens of old, and land framed out of water, and\nby means of water, whereby the world that then was, being overflowed\nby water, perished.\" We recognize these geological subsidences,\nbut we read them from the testimony of the rocks more willingly\nthan from the testimony of the Word.\n\nScience exults in having discovered what it is pleased to call an\norder of development on earth--tender grass, herb, tree; moving\ncreatures that have life in the waters; bird, reptile, beast, cattle,\nman. The Bible gives the same order ages before, and calls it God's\nsuccessive creations.\n\nDuring ages on ages man's wisdom held the earth to be flat. Meanwhile,\nGod was saying, century after century, of himself, \"He sitteth upon\nthe sphere of the earth\" (Gesenius).\n\nMen racked their feeble wits for expedients to uphold [Page 234] the\nearth, and the best they could devise were serpents, elephants, and\nturtles; beyond that no one had ever gone to see what supported\nthem. Meanwhile, God was perpetually telling men that he had hung\nthe earth upon nothing.\n\nMen were ever trying to number the stars. Hipparchus counted one\nthousand and twenty-two; Ptolemy one thousand and twenty-six; and\nit is easy to number those visible to the naked eye. But the Bible\nsaid, when there were no telescopes to make it known, that they\nwere as the sands of the sea, \"innumerable.\" Science has appliances\nof enumeration unknown to other ages, but the space-penetrating\ntelescopes and tastimeters reveal more worlds--eighteen millions\nin a single system, and systems beyond count--till men acknowledge\nthat the stars are innumerable to man. It is God's prerogative \"to\nnumber all the stars; he also calleth them all by their names.\"\n\nTorricelli's discovery that the air had weight was received with\nincredulity. For ages the air had propelled ships, thrust itself\nagainst the bodies of men, and overturned their works. But no man\never dreamed that weight was necessary to give momentum. During\nall the centuries it had stood in the Bible, waiting for man's\ncomprehension: \"He gave to the air its weight\" (Job xxviii. 25).\n\nThe pet science of to-day is meteorology. The fluctuations and\nvariations of the weather have hitherto baffled all attempts at\nunravelling them. It has seemed that there was no law in their\nfickle changes. But at length perseverance and skill have triumphed,\nand a single man in one place predicts the weather and winds [Page\n235] for a continent. But the Bible has always insisted that the\nwhole department was under law; nay, it laid down that law so\nclearly, that if men had been willing to learn from it they might\nhave reached this wisdom ages ago. The whole moral law is not more\nclearly crystallized in \"Thou shalt love the Lord thy God with all\nthy heart, and thy neighbor as thyself,\" than all the fundamentals\nof the science of meteorology are crystallized in these words: \"The\nwind goeth toward the south (equator), and turneth about (up) unto\nthe north; it whirleth about continually, and the wind returneth\nagain according to his circuits (established routes). All the rivers\nrun into the sea; yet the sea is not full: unto the place from\nwhence the rivers come, thither they return again\" (Eccles. i. 6,\n7).\n\nThose scientific queries which God propounded to Job were unanswerable\nthen; most of them are so now. \"Whereon are the sockets of the\nearth made to sink?\" Job never knew the earth turned in sockets;\nmuch less could he tell where they were fixed. God answered this\nquestion elsewhere. \"He stretcheth the north (one socket) over\nthe empty place, and hangeth the earth upon nothing.\" Speaking\nof the day-spring, God says the earth is _turned_ to it, as clay\nto the seal. The earth's axial revolution is clearly recognized.\nCopernicus declared it early; God earlier.\n\nNo man yet understands the balancing of the clouds, nor the suspension\nof the frozen masses of hail, any more than Job did.\n\nHad God asked if he had perceived the _length_ of the earth, many\na man to-day could have answered yes. But the eternal ice keeps\nus from perceiving the _breadth_ [Page 236] of the earth, and shows\nthe discriminating wisdom of the question.\n\nThe statement that the sun's going is from the end of the heaven,\nand his circuit to the ends of it, has given edge to many a sneer\nat its supposed assertion that the sun went round the earth. It\nteaches a higher truth--that the sun itself obeys the law it enforces\non the planets, and flies in an orbit of its own, from one end of\nheaven in Argo to the other in Hercules.\n\nSo eminent an astronomer and so true a Christian as General Mitchell,\nwho understood the voices in which the heavens declare the glory of\nGod, who read with delight the Word of God em bodied in worlds, and\nwho fed upon the written Word of God as his daily bread, declared,\n\"We find an aptness and propriety in all these astronomical\nillustrations, which are not weakened, but amazingly strengthened,\nwhen viewed in the clear light of our present knowledge.\" Herschel\nsays, \"All human discoveries seem to be made only for the purpose\nof confirming more strongly the truths that come from on high, and\nare contained in the sacred writings.\" The common authorship of\nthe worlds and the Word becomes apparent; their common unexplorable\nwealth is a necessary conclusion.\n\nSince the opening revelations of the past show an unsearchable\nwisdom in the Word, has that Word any prophecy concerning mysteries\nnot yet understood, and events yet in the future? There are certain\nproblems as yet insolvable. We have grasped many clews, and followed\nthem far into labyrinths of darkness, but not yet through into\nlight.\n\nWe ask in vain, \"What is matter?\" No man can [Page 237] answer. We\ntrace it up through the worlds, till its increasing fineness, its\ngrowing power, and possible identity of substance, seem as if the\nnext step would reveal its spirit origin. What we but hesitatingly\nstammer, the Word boldly asserts.\n\nWe ask, \"What is force?\" No man can answer. We recognize its various\ngrades, each subordinate to the higher--cohesion dissolvable by\nheat; the affinity of oxygen and hydrogen in water overcome by\nthe piercing intensity of electric fire; rivers seeking the sea\nby gravitation carried back by the sun; rock turned to soil, soil\nto flowers; and all the forces in nature measurably subservient to\nmind. Hence we partly understand what the Word has always taught\nus, that all lower forces must be subject to that which is highest.\nHow easily can seas be divided, iron made to swim, water to burn,\nand a dead body to live again, if the highest force exert itself\nover forces made to be mastered. When we have followed force to\nits highest place, we always find ourselves considering the forces\nof mind and spirit, and say, in the words of the Scriptures, \"God\nis spirit.\"\n\nWe ask in vain what is the end of the present condition of things.\nWe have read the history of our globe with great difficulty--its\nprophecy is still more difficult. We have asked whether the stars\nform a system, and if so, whether that system is permanent. We\nare not able to answer yet. We have said that the sun would in\ntime become as icy cold and dead as the moon, and then the earth\nwould wander darkling in the voids of space. But the end of the\nearth, as prophesied in the Word, is different: \"The heavens will\npass away with [Page 238] a rushing noise, and the elements will be\ndissolved with burning heat, and the earth and the works therein\nwill be burned up.\" The latest conclusions of science point the same\nway. The great zones of uncondensed matter about the sun seem to\nconstitute a resisting medium as far as they reach. Encke's comet,\nwhose orbit comes near the sun, is delayed. This gives gravitation\nan overwhelming power, and hence the orbit is lessened and a\nrevolution accomplished more quickly. Faye's comet, which wheels\nbeyond the track of Mars, is not retarded. If the earth moves\nthrough a resisting substance, its ultimate fall into the sun is\ncertain. Whether in that far future the sun shall have cooled off,\nor will be still as hot as to-day, Peter's description would\nadmirably portray the result of the impact. Peters description,\nhowever, seems rather to indicate an interference of Divine power at\nan appropriate time before a running down of the system at present\nin existence, and a re-endowment of matter with new capabilities.\n\nAfter thousands of years, science discovered the true way to knowledge.\nIt is the Baconian way of experiment, of trial, of examining the\nactual, instead of imagining the ideal. It is the acceptance of the\nScriptural plan. \"If a man wills to do God's will, he shall know.\"\nOh taste and see! In science men try hypotheses, think the best they\ncan, plan broadly as possible, and then see if facts sustain the\ntheory. They have adopted the Scriptural idea of accepting a plan,\nand then working in faith, in order to acquire knowledge. Fortunately,\nin the work of salvation the plan is always perfect. But, in order\nto make the trial under the most favorable circumstances, there\nmust be faith. The faith of [Page 239] science is amazing; its\nassertions of the supersensual are astounding. It affirms a thousand\nthings that cannot be physically demonstrated: that the flight of a\nrifle-ball is parabolic; that the earth has poles; that gages are\nmade of particles; that there are atoms; that an electric light\ngives ten times as many rays as are visible; that there are sounds\nto which we are deaf, sights to which we are blind; that a thousand\nobjects and activities are about us, for the perception of which we\nneed a hundred senses instead of five. These faiths have nearly all\nled to sight; they have been rewarded, and the world's wealth of\nknowledge is the result. The Word has ever asserted the\nsupersensuous, solicited man's faith, and ever uplifted every true\nfaith into sight. Lowell is partly right when he sings:\n\n \"Science was Faith once; Faith were science now,\n  Would she but lay her bow and arrows by,\n  And aim her with the weapons of the time.\"\n\nFaith laid her bow and arrows by before men in pursuit of worldly\nknowledge discovered theirs.\n\nWhat becomes of the force of the sun that is being spent to-day?\nIt is one of the firmest rocks of science that there can be no\nabsolute destruction of force. It is all conserved somehow. But\nhow? The sun contracts, light results, and leaps swiftly into all\nencircling space. It can never be returned. Heat from stars invisible\nby the largest telescope enters the tastimeter, and declares that\nthat force has journeyed from its source through incalculable years.\nThere is no encircling dome to reflect all this force back upon\nits sources. Is it lost? Science, in defence of its own dogma,\nshould [Page 240] assign light a work as it flies in the space which\nwe have learned cannot be empty. There ought to be a realm where\nlight's inconceivable energy is utilized in building a grander\nuniverse, where there is no night. Christ said, as he went out of\nthe seen into the unseen, \"I go to prepare a place for you;\" and\nwhen John saw it in vision the sun had disappeared, the moon was\ngone, but the light still continued.\n\nScience finds matter to be capable of unknown refinement; water\nbecomes steam full of amazing capabilities: we add more heat, superheat\nthe steam, and it takes on new aptitudes and uncontrollable energy.\nZinc burned in acid becomes electricity, which enters iron as a kind\nof soul, to fill all that body with life. All matter is capable\nof transformation, if not transfiguration, till it shines by the\nlight of an indwelling spirit. Scripture readers know that bodies\nand even garments can be transfigured, be made astrapton (Luke xxiv.\n4), shining with an inner light. They also look for new heavens and\na new earth endowed with higher powers, fit for perfect beings.\n\nWhen God made matter, so far as our thought permits us to know,\nhe simply made force stationary and unconscious. Thereafter he\nmoves through it with his own will. He can at any time change these\nforces, making air solid, water and rock gaseous, a world a cloud,\nor a fire-mist a stone. He may at some time restore all force to\nconsciousness again, and make every part of the universe thrill\nwith responsive joy. \"Then shall the mountains and the hills break\nforth before you into singing, and all the trees of the field clap\ntheir hands.\" One of these changes is to come to the earth. [Page\n241] Amidst great noise the heaven shall flee, the earth be burned\nup, and all their forces be changed to new forms. Perhaps it will\nnot then be visible to mortal eyes. Perhaps force will then be made\nconscious, and the flowers thereafter return our love as much as\nlower creatures do now. A river and tree of life may be consciously\nalive, as well as give life. Poets that are nearest to God are\nconstantly hearing the sweet voices of responsive feeling in nature.\n\n              \"For his gayer hours\n  She has a voice of gladness and a smile,\n  And eloquence of beauty; and she glides\n  Into his darker musings with a mild\n  And gentle sympathy, that steals away\n  Their sharpness ere he is aware.\"\n\nProphets who utter God's voice of truth say, \"The wilderness and\nthe solitary place shall be glad for holy men, and the desert shall\nrejoice and blossom as the rose. It shall blossom abundantly and\nrejoice, even with joy and singing.\"\n\nDistinguish clearly between certainty and surmise. The certainty is\nthat the world will pass through catastrophic changes to a perfect\nworld. The grave of uniformitarianism is already covered with grass.\nHe that creates promises to complete. The invisible, imponderable,\ninaudible ether is beyond our apprehension; it transmits impressions\n186,000 miles a second; it is millions of times more capable and\nenergetic than air. What may be the bounds of its possibility none\ncan imagine, for law is not abrogated nor designs disregarded as\nwe ascend into higher realms. Law works out more beautiful designs\nwith more absolute certainty. Why [Page 242] should there not be a\nfiner universe than this, and disconnected from this world\naltogether--a fit home for immortal souls? It is a necessity.\n\nGod filleth all in all, is everywhere omnipotent and wise. Why\nshould there be great vacuities, barren of power and its creative\noutgoings? God has fixed the stars as proofs of his agency at some\npoints in space. But is it in points only? Science is proud of its\ndiscovery that what men once thought to be empty space is more\nintensely active than the coarser forms of matter can be. But in\nthe long times which are past Job glanced at earth, seas, clouds,\npillars of heaven, stars, day, night, all visible things, and then\nadded: \"Lo! these are only the outlying borders of his works. What\na whisper of a word we hear of _Him!_ The thunder of his power\nwho can comprehend?\"\n\nScience discovers that man is adapted for mastery in this world.\nHe is of the highest order of visible creatures. Neither is it\npossible to imagine an order of beings generically higher to be\nconnected with the conditions of the material world. This whole\nsecret was known to the author of the oldest writing. \"And God\nblessed them, and God said unto them: Be fruitful, and multiply,\nand replenish the earth, and subdue it: and have dominion over\nthe fish of the sea, and over the fowl of the air, and over every\nliving thing that moveth upon the earth.\" The idea is never lost\nsight of in the sacred writings. And while every man knows he must\nfail in one great contest, and yield himself to death, the later\nportions of the divine Word offer him victory even here. The typical\nman is commissioned to destroy even death, and make man a sharer\nin the victory. [Page 243] Science babbles at this great truth of\nman's position like a little child; Scripture treats it with a\nbreadth of perfect wisdom we are only beginning to grasp.\n\nScience tells us that each type is prophetic of a higher one. The\nwhale has bones prophetic of a human hand. Has man reached perfection?\nIs there no prophecy in him? Not in his body, perhaps; but how his\nwhole soul yearns for greater beauty. As soon as he has found food,\nthe savage begins to carve his paddle, and make himself gorgeous with\nfeathers. How man yearns for strength, subduing animal and cosmic\nforces to his will! How he fights against darkness and death, and\nstrives for perfection and holiness! These prophecies compel us to\nbelieve there is a world where powers like those of electricity and\nluminiferous ether are ever at hand; where its waters are rivers\nof life, and its trees full of perfect healing, and from which all\nunholiness is forever kept. What we infer, Scripture affirms.\n\nScience tells us there has been a survival of the fittest. Doubtless\nthis is so. So in the future there will be a survival of the fittest.\nWhat is it? Wisdom, gentleness, meekness, brotherly kindness, and\ncharity. Over those who have these traits death hath no permanent\npower. The caterpillar has no fear as he weaves his own shroud; for\nthere is life within fit to survive, and ere long it spreads its\ngorgeous wings, and flies in the air above where once it crawled. Man\nhas had two states of being already. One confined, dark, peculiarly\nnourished, slightly conscious; then he was born into another--wide,\ndifferently nourished, and intensely [Page 244] conscious. He knows\nhe may be born again into a life wider yet, differently nourished,\nand even yet more intensely conscious. Science has no hint how a\nlong ascending series of developments crowned by man may advance\nanother step, and make man isaggelos--equal to angels. But the\nsimplest teaching of Scripture points out a way so clear that a\nchild need not miss the glorious consummation.\n\nWhen Uranus hastened in one part of its orbit, and then retarded,\nand swung too wide, men said there must be another attracting world\nbeyond; and, looking there, Neptune was found. So, when individual\nmen are so strong that nations or armies cannot break down their\nwills; so brave, that lions have no terrors; so holy, that temptation\ncannot lure nor sin defile them; so grand in thought, that men\ncannot follow; so pure in walk, that God walks with them--let us\ninfer an attracting world, high and pure and strong as heaven. The\neleventh chapter of Hebrews is a roll-call of heroes of whom this\nworld was not worthy. They were tortured, not accepting deliverance,\nthat they might obtain a better resurrection. The world to come\ninfluenced, as it were, the orbits of their souls, and when their\nbodies fell off, earth having no hold on them, they sped on to\ntheir celestial home. The tendency of such souls necessitates such\na world.\n\nThe worlds and the Word speak but one language, teach but one set\nof truths. How was it possible that the writers of the earlier\nScriptures described physical phenomena with wonderful sublimity,\nand with such penetrative truth? They gazed upon the same heaven\nthat those men saw who ages afterward led the world in knowledge.\nThese latter were near-sighted, and absorbed [Page 245] in the\npictures on the first veil of matter; the former were far-sighted,\nand penetrated a hundred strata of thickest material, and saw the\nimmaterial power behind. The one class studied the present, and made\nthe gravest mistakes; the other pierced the uncounted ages of the\npast, and uttered the profoundest wisdom. There is but one\nexplanation. He that planned and made the worlds inspired the Word.\n\nScience and religion are not two separate departments, they are\nnot even two phases of the same truth. Science has a broader realm\nin the unseen than in the seen, in the source of power than in the\noutcomes of power, in the sublime laws of spirit than in the laws\nof matter; and religion sheds its beautiful light over all stages\nof life, till, whether we eat or whether we drink, or whatsoever\nwe do, we may do all for the glory of God. Science and religion\nmake common confession that the great object of life is to learn\nand to grow. Both will come to see the best possible means, for\nthe attainment of this end is a personal relation to a teacher\nwho is the Way, the Truth, and the Life.\n\n\n\n\n[Page 247]\nXII.\n\nTHE ULTIMATE FORCE.\n\n\"In the beginning was the Word, and the Word was with God, and the\nWord was God. The same was in the beginning with God. All things\nbecame by him, and without him was not anything made that was made\n* * * and by him all things stand together.\"\n\n[Page 248]\n \"O thou eternal one; whose presence blight\n  All space doth occupy--all motion guide--\n  Thou from primeval nothingness didst call\n  First chaos, then existence. Lord, on thee\n  Eternity had its foundation: all\n  Sprung forth from thee--of light, joy, harmony,\n  Sole origin: all life, all beauty thine.\n  Thy word created all, and doth create;\n  Thy splendor fills all space with rays divine;\n  Thou art and wert, and shalt be glorious, great;\n  Life-giving, life-sustaining Potentate,\n  Thy chains the unmeasured universe surround--\n  Upheld by thee, by thee inspired with breath.\"\n                                     DERZHAVIN.\n\n\n\n\n[Page 249]\nXII.\n\n_THE ULTIMATE FORCE._\n\nThe universe is God's name writ large. Thought goes up the shining\nsuns as golden stairs, and reads the consecutive syllables--all\nmight, and wisdom, and beauty; and if the heart be fine enough and\npure enough, it also reads everywhere the mystic name of love. Let\nus learn to read the hieroglyphics, and then turn to the blazonry\nof the infinite page. That is the key-note; the heavens and the earth\ndeclaring the glory of God, and men with souls attuned listening.\n\nTo what voices shall we listen first? Stand on the shore of a lake\nset like an azure gem among the bosses of green hills. The patter\nof rain means an annual fall of four cubic feet of water on every\nsquare foot of it. It weighs two hundred and forty pounds to the\ncubic foot, one hundred million tons on the surface of a little\nsheet of water twenty miles long by three wide. Now, all that weight\nof falling rain had to be lifted, a work compared to which taking\nup mountains and casting them into the sea is pastime. All that\nwater had to be taken up before it could be cast down, and carried\nhundreds of miles before it could be there. You have heard Niagara's\nthunder; have stood beneath the falling immensity; seen it ceaselessly\npoured from an infinite hand; felt that you would be ground to atoms\nif you fell into that resistless flood. Well, all that infinity of\n[Page 250] water had to be lifted by main force, had to be taken up\nout of the far Pacific, brought over the Rocky Mountains; and the\nMississippi keeps bearing its wide miles of water to the Gulf, and\nNiagara keeps thundering age after age, because there is power\nsomewhere to carry the immeasurable floods all the time the other\nway in the upper air.\n\nBut this is only the Alpha of power. Professor Clark, of Amherst,\nMassachusetts, found that such a soft and pulpy thing as a squash\nhad so great a power of growth that it lifted three thousand pounds,\nand held it day and night for months. It toiled and grew under the\ngrowing weight, compacting its substance like oak to do the work.\nAll over the earth this tremendous power and push of life goes\non--in the little star-eyed flowers that look up to God only on\nthe Alpine heights, in every tuft of grass, in every acre of wheat,\nin every mile of prairie, and in every lofty tree that wrestles\nwith the tempests of one hundred winters. But this is only the B\nin the alphabet of power.\n\nRise above the earth, and you find the worlds tossed like playthings,\nand hurled seventy times as fast as a rifle-ball, never an inch\nout of place or a second out of time. But this is only the C in\nthe alphabet of power.\n\nRise to the sun. It is a quenchless reservoir of high-class energy.\nOur tornadoes move sixty miles an hour, those of the sun twenty\nthousand miles an hour. A forest on fire sends its spires of flame\none hundred feet in air, the sun sends its spires of flame two\nhundred thousand miles. All our fires exhaust the fuel and burn\nout. If the sun were pure coal, it would burn out in five thousand\nyears; and yet this sea of unquenchable [Page 251] flame seethes and\nburns, and rolls and vivifies a dozen worlds, and flashes life along\nthe starry spaces for a million years without any apparent\ndiminution. It sends out its power to every planet, in the vast\ncircle in which it lies. It fills with light not merely a whole\ncircle, but a dome; not merely a dome above, but one below, and on\nevery side. At our distance of ninety-two and a half millions of\nmiles, the great earth feels that power in gravitation, tides,\nrains, winds, and all possible life--every part is full of power.\nFill the earth's orbit with a circle of such receptive\nworlds--seventy thousand instead of one--everyone would be as fully\nsupplied with power from this central source. More. Fill the whole\ndome, the entire extent of the surrounding sphere, bottom, sides,\ntop, a sphere one hundred and eighty-five million miles in diameter,\nand everyone of these uncountable worlds would be touched with the\nsame power as one; each would thrill with life. This is only the D\nof the alphabet of power. And glancing up to the other suns, one\nhundred, five hundred, twelve hundred times as large, double,\ntriple, septuple, multiple suns, we shall find power enough to go\nthrough the whole alphabet in geometrical ratio; and then in the\nclustered suns, galaxies, and nebul\u00e6, power enough still\nunrepresented by single letters to require all combinations of the\nalphabet of power. What is the significance of this single element\nof power? The answer of science to-day is \"correlation,\" the\nconstant evolution of one force from another. Heat is a mode of\nmotion, motion a result of heat. So far so good. But are we mere\nreasoners in a circle? Then we would be lost men, treading our round\nof death in a limitless forest. What is the ultimate? Reason [Page\n252] out in a straight line. No definition of matter allows it to\noriginate force; only mind can do that. Hence the ultimate force is\nalways mind. Carry your correlation as far as you please--through\nplanets, suns, nebul\u00e6, concretionary vortices, and revolving\nfire-mist--there must always be mind and will beyond. Some of that\nwillpower that works without exhaustion must take its own force and\nrender it static, apparent. It may do this in such correlated\nrelation that that force shall go on year after year to a thousand\nchanging forms; but that force must originate in mind.\n\nGo out in the falling rain, stand under the thunderous Niagara,\nfeel the immeasurable rush of life, see the hanging worlds, and\ntrace all this--the carried rain, the terrific thunder with God's bow\nof peace upon it, and the unfailing planets hung upon nothing--trace\nall this to the orb of day blazing in perpetual strength, but stop\nnot there. Who _made_ the sun? Contrivance fills all thought. _Who_\nmade the sun? Nature says there is a mind, and that mind is Almighty.\nThen you have read the first syllables, viz., being and power.\n\nWhat is the continuous relation of the universe to the mind from\nwhich it derived its power? Some say that it is the relation of\na wound-up watch to the winder. It was dowered with sufficient\npower to revolve its ceaseless changes, and its maker is henceforth\nan absentee God. Is it? Let us have courage to see. For twenty\nyears one devotes ten seconds every night to putting a little force\ninto a watch. It is so arranged that it distributes that force\nover twenty-four hours. In that twenty years more power has been\nput into that watch than a horse could exert at once. But suppose\n[Page 253] one had tried to put all that force into the watch at\nonce: it would have pulverized it to atoms. But supposing the\nuniverse had been dowered with power at first to run its enormous\nrounds for twenty millions of years. It is inconceivable; steel\nwould be as friable as sand, and strengthless as smoke, in such\nstrain.\n\nWe have discovered some of the laws of the force we call gravitation.\nBut what do we know of its essence? How it appears to act we know a\nlittle, what it is we are profoundly ignorant. Few men ever discuss\nthis question. All theories are sublimely ridiculous, and fail to\npass the most primary tests. How matter can act where it is not,\nand on that with which it has no connection, is inconceivable.\n\nNewton said that anyone who has in philosophical matters a competent\nfaculty of thinking, could not admit for a moment the possibility\nof a sun reaching through millions of miles, and exercising there\nan attractive power. A watch may run if wound up, but how the\nwatch-spring in one pocket can run the watch in another is hard\nto see. A watch is a contrivance for distributing a force outside\nof itself, and if the universe runs at all on that principle, it\ndistributes some force outside of itself.\n\nLe Sage's theory of gravitation by the infinitive hail of atoms\ncannot stand a minute, hence we come back as a necessity of thought\nto Herschel's statement. \"It is but reasonable to regard gravity\nas a result of a consciousness and a will existent somewhere.\"\nWhere? I read an old book speaking of these matters, and it says\nof God, He hangeth the earth upon nothing; he upholdeth constantly\nall things by the word of his power. [Page 254] By him all things\nconsist or hold together. It teaches an imminent mind; an almighty,\nconstantly exerted power. Proof of this starts up on every side.\nThere is a recognized tendency in all high-class energy to\ndeteriorate to a lower class. There is steam in the boiler, but it\nwastes without fuel. There is electricity in the jar, but every\nparticle of air steals away a little, unless our conscious force is\nexerted to regather it. There is light in the sun, but infinite\nspace waits to receive it, and takes it swift as light can leap. We\nsaid that if the sun were pure coal, it would burn out in five\nthousand years, but it blazes undimmed by the million. How can it?\nThere have been various theories: chemical combustion, it has\nfailed; meteoric impact, it is insufficient; condensation, it is not\nproved; and if it were, it is an intermediate step back to the\noriginal cause of condensation. The far-seeing eyes see in the sun\nthe present active power of Him who first said, \"Let there be\nlight,\" and who at any moment can meet a Saul in the way to Damascus\nwith a light above the brightness of the sun--another noon arisen on\nmid-day; and of whom it shall be said in the eternal state of\nunclouded brightness, where sun and moon are no more, \"The glory of\nthe Lord shall lighten it, and the Lamb is the light thereof.\"\n\nBut suppose matter could be dowered, that worlds could have a\ngravitation, one of two things must follow: It must have conscious\nknowledge of the position, exact weight, and distance of every\natom, mass, and world, in order to proportion the exact amount of\ngravity, or it must fill infinity with an omnipresent attractive\npower, pulling in myriads of places at nothing; in [Page 255] a few\nplaces at worlds. Every world must exert an infinitely extended\npower, but myriads of infinities cannot be in the same space. The\nsolution is, one infinite power and conscious will.\n\nTo see the impossibility of every other solution, join in the long\nand microscopic hunt for the ultimate particle, the atom; and if\nfound, or if not found, to a consideration of its remarkable powers.\nBring telescopes and microscopes, use all strategy, for that atom\nis difficult to catch. Make the first search with the microscope:\nwe can count 112,000 lines ruled on a glass plate inside of an\ninch. But we are here looking at mountain ridges and valleys, not\natoms. Gold can be beaten to the 1/340000 of an inch. It can be\ndrawn as the coating of a wire a thousand times thinner, to the\n1/340000000 of an inch. But the atoms are still heaped one upon\nanother.\n\nTake some of the infusorial animals. Alonzo Gray says millions\nof them would not equal in bulk a grain of sand. Yet each of them\nperforms the functions of respiration, circulation, digestion,\nand locomotion. Some of our blood-vessels are not a millionth of\nour size. What must be the size of the ultimate particles that\nfreely move about to nourish an animal whose totality is too small\nto estimate? A grain of musk gives off atoms enough to scent every\npart of the air of a room. You detect it above, below, on every\nside. Then let the zephyrs of summer and the blasts of winter sweep\nthrough that room for forty years, bearing out into the wide world\nmiles on miles of air, all perfumed from the atoms of that grain\nof musk, and at the end of the forty years the weight of musk has\nnot appreciably diminished. [Page 256] Yet uncountable myriads on\nmyriads of atoms have gone.\n\nOur atom is not found yet. Many are the ways of searching for it\nwhich we cannot stop to consider. We will pass in review the properties\nwith which materialists preposterously endow it. It is impenetrable\nand indivisible, though some atoms are a hundred times larger than\nothers. Each has definite shape; some one shape, and some another.\nThey differ in weight, in quantity of combining power, in quality\nof combining power. They combine with different substances, in\ncertain exact assignable quantities. Thus one atom of hydrogen\ncombines with eighty of bromine, one hundred and sixty of mercury,\ntwo hundred and forty of boron, three hundred and twenty of silicon,\netc. Hence our atom of hydrogen must have power to count, or at\nleast to measure, or be cognizant of bulk. Again, atoms are of\ndifferent sorts, as positive or negative to electric currents.\nThey have power to take different shapes with different atoms in\ncrystallization; that is, there is a power in them, conscious or\notherwise, that the same bricks shall make themselves into stables\nor palaces, sewers or pavements, according as the mortar varies.\n\"No, no,\" you cry out; \"it is only according as the builder varies\nhis plan.\" There is no need to rehearse these powers much further;\nthough not one-tenth of the supposed innate properties of this\ninfinitesimal infinite have been recited--properties which are\nexpressed by the words atomicity, quantivilence, monad, dryad,\nunivalent, perissad, quadrivalent, and twenty other terms, each\nexpressing some endowment of power in this in visible atom. Refer\nto one more presumed ability, an ability [Page 257] to keep\nthemselves in exact relation of distance and power to each other,\nwithout touching.\n\nIt is well known that water does not fill the space it occupies.\nWe can put eight or ten similar bulks of different substances into\na glass of water without greatly increasing its bulk, some actually\ndiminishing it. A philosopher has said that the atoms of oxygen\nand hydrogen are probably not nearer to each other in water than\none hundred and fifty men would be if scattered over the surface\nof England, one man to four hundred square miles.\n\nThe atoms of the luminiferous ether are infinitely more diffused,\nand yet its interactive atoms can give four hundred millions of\nlight-waves a second. And now, more preposterous than all, each\natom has an attractive power for every other atom of the universe.\nThe little mote, visible only in a sunbeam streaming through a\ndark room, and the atom, infinitely smaller, has a grasp upon the\nwhole world, the far-off sun, and the stars that people infinite\nspace. The Sage of Concord advises you to hitch your wagon to a\nstar. But this is hitching all stars to an infinitesimal part of\na wagon. Such an atom, so dowered, so infinite, so conscious, is\nan impossible conception.\n\nBut if matter could be so dowered as to produce such results by\nmechanism, could it be dowered to produce the results of intelligence?\nCould it be dowered with power of choice without becoming mind?\nIf oxygen and hydrogen could be made able to combine into water,\ncould the same unformed matter produce in one case a plant, in\nanother a bird, in a third a man; and in each of these put bone,\nbrain, blood, and nerve in [Page 258] proper relations? Matter must\nbe mind, or subject to a present working mind, to do this. There\nmust be a present intelligence directing the process, laying the\ndead bricks, marble, and wood in an intelligent order for a living\ntemple. If we do put God behind a single veil in dead matter, in all\nliving things he must be apparent and at work. If, then, such a\nthing as an infinite atom is impossible, shall we not best\nunderstand matter by saying it is a visible representation of God's\npersonal will and power, of his personal force, and perhaps\nknowledge, set aside a little from himself, still possessed somewhat\nof his personal attributes, still responsive to his will. What we\ncall matter may be best understood as God's force, will, knowledge,\nrendered apparent, static, and unweariably operative. Unless matter\nis eternal, which is unthinkable, there was nothing out of which the\nworld could be made, but God himself; and, reverently be it said,\nmatter seems to retain fit capabilities for such source. Is not this\nthe teaching of the Bible? I come to the old Book. I come to that\nman who was taken up into the arcana of the third heaven, the holy\nof holies, and heard things impossible to word. I find he makes a\nclear, unequivocal statement of this truth as God's revelation to\nhim. \"By faith,\" says the author of Hebrews, \"we understand the\nworlds were framed by the word of God, so that things which are seen\nwere not made of things which do appear.\" In Corinthians, Paul\nsays--But to us there is but one God, the Father, of whom [as a\nsource] are all things; and one Lord Jesus Christ, by whom [as a\ncreative worker] are all things. So in Romans he says--\"For out of\nhim, and through him, and to him are all things, to whom be glory\nforever. Amen.\"\n\n[Page 259]\nGod's intimate relation to matter is explained. No wonder the forces\nrespond to his will; no wonder pantheism--the idea that matter is\nGod--has had such a hold upon the minds of men. Matter, derived\nfrom him, bears marks of its parentage, is sustained by him, and\nwhen the Divine will shall draw it nearer to himself the new power\nand capabilities of a new creation shall appear. Let us pay a higher\nrespect to the attractions and affinities; to the plan and power\nof growth; to the wisdom of the ant; the geometry of the bee; the\nmigrating instinct that rises and stretches its wings toward a\nprovided South--for it is all God's present wisdom and power. Let\nus come to that true insight of the old prophets, who are fittingly\ncalled seers; whose eyes pierced the veil of matter, and saw God\nclothing the grass of the field, feeding the sparrows, giving snow\nlike wool and scattering hoar-frost like ashes, and ever standing on\nthe bow of our wide-sailing world, and ever saying to all tumultuous\nforces, \"Peace, be still.\" Let us, with more reverent step, walk\nthe leafy solitudes, and say:\n\n                       \"Father, thy hand\n  Hath reared these venerable columns: Thou\n  Did'st weave this verdant roof. Thou did'st look down\n  Upon the naked earth, and forthwise rose\n  All these fair ranks of trees. They in Thy sun\n  Budded, and shook their green leaves in Thy breeze.\n\n               \"That delicate forest flower,\n  With scented breath and looks so like a smile,\n  Seems, as it issues from the shapeless mould,\n  An emanation of the indwelling life,\n  A visible token of the unfolding love\n  That are the soul of this wide universe.\"--BRYANT.\n\n[Page 260]\nPhilosophy has seen the vast machine of the universe, wheel within\nwheel, in countless numbers and hopeless intricacy. But it has\nnot had the spiritual insight of Ezekiel to see that they were\neveryone of them full of eyes--God's own emblem of the omniscient\nsupervision.\n\nWhat if there are some sounds that do not seem to be musically\nrhythmic. I have seen where an avalanche broke from the mountain side\nand buried a hapless city; have seen the face of a cliff shattered\nto fragments by the weight of its superincumbent mass, or pierced\nby the fingers of the frost and torn away. All these thunder down\nthe valley and are pulverized to sand. Is this music? No, but it\nis a tuning of instruments. The rootlets seize the sand and turn\nit to soil, to woody fibre, leafy verdure, blooming flowers, and\ndelicious fruit. This asks life to come, partake, and be made strong.\nThe grass gives itself to all flesh, the insect grows to feed the\nbird, the bird to nourish the animal, the animal to develop the\nman.\n\nNotwithstanding the tendency of all high-class energy to deteriorate,\nto find equilibrium, and so be strengthless and dead, there is,\nsomehow, in nature a tremendous push upward. Ask any philosopher,\nand he will tell you that the tendency of all endowed forces is\nto find their equilibrium and be at rest--that is, dead. He draws\na dismal picture of the time when the sun shall be burned out,\nand the world float like a charnel ship through the dark, cold\nvoids of space--the sun a burned-out char, a dead cinder, and the\nworld one dismal silence, cold beyond measure, and dead beyond\nconsciousness. The philosopher has wailed a dirge without [Page 261]\nhope, a requiem without grandeur, over the world's future. But\nnature herself, to all ears attuned, sings p\u00e6ans, and shouts to men\nthat the highest energy, that of life, does not deteriorate.\n\nMere nature may deteriorate. The endowments of force must spend\nthemselves. Wound-up watches and worlds must run down. But nature\nsustained by unexpendable forces must abide. Nature filled with\nunexpendable forces continues in form. Nature impelled by a magnificent\npush of life must ever rise.\n\nStudy her history in the past. Sulphurous realms of deadly gases\nbecome solid worlds; surplus sunlight becomes coal, which is reserved\npower; surplus carbon becomes diamonds; sediments settle until\nthe heavens are azure, the air pure, the water translucent. If\nthat is the progress of the past, why should it deteriorate in the\nfuture?\n\nThere is a system of laws in the universe in which the higher have\nmastery over the lower. Lower powers are constitutionally arranged\nto be overcome; higher powers are constitutionally arranged for\nmastery. At one time the water lies in even layers near the ocean's\nbed, in obedience to the law or power of gravitation. At another\ntime it is heaved into mountain billows by the shoulders of the\nwind. Again it flies aloft in the rising mists of the morning,\ntransfigured by a thousand rain bows by the higher powers of the\nsun. Again it develops the enormous force of steam by the power of\nheat. Again it divides into two light flying airs by electricity.\nAgain it stands upright as a heap by the power of some law in the\nspirit realm, whose mode of working we are not yet large enough\n[Page 262] to comprehend. The water is solid, liquid, gaseous on\nearth, and in air according to the grade of power operating upon it.\n\nThe constant invention of man finds higher and higher powers. Once\nhe throttled his game, and often perished in the desperate struggle;\nthen he trapped it; then pierced it with the javelin; then shot it\nwith an arrow, or set the springy gases to hurl a rifle-ball at\nit. Sometime he may point at it an electric spark, and it shall\nbe his. Once he wearily trudged his twenty miles a day, then he\ntook the horse into service and made sixty; invoked the winds,\nand rode on their steady wings two hundred and forty; tamed the\nsteam, and made almost one thousand; and if he cannot yet send his\nbody, he can his mind, one thousand miles a second. It all depends\nupon the grade of power he uses. Now, hear the grand truth of nature:\nas the years progress the higher grades of power increase. Either\nby discovery or creation, there are still higher class forces to\nbe made available. Once there was no air, no usable electricity.\nThere is no lack of those higher powers now. The higher we go the\nmore of them we find. Mr. Lockyer says that the past ten years have\nbeen years of revelation concerning the sun. A man could not read\nin ten years the library of books created in that time concerning\nthe sun. But though we have solved certain problems and mysteries,\nthe mysteries have increased tenfold.\n\nWe do not know that any new and higher forces have been added to\nmatter since man's acquaintance with it. But it would be easy to\nadd any number of them, or change any lower into higher. That is the\n[Page 263] meaning of the falling granite that becomes soil, of the\npulverized lava that decks the volcano's trembling sides with\nflowers; that is the meaning of the grass becoming flesh, and of all\nhigh forces constitutionally arranged for mastery over lower. Take\nthe ore from the mountain. It is loose, friable, worthless in\nitself. Raise it in capacity to cast-iron, wrought-iron, steel, it\nbecomes a highway for the commerce of nations, over the mountains\nand under them. It becomes bones, muscles, body for the inspiring\nsoul of steam. It holds up the airy bridge over the deep chasm. It\nis obedient in your hand as blade, hammer, bar, or spring. It is\ninspirable by electricity, and bears human hopes, fears, and loves\nin its own bosom. It has been raised from valueless ore. Change it\nagain to something as far above steel as that is above ore. Change\nall earthly ores to highest possibility; string them to finest\ntissues, and the new result may fit God's hand as tools, and thrill\nwith his wisdom and creative processes, a body fitted for God's\nspirit as well as the steel is fitted to your hand. From this world\ntake opacity, gravity, darkness, bring in more mind, love, and God,\nand then we will have heaven. An immanent God makes a plastic world.\n\nWhen man shall have mastered the forces that now exist, the original\nCreator and Sustainer will say, \"Behold, I create all things new.\"\nNature shall be called nearer to God, be more full of his power.\nTo the long-wandering \u00c6neas, his divine mother sometimes came to\ncheer his heart and to direct his steps. But the goddess only showed\nherself divine by her departure; only when he stood in desolation\ndid the hero know he had [Page 264] stood face to face with divine\npower, beauty, and love. Not so the Christian scholars, the\nwanderers in Nature's bowers to-day. In the first dawn of discovery,\nwe see her full of beauty and strength; in closer communion, we find\nher full of wisdom; to our perfect knowledge, she reveals an\nindwelling God in her; to our ardent love, she reveals an indwelling\nGod in us.\n\nBut the evidence of the progressive refinements of habitation is no\nmore clear than that of progressive refinement of the inhabitant:\nthere must be some one to use these finer things. An empty house is\nnot God's ideal nor man's. The child may handle a toy, but a man\nmust mount a locomotive; and before there can be New Jerusalems\nwith golden streets, there must be men more avaricious of knowledge\nthan of gold, or they would dig them up; more zealous for love\nthan jewels, or they would unhang the pearly gates. The uplifting\nrefinement of the material world has been kept back until there\nshould appear masterful spirits able to handle the higher forces.\nDoors have opened on every side to new realms of power, when men\nhave been able to wield them. If men lose that ability they close\nagain, and shut out the knowledge and light. Then ages, dark and\nfeeble, follow.\n\nSome explore prophecy for the date of the grand transformation\nof matter by the coming of the Son of Man, for a new creation. A\nlittle study of nature would show that the date cannot be fixed.\nA little study of Peter would show the same thing. He says, \"What\nmanner of persons ought ye to be, in all holy conversation and\ngodliness, looking for and hastening the coming [Page 265] of the\nday of God, wherein the heavens being on fire shall be dissolved,\nand the elements shall melt with fervent heat? Nevertheless we,\naccording to his promise, look for a new heaven and a new earth.\"\n\nThe idea is, that the grand transformation of matter waits the\nreadiness of man. The kingdom waits the king. The scattered cantons\nof Italy were only prostrate provinces till Victor Emanuel came,\nthen they were developed into united Italy. The prostrate provinces\nof matter are not developed until the man is victor, able to rule\nthere a realm equal to ten cities here. Every good man hastens the\ncoming of the day of God and nature's renovation. Not only does\ninference teach that there must be finer men, but fact affirms\nthat transformation has already taken place. Life is meant to have\npower over chemical forces. It separates carbon from its compounds\nand builds a tree, separates the elements and builds the body,\nholds them separate until life withdraws. More life means higher\nbeing. Certainly men can be refined and recapacitated as well as\nore. In Ovid's \"Metamorphoses\" he represents the lion in process of\nformation from earth, hind quarters still clay, but fore quarters,\nhead, erect mane, and blazing eye--live lion--and pawing to get\nfree. We have seen winged spirits yet linked to forms of clay,\nbut beating the celestial air, endeavoring to be free; and we have\nseen them, dowered with new sight, filled with new love, break\nloose and rise to higher being.\n\nIn this grand apotheosis of man which nature teaches, progress\nlias already been made. Man has already outgrown his harmony with\nthe environment of mere matter. He has given his hand to science, and\nbeen lifted up above the earth into the voids of infinite space. He\n[Page 266] has gone on and on, till thought, wearied amidst the\ninfinities of velocity and distance, has ceased to note them. But he\nis not content; all his faculties are not filled. He feels that his\nfuture self is in danger of not being satisfied with space, and\nworlds, and all mental delights, even as his manhood fails to be\nsatisfied with the materiel toys of his babyhood. He asks for an\nAuthor and Maker of things, infinitely above them. He has seen\nwisdom unsearchable, power illimitable; but he asks for personal\nsympathy and love. Paul expresses his feeling: every creature--not\nthe whole creation--groaneth and travaileth in pain together until\nnow, waiting for the adoption--the uplifting from orphanage to\nparentage--a translation out of darkness into the kingdom of God's\ndear Son. He hears that a man in Christ is a new creation: old\nthings pass away, all things become new. There is then a possibility\nof finding the Author of nature, and the Father of man. He begins\nhis studies anew. Now he sees that all lines of knowledge converge\nas they go out toward the infinite mystery; sees that these\nconverging lines are the reins of government in this world; sees the\nconverging lines grasped by an almighty hand; sees a loving face and\nform behind; sees that these lines of knowledge and power are his\npersonal nerves, along which flashes his will, and every force in\nthe universe answers like a perfect muscle.\n\nThen he asks if this Personality is as full of love as of power.\nHe is told of a tenderness too deep for tears, a love that has the\nCross for its symbol, and a dying cry for its expression: seeking\nit, he is a new creation. He sees more wondrous things in the Word\nthan in the [Page 267] world. He comes to know God with his heart,\nbetter than he knows God's works by his mind.\n\nEvery song closes with the key-note with which it began, and the\nbrief cadence at the close hints the realms of sound through which\nit has tried its wings. The brief cadence at the close is this:\nAll force runs back into mind for its source, constant support,\nand uplifts into higher grades.\n\nMr. Grove says, \"Causation is the will, creation is the act, of God.\"\nCreation is planned and inspired for the attainment of constantly\nrising results. The order is chaos, light, worlds, vegetable forms,\nanimal life, then man. There is no reason to pause here. This is\nnot perfection, not even perpetuity. Original plans are not\naccomplished, nor original force exhausted. In another world, free\nfrom sickness, sorrow, pain, and death, perfection of abode is\noffered. Perfection of inhabitant is necessary; and as the creative\npower is everywhere present for the various uplifts and refinements\nof matter, it is everywhere present with appropriate power for\nthe uplifting and refinement of mind and spirit.\n\n\n\n\n[Page 269]\nSUMMARY OF LATEST DISCOVERIES AND CONCLUSIONS.\n\n_Movements on the Sun._--The discovery and measurement of the up-rush,\ndown-rush, and whirl of currents about the sunspots, also of the\ndetermination of the velocity of rotation by means of the spectroscope,\nas described (page 53), is one of the most delicate and difficult\nachievements of modern science.\n\n_Movement of Stars in Line of Sight_ (page 51).--The following\ntable shows this movement of stars, so far as at present known:\n\n ---------------------------------------------------------------\n|        APROACHING.           ||          RECEDING.            |\n|------------------------------||-------------------------------|\n|  Map. |   Name.   |   Rate   ||  Map.  |   Name.   |  Rate    |\n|       |           | per sec. ||        |           | per sec. |\n|-------|-----------|----------||--------|-----------|----------|\n|Fig. 71|Arcturus   | 55 miles ||Fig. 69 |Sirius     | 20 miles |\n| \"   72|Vega       | 50   \"   ||Fr'piece|Betelguese | 22   \"   |\n| \"   73|a Cygni    | 39   \"   ||    \"   |Rigel      | 15   \"   |\n| \"   69|Pollux     | 49   \"   ||Fig. 69 |Castor     | 25   \"   |\n| \"   67|Dubhe      | 46   \"   || \"   70 |Regulus    | 15   \"   |\n ---------------------------------------------------------------\n\n_Sun's Appearance._--This was formerly supposed to be an even,\nregular, dazzling brightness, except where the spots appeared.\nBut the sun's surface is now known to be mottled with what are\ncalled rice grains or willow leaves. But the rice grains are as\nlarge as the continent of America. The spaces between are called\npores. They constitute an innumerable number of small spots. This\nappearance of the general surface is well portrayed in the cut\non page 92.\n\n_Close Relation between Sun and Earth._-Men always knew that the\nearth received light from the sun. They subsequently discovered\nthat the earth was momentarily held by the power [Page 270] of\ngravitation. But it is a recent discovery that the light is one of\nthe principal agents in chemical changes, in molecular grouping and\nworld-building, thus making all kinds of life possible (p. 30-36).\nThe close connection of the sun and the earth will be still farther\nshown in the relation of sun-spots and auroras. One of the most\nsignificant instances is related on page 19, when the earth felt the\nfall of bolides upon the sun. Members of the body no more answer to\nthe heart than the planets do to the sun.\n\n_Hydrogen Flames._--It has been demonstrated that the sun flames\n200,000 miles high are hydrogen in a state of flaming incandescence\n(page 85).\n\n_Sun's Distance._--The former estimate, 95,513,794 miles, has been\nreduced by nearly one-thirtieth. Lockyer has stated it as low as\n89,895,000 miles, and Proctor, in \"Encyclop\u00e6dia Britannica,\" at\n91,430,000 miles, but discovered errors show that these estimates\nare too small. Newcomb gives 92,400,000 as within 200,000 miles\nof the correct distance. The data for a new determination of this\ndistance, obtained from the transit of Venus, December 8th, 1874,\nhave not yet been deciphered; a fact that shows the difficulty\nand laboriousness of the work. Meanwhile it begins to be evident\nthat observations of the transit of Venus do not afford the best\nbasis for the most perfect determination of the sun's distance.\n\nSince the earth's distance is our astronomical unit of measure, it\nfollows that all other distances will be changed, when expressed\nin miles, by this ascertained change of the value of the standard.\n\n_Oxygen in the Sun._--In 1877 Professor Draper announced the discovery\nof oxygen lines in the spectrum of the sun. The discovery was doubted,\nand the methods used were criticised by Lockyer and others, but\nlater and more delicate experiments substantiate Professor Draper's\nclaim to the discovery. The elements known to exist in the sun\nare salt, iron, hydrogen, [Page 271] magnesium, barium, copper,\nzinc, cromium, and nickel. Some elements in the sun are scarcely, if\nat all, discoverable on the earth, and some on the earth not yet\ndiscernible in the sun.\n\n_Substance of Stars._--Aldebaran (_Frontispiece_) shows salt, magnesium,\nhydrogen, calcium, iron, bismuth, tellurium, antimony, and mercury.\nSome of the sun's metals do not appear. Stars differ in their very\nsubstance, and will, no doubt, introduce new elements to us unknown\nbefore.\n\nThe theory that all nebul\u00e6 are very distant clusters of stars is\nutterly disproved by the clearest proof that some of them are only\nincandescent gases of one or two kinds.\n\n_Discoveries of New Bodies._--Vulcan, the planet nearest the sun\n(page 138). The two satellites of Mars were discovered by Mr. Hall,\nU. S. Naval Observatory, August 11th, 1877 (page 161). \"The outer\none is called Diemas; the inner, Phobus.\n\nSir William Herschel thought he discovered six satellites of Uranus.\nThe existence of four of them has been disproved by the researches of\nmen with larger telescopes. Two new ones, however, were discovered\nby Mr. Lassell in 1846.\n\n_Saturn's Rings_ are proved to be in a state of fluidity and contraction\n(page 171).\n\n_Meteors and Comets._--The orbits of over one hundred swarms of\nmeteoric bodies are fixed: their relation to, and in some cases\nindentity with, comets determined. Some comets are proved to be\nmasses of great weight and solidity (page 133).\n\n_Aerolites._-Some have a texture like our lowest strata of rocks.\nThere is a geology of stars and meteors as well as of the earth. M.\nMeunier has just received the Lalande Medal from the Paris Academy\nfor his treatise showing that, so far as our present knowledge can\ndetermine, some of these meteors once belonged to a globe developed\nin true geological epochs, and which has been separated into fragments\nby agencies with which we are not acquainted.\n\n[Illustration: Fig. 82.--Horizontal Pendulum.]\n\n_The Horizontal Pendulum._--This delicate instrument is [Page 272]\nrepresented in Fig. 82. It consists of an upright standard, strongly\nbraced; a weight, _m_, suspended by the hair-spring of a watch, B D,\nand held in a horizontal position by another watch-spring, A C. The\nweight is deflected from side to side by the slightest influence.\nThe least change in the level of a base thirty-nine inches long that\ncould be detected by a spirit-level is 0\".1 of an arc--equal to\nraising one end 1/2068 of an inch. But the pendulum detects a\nraising of one end 1/36000000 of an inch. To observe the movements\nof the pendulum, it is kept in a dark room, and a ray of light is\ndirected to the mirror, _m_, and thence reflected upon a screen.\nThus the least movement may be enormously magnified, and read and\nmeasured by the moving spot on the screen. It has been discovered\nthat when the sun rises it has sufficient attraction to incline this\ninstrument to the east; when it sets, to incline it to the west. The\nsame is true of the moon. When either is exactly overhead or\nunderfoot, of course there is no deflection. The mean deflection\ncaused by the moon at rising or setting is 0\".0174; by the sun,\n0\".008. Great results are expected from this instrument hardly known\nas yet: among others, whether gravitation acts instantly or consumes\ntime in coming from the sun. This will be shown by the time of the\nchange of the pendulum from east to west when the sun reaches the\nzenith, and _vice versa_ when it crosses the nadir. The sun will be\nbest studied without light, in the quiet and darkness of some deep\nmine.\n\n[Page 273]\n_Light of Unseen Stars._--From careful examination, it appears\nthat three-fourths of the light on a fine starlight night comes\nfrom stars that cannot be discerned by the naked eye. The whole\namount of star light is about one-eightieth of that of the full\nmoon.\n\n_Lateral Movements of Stars_, page 226-28.\n\n_Future Discoveries_--_A Trans-Neptunian Planet._--Professor Asaph\nHall says: \"It is known to me that at least two American astronomers,\narmed with powerful telescopes, have been searching quite recently for\na trans-Neptunian planet. These searches have been caused by the fact\nthat Professor Newcomb's tables of Uranus and Neptune already begin\nto differ from observation. But are we to infer from these errors of\nthe planetary tables the existence of a trans-Neptunian planet? It\nis possible that such a planet may exist, but the probability is, I\nthink, that the differences are caused by errors in the theories of\nthese planets. * * * A few years ago the remark was frequently made\nthat the labors of astronomers on the solar system were finished, and\nthat henceforth they could turn their whole attention to sidereal\nastronomy. But to-day we have the lunar theory in a very discouraging\ncondition, and the theories of Mercury, Jupiter, Saturn, Uranus,\nand Neptune all in need of revision; unless, indeed, Leverrier's\ntheories of the last two planets shall stand the test of observation.\nBut, after all, such a condition of things is only the natural\nresult of long and accurate series of observations, which make\nevident the small inequalities in the motions, and bring to light\nthe errors of theory.\"\n\nFuture discoveries will mostly reveal the laws and conditions of\nthe higher and finer forces. Already Professor Loomis telegraphs\ntwenty miles without wire, by the electric currents between mountains.\nWe begin to use electricity for light, and feel after it for a\nmotor. Comets and Auroras show its presence between worlds, and\nin the interstellar spaces. Let another Newton arise.\n\n[Page 274]\n               SOME ELEMENTS OF THE SOLAR SYSTEM\n ------------------------------------------------------------------------\n|           |        |            |     Mean Dist.    |         |        |\n|           |        |            |     from Sun.     |         |        |\n|           |        |            |-------------------|  Mean   |Density.|\n|           |        |            | Earth's|          |Diameter |[Earth] |\n|   Name.   | Sign.  |   Masses.  |  Dist. | Millions |in Miles.|  = 1.  |\n|           |        |            |  as 1. | of Miles.|         |        |\n|-----------|--------|------------|--------|----------|---------|--------|\n| Sun       |[Symbol]|    Unity   |        |          | 860,000 | 0.255  |\n| Mercury   |[Symbol]|1/5000000(?)|  0.387 |    35-3/4|   2,992 | 1.21   |\n| Venus     |[Symbol]|  1/425000  |  0.723 |    66-3/4|   7,660 | 0.85   |\n| Earth     |[Symbol]|  1/326800  |  1.    |    92-1/3|   7,918 | 1.     |\n| Mars      |[Symbol]|  1/2950000 |  1.523 |   141    |   4,211 | 0.737  |\n| Asteroids |  (No.) |            |        |          |         |        |\n| Jupiter   |[Symbol]|   1/1047   |  5.203 |   480    |  86,000 | 0.243  |\n| Saturn    |[Symbol]|   1/3501   |  9.538 |   881    |  70,500 | 0.133  |\n| Uranus    |[Symbol]|  1/22600   | 19.183 |  1771    |  31,700 | 0.226  |\n| Neptune   |[Symbol]|  1/19380   | 30.054 |  2775    |  34,500 | 0.204  |\n ------------------------------------------------------------------------\n\n -------------------------------------------------------------\n|           |               | Gravity  |           |          |\n|           |     Axial     |    at    |           | Orbital  |\n|           |    Revolu-    | Surface. |  Periodic | Velocity |\n|   Name.   |     tion      | [Earth]  |    Time.  | in Miles |\n|           |               |   = 1    |           | per sec. |\n|-----------|---------------|----------|-----------|----------|\n| Sun       | 25 to 26d     |  27.71   |           |          |\n| Mercury   | 24h 5m(?)     |   0.46   |   87.97d  |  29.55   |\n| Venus     | 23h 21m(?)    |   0.82   |  224.70d  |  21.61   |\n| Earth     | 23h 56m 4s    |   1.     |  365.26d  |  18.38   |\n| Mars      | 24h 37m 22.7s |   0.39   |  686.98d  |  14.99   |\n| Asteroids |               |          |           |          |\n| Jupiter   |  9h 55m 20s   |   2.64   |  11.86yrs |   8.06   |\n| Saturn    |    10h 14m    |   1.18   |  29.46yrs |   5.95   |\n| Uranus    |    Unknown.   |   0.90   |  84.02yrs |   4.20   |\n| Neptune   |    Unknown.   |   0.89   | 164.78yrs |   3.36   |\n -------------------------------------------------------------\n\n[Page 275]\n              EXPLANATION OF ASTRONOMICAL SYMBOLS.\n\n                     SIGNS OF THE ZODIAC\n\n   0. [Symbol] Aries     0\u00b0  |   VI. [Symbol] Libra        180\u00b0\n   I. [Symbol] Taurus   30   |  VII. [Symbol] Scorpio      210\n  II. [Symbol] Gemini   60   | VIII. [Symbol] Sagittarius  240\n III. [Symbol] Cancer   90   |   IX. [Symbol] Capricornus  270\n  IV. [Symbol] Leo     120   |    X. [Symbol] Aquarius     300\n   V. [Symbol] Virgo   150   |   XI. [Symbol] Pisces       330\n\n       *       *       *       *       *\n\n [Symbol]  Conjunction.      |          S.  Seconds of Time.\n [Symbol]  Quadrature.       |           \u00b0  Degrees.\n [Symbol]  Opposition.       |           '  Minutes of Arc.\n [Symbol]  Ascending Node.   |           \"  Seconds of Arc.\n [Symbol]  Descending Node.  |       R. A.  Right Ascension.\n       H.  Hours.            | Decl. or D.  Declination.\n       M.  Minutes of Time.  |    N. P. D.  Dist. From North Pole.\n\n               OTHER ABBREVIATIONS USED IN THE ALMANAC.\n\nS., South, _i.e._, crosses the meridian; M., morning; A, Afternoon;\nGr. H. L. N., greatest heliocentric latitude north, _i.e._, greatest\ndistance north of the ecliptic, as seen from the sun. [Symbols]\nInf., inferior conjunction; Sup., superior conjunction.\n\n              GREEK ALPHABET USED INDICATING THE STARS.\n\n      a, alpha.    | ae, eta.    | n, nu.       | t, tau.\n      b, beta.     | th, theta.  | x, xi.       | u, upsilon.\n      g, gamma.    | i, iota.    | o, omicron.  | ph, phi.\n      d, delta.    | k, kappa.   | p, pi.       | ch, chi.\n      e, epsilon.  | l, lambda.  | r, rho.      | ps, psi.\n      z, zeta.     | m, mu.      | s, sigma.    | o, omega.\n\n\n\n\n[Page 276]\nCHAUTAUQUA OUTLINE FOR STUDENTS.\n\nAs an aid to comprehension, every student should draw illustrative\nfigures of the various circles, planes, and situations described.\n(For example, see Fig. 45, page 112.) As an aid to memory, the\nportion of this outline referring to each chapter should be examined\nat the close of the reading, and this mere sketch filled up to a\nperfect picture from recollection.\n\nI. _Creative Processes._--The dial-plate of the sky. Cause or different\nweights--on sun, moon. Two laws of gravity. Inertia. Fall of earth\nto sun per second. Forward motion. Elastic attraction. Perturbation\nof moon; of Jupiter and Saturn. Oscillations of planets.\n\nII. _Light._--From condensation. Number of vibrations of red; violet.\nThermometer against air. Aerolite against earth. Two bolides against\nthe sun. Large eye. Velocity of light. Prism. Color means different\nvibrations. Music of light. Light reports substance of stars. Force\nof; bridge, rain, dispersion, intensities, reflection, refraction,\ndecomposition.\n\nIII. _Astronomical Instruments._--Refracting telescope. Reflecting;\nlargest. Spectroscope. Spectra of sun, hydrogen, sodium, etc. E\nmade G by approach; C by departure. Stars approach and recede.\n\nIV. _Celestial Measurements._-Place and time by stars. Degrees,\nminutes, seconds. Mapping stars. Mural circle. Slow watch. Hoosac\nTunnel. Fine measurements. Sidereal time. Spider-lines. Personal\nequation. Measure distance--height. Ten-inch base line. Parallax\nof sun, stars. Longitude at sea. Distance of Polaris, a Centauri,\n61 Cygni. Orbits of asteroids.\n\nV. _The Sun._--World on fire. Apparent size from planets. Zodiacal\nlight. Corona. Hydrogen--how high? Size. How many earths? Spots:\n1. Motion; 2. Edges; 3. Variable; 4. Periodic; 5. Cyclonic; 6.\nSize; 7. Velocities. What the sun does. Experiments.\n\nVI. _The Planets from Space._--North Pole. Speed. Sizes. Axial\nrevolution. Man's weight on. Seasons. Parallelism of axis. Earth\nnear [Page 277] sun in winter. Plane of ecliptic. Orbits inclined\nto. Earth rotates. Proof. Sun's path among stars. Position of\nplanets. Motion--direct, retrograde. Experiments.\n\nVII. _Meteors._--Size; number; cause of; above earth; velocity;\ncolors; number in space; telescopic view of. Aerolites: Systems\nof; how many known. Comets: Orbits; number of comets; Halley's;\nBiela's lost; Encke's. Resisting medium. Whence come comets? Composed\nof what? Amount of matter in. [Symbol].\n\nVIII. _The Planets._--How many? Uranus discovered? Neptune? Asteroids?\nVulcan? Distance from sun. Periodic time. Mercury: Elements; shapes,\nas seen from earth; transits. Venus: Elements; seen by day; how\nnear earth? how far from? phases; Galileo. Earth: Elements; in\nspace; Aurora; balance of forces. Tides: Main and subsidiary causes;\neastern shores; Mediterranean Sea. Moon: Elements; hoax; moves east;\nsee one side; three causes help to see more than half. Revolution:\nWhy twenty-nine and a half days: heat--cold; how much light? Craters\nand peaks lighted; measured. Eclipses--Why not every new and full\nmoon? Periodicity. Mars: Elements; how near earth? How far from?\nApparent size; ice-fields; which end most? Satellites--Asteroids:\nHow found? When? By whom? How many? Jupiter: Elements; trade-winds;\nhow much light received? Own heat. Satellites: How many? Colors.\nSaturn: Elements; habitability; rings; flux; satellites. Uranus:\nElements; discoverer; seen by; moon's motion. Neptune: Elements;\ndiscovered by; how? Review system.\n\nIX. _The Nebular Hypothesis._--State it; facts confirmatory.\nObjections--1. Heat; 2. Rotation; 3. Retrograde; 4. Martial moons;\n5. Star of 1876. Evolution: Gaps in; conclusion.\n\nX. _The Stellar System._-Motto. Man among stars; open page; starry\npoem; stars located; named. Thuban. Etanin. Constellations: Know\nthem; number of stars; double; e Lyr\u00e6, Sirius, Procyon, Castor,\n61 Cygni, g Virginis. Colored stars; change color. Clusters: Two\ntheories. Nebul\u00e6: Two visible; composed of; shapes; where? Variable\nstars. Sun. b Lyr\u00e6, Mira, Betelguese, Algol; cause. Temporary;\n1572. New star of 1866: Two theories. Star of 1876. Movements of\nstars; Sirius; sun; 1830 Groombridge. Stars near Pleiades: Orion,\nGreat Dipper, Southern Cross. Centre of gravity.\n\nXI. _The Worlds and the Word._--Rich. Number. Erroneous allusions.\nTruth before discovery: 1. A beginning; 2. Creation before arrangement;\n3. Light before sun; 4. Mountains under water; 5. Order of\ndevelopment; [Page 278] 6. Sphere of earth; 7. How upheld; 8. Number\nof stars; 9. Weight of air; 10. Meteorology; 11. Queries to Job; 12.\nSun to end of heaven; 13. View of Mitchell; 14. Herschel. What is\nmatter? Force? End of earth. Way to knowledge. Work of light.\nTransfiguration of matter. Uniformitarianism. A whisper of Him. Man\nfor mastery. Each a type of higher. Survival of fittest. Uranus.\nWorlds and Word one language.\n\nXII. _The Ultimate Force._--Universe shows power: 1. Rain; Niagara;\n2. Vegetable growth; 3. Worlds carried; 4. Sun; fill dome with worlds;\n5. Double suns; 6. Galaxies. Correlation. What ultimate? Mind and\nwill. What continuous relation? Watch. Theories of gravitation:\nNewton's, Le Sage's, Bible's. High-class energy deteriorates. Search\nfor atoms: 1. Microscope; 2. Gold; 3. Infusoria; 4. Musk. Properties\nof atoms: 1. Impenetrable; 2. Indivisible; 3. Shape; 4. Quality; 5.\nCrystallization; 6. Not touch each other; 7. Active; 8. Attractive;\n9. Intelligent. Whose? Relation of matter to God; rock to soil.\nPush upward. Highest has mastery. Man advances by highest. Matter\nrecapacitated. Refined habitations. Inhabitants. All force leads\nback to mind. Personal and infinite.\n\n\n\n\n[Page 279]\nGLOSSARY OF ASTRONOMICAL TERMS AND INDEX.\n\nABBREVIATIONS used in astronomies, 275.\nABERRATION OF LIGHT (_a wandering away_), an apparent\n  displacement of a star, owing to the progressive motion of light\n  combined with that of the earth and its orbit, 199.\nAEROLITE (_air-stone_), 122.\nAIR, refraction of the, 40.\nALGOL, the variable star, 222.\nALMANAC, Nautical, 71; explanation of signs used, 275.\nALPHABET, Greek, 275.\nALTITUDE, angular elevation of a body above the horizon.\nANGLE, difference in directions of two straight lines that meet.\nANNULAR (_ring-shaped_) ECLIPSES, 158; nebul\u00e6, 218, 220.\nAPHELION, the point in an orbit farthest from the sun.\nAPOGEE, the point of an orbit which is farthest from the earth.\nAPSIS, plural _apsides_, the line joining the aphelion and\n  perihelion points; or the major axis of elliptical orbits.\nARC, a part of a circle.\nASCENSION, RIGHT, the angular distance of a heavenly body from\n  the first point of Aries, measured on the equator.\nASTEROIDS (_star-like_), 162; orbits of interlaced, 74.\nASTRONOMICAL INSTRUMENTS, 43.\nASTRONOMY, use of, 57.\nATOM, size of, 255; power of, 256.\nAURORA BOREALIS, 143.\nAXIS, the line about which a body rotates.\nAZIMUTH, the angular distance of any point or body in the horizon\n  from the north or south points.\nBAILEY'S BEADS, dots of light on the edge of the moon seen in a\n  solar eclipse, caused by the moon's inequalities of surface.\nBASE LINE, 68.\nBIELA'S COMET, 129.\nBINARY SYSTEM, a double star, the component parts of which\n  revolve around their centre of gravity.\nBODE'S LAW of planetary distances is no law at all, but a study\n  of coincidences.\nBOLIDES, small masses of matter in space. They are usually\n  called meteors when luminous by contact with air, 120.\n[Page 280]\nCELESTIAL SPHERE, the apparent dome in which the heavenly bodies\n  seem to be set; appears to revolve, 3.\nCENTRE OF GRAVITY, the point on which a body, or two or more\n  related bodies, balances.\nCENTRIFUGAL FORCE (_centre fleeing_).\nCHROMOLITHIC PLATE of spectra of metals, to face 50.\nCIRCUMPOLAR STARS, map of north, 201.\nCOLORS OF STARS, 214.\nCOLURES, the four principal meridians of the celestial sphere\n  passing from the pole, one through each equinox, and one through\n  each solstice.\nCOMETS, 126; Halley's, 128; Biela's lost, 129; Encke's, 130;\n  constitution of, 131; will they strike the earth? 133.\nCONJUNCTION. Two or more bodies are in conjunction when they\n  are in a straight line (disregarding inclination of orbit) with the\n  sun. Planets nearer the sun than the earth are in inferior\n  conjunction when they are between the earth and the sun; superior\n  conjunction when they are beyond the sun.\nCONSTELLATION, a group of stars supposed to represent some figure:\n  circumpolar, 201; equatorial, for December, 202; for January, 203;\n  April, 204; June, 205; September, 206; November, 207; southern\n  circumpolar, 208.\nCULMINATION, the passage of a heavenly body across the meridian\n  or south point of a place; it is the highest point reached in its\n  path.\nCUSP, the extremities of the crescent form of the moon or an\n  interior planet.\nDECLINATION, the angular distance of a celestial body north or south\n  from the celestial equator.\nDEGREE, the 1/360 part of a circle.\nDIRECT MOTION, a motion from west to east among stars.\nDISK, the visible surface of sun, moon, or planets.\nDISTANCE OF STARS, 70.\nDOUBLE STARS, 210.\nEARTH, revolution of, 109; in space, 142; irregular figure, 145.\nECCENTRICITY OF AN ELLIPSE, the distance of either focus from centre\n  divided by half the major axis.\nECLIPSE (_a disappearance_), 157.\nECLIPTIC, the apparent annual path of the sun among the stars;\n  plane of, 106.\nEGRESS, the passing of one body off the disk of another.\nELEMENTS, the quantities which determine the motion of a planet:\n  data for predicting astronomical phenomena; table of solar, 274.\nELEMENTS, chemical, present in the sun, 270.\nELONGATION, the angular distance of a planet from the sun.\nEMERSION, the reappearance of a body after it has been eclipsed or\n  occulted by another.\n[Page 281]\nEQUATOR, terrestrial, the great circle half-way between the poles of\n  the earth. When the plane of this is extended to the heavens,\n  the line of contact is called the celestial equator.\nEQUINOX, either of the points in which the sun, in its apparent\n  annual course among the stars, crosses the equator, making days\n  and nights of equal length.\nEVOLUTION, materialistic, 182; insufficient, 189.\nFIZEAU determines the velocity of light, 23.\nFORCES, delicate balance of, 144.\nGALILEO, construction of his telescope, 43.\nGEOCENTRIC, a position of a heavenly body as seen or measured from\n  the earth's centre.\nGEODESY, the art of measuring the earth without reference to the\n  heavenly bodies.\nGOD, relation of, to the universe, 258.\nGRAVITATION, laws of, 6; extends to the stars, 13; theories of, 253.\nGRAVITY on different bodies, 6, 274.\nHELICAL, rising or setting of a star, as near to sunrise or sunset\n  as it can be seen.\nHELIOCENTRIC, as seen from the centre of the sun.\nHOOSAC TUNNEL, example of accuracy, 62.\nHORIZONTAL PENDULUM, 272.\nIMMERSION, the disappearance of one body behind another, or in\n  its shadow.\nINCLINATION OF AN ORBIT, the angle between its plane and the plane\n  of the ecliptic.\nINFERIOR CONJUNCTION, when an interior planet is between the earth\n  and the sun.\nJUPITER, apparent path of, in 1866, 112; elements of, 164;\n  satellites of, 165; positions of satellites, 166; elements of satellites,\n  166; the Jovian system, 167.\nKEPLER'S LAWS--1st, that the orbits of planets are ellipses, having\n  the sun or central body in one of the foci; 2d, the radius-vector\n  passes over equal spaces in equal times; 3d, the squares of the\n  periodic times of the planets are in proportion to the cubes of\n  their mean distances from the sun.\nLATITUDE, the angular distance of a heavenly body from the ecliptic.\nLIGHT, the child of force, 17; number of vibrations of, 18, 25;\n  velocity of, 22; undulatory and musical, 26; chemical force of, 30;\n  experiments with, 37; approach and departure of a light-giving\n  body measured, 51; aberration of, 199.\nLIMB, the edge of the disk of the moon, sun, or a planet.\nLONGITUDE. If a perpendicular be dropped from a body to the\n  ecliptic, its celestial longitude is the distance of the foot of the\n  perpendicular from the vertical equinox, counted toward the east;\n  mode of ascertaining terrestrial, 72.\nMAGELLANIC CLOUDS, 208.\n[Page 282]\nMARS, 159; snow spots of, 160; satellites of, 161.\nMASS, the quantity of matter a body contains.\nMEAN DISTANCE OF A PLANET, half the sum of the aphelion and\n  perihelion distances.\nMEASUREMENTS, celestial, 57.\nMERCURY, 138.\nMERIDIAN, terrestrial, of a place, a great circle of the heavens\n  passing through the poles, the zenith, and the north and south points\n  of the horizon; celestial, any great circle passing from one pole\n  to the other.\nMETEORS, 119; swarm of, meeting the earth, 118; explosion of, 120;\n  systems of, 123; relation of, to comets, 124.\nMICROMETER, any instrument for the accurate measurement of very\n  small distances or angles.\nMIND, origin of force, 252; continuous relation of, to the\n  universe, 252.\nMILKY WAY, 210, 215.\nMIRA, the Wonderful, 221.\nMOON, the, 151; greatest and least distance from the earth, 10;\n  telescopic appearance of, 155.\nMURAL CIRCLE, 61.\nNADIR, the point in the celestial sphere directly beneath our feet,\n  opposite to zenith.\nNEBUL\u00c6, 217.\nNEBULAR HYPOTHESIS, not atheistic, 182; stated, 182; confirmatory\n  facts, 183; objections to, 185.\nNEPTUNE, elements of, 175.\nNODE, the point in which an orbit intersects the ecliptic, or\n  other plane of reference; ascending, descending, line of, 107.\nOCCULTATION, the hiding of a star, planet, or satellite by the\n  interposition of a nearer body of greater angular magnitude.\nOPPOSITION. A superior planet is in opposition when the sun,\n  earth, and the planet are in a line, the earth being in the middle.\nORBIT, the path of a planet, comet, or meteor around the sun, or of\n  a satellite around a primary; inclination of, 106; earth's, seen\n  from the stars, 70.\nOUTLINE FOR STUDENTS, 276.\nPARALLAX, the difference of direction of a heavenly body as seen\n  from two points, as the centre of the earth and some point of its\n  surface, 69.\nPARALLELS, imaginary circles on the earth or in the heavens parallel\n  to the equator, having the poles for their centre.\nPERIGEE, nearest the earth; said of a point in an orbit.\nPERIHELION, the point of an orbit nearest the sun.\nPERIODIC TIME, time of a planet's, comet's, or satellite's\n  revolution.\nPERSONAL EQUATION, 65.\nPERTURBATION, the effect of the attractions of the planets or other\n[Page 283]\n  bodies upon each other, disturbing their regular motion; of Saturn\n  and Jupiter, 11; of asteroids, 13; of Uranus and Neptune, 176.\nPHASES, the portions of the illuminated half of the moon or\n  interior planet, as seen from the earth, called crescent, full, and\n  gibbous.\nPHOTOSPHERE of the sun, 89.\nPLANET (_a wanderer_), as seen from space, 99; speed of, 101;\n  size of, 102; movements retrograde and direct, 112.\nPOINTERS, the, 197.\nPOLE, NORTH, movement of, 198.\nPOLES, the extremities of an imaginary line on which a celestial\n  body rotates.\nQUADRANT, the fourth part of the circumference of a circle, or 90\u00b0.\nQUADRATURE, a position of the moon or other body when 90\u00b0 from\n  the sun.\nRADIANT POINT, that point of the heavens from which meteors seem\n  to diverge, 118.\nRADIUS-VECTOR, an imaginary line joining the sun and a planet or\n  comet in any part of its orbit.\nRAIN, weight of, 249.\nREFLECTING TELESCOPE, 44.\nREFRACTING TELESCOPE, 43.\nREFRACTION, a bending of light by passing through any medium, as\n  air, water, prism.\nRETROGRADE MOTION, the apparent movement of a planet from east\n  to west among the stars.\nREVOLUTION, the movement of bodies about their centre of gravity.\nROTATION, the motion of a body around its axis.\nSATELLITES, smaller bodies revolving around planets and stars.\nSATURN, elements of, 167; revolution of, 168; rings of, 169;\n  decreasing, 171; nature of, 171; satellites of, 172.\nSEASONS, of the earth, 102; of other planets, 105.\nSELENOGRAPHY (_lunography_), a description of the moon's\n  surface.\nSIGNS OF THE ZODIAC, the twelve equal parts, of 30\u00b0 each, into\n  which the zodiac is divided.\nSOLAR SYSTEM, view of, 100, 177.\nSOLSTICES, those points of the ecliptic which are most distant from\n  the equator. The sun passes one about June 21st, and the other\n  about December 21st, giving the longest days and nights.\nSPECTROSCOPE, 46.\nSPECTRUM OF SUN AND METALS, 50.\nSTARS, chemistry of, 28; distance of, 70-73; mode of naming, 196;\n  number of, 210; double and multiple, 210; colored, 214; clusters\n  of, 215; variable, 220; temporary, new, and lost, 223; movements\n  of lateral, 226; in line of sight, 269.\nSTATIONARY POINTS, places in a planet's orbit at which it has no\n  motion among the stars.\n[Page 284]\nSTELLAR SYSTEM, the, 195.\nSUMMARY OF RECENT DISCOVERIES, 269.\nSUN, fall of two meteoric bodies into, 19; light from contraction\n  of, 20; as seen from planets, 79; corona, 81; hydrogen flames of, 84;\n  condition of, 89; spots, 90; experiments, 95; apparent path among\n  the stars, 111; power of, 250.\nSYMBOLS USED IN ASTRONOMY, 275.\nTELESCOPE, refracting, 43; reflecting, 44; Cambridge equatorial, 46.\nTELESCOPIC WORK, clusters, 210; double stars, 212.\nTEMPORARY STARS, 223.\nTERMINATOR, the boundary-line between light and darkness on the\n  moon or a planet.\nTIDES, 146.\nTRANSIT, the passage of an object across some fixed line, as the\n  meridian, or between the eye of an observer and an apparently\n  larger object, as that of Mercury or Venus over the disk of the\n  sun, and the satellites of Jupiter over its disk; of a star, 65.\nULTIMATE FORCE, the, 249.\nURANUS, elements of, 173; moons of, retrograde, 174; perturbed by\n  Neptune, 176.\nVARIABLE STARS, 220.\nVENUS, 139.\nVERNIER, a scale to measure very minute distances.\nVERTICAL CIRCLE, one that passes through the zenith and nadir of\n  the celestial sphere. The prime vertical circle passes through the\n  east and west points of the horizon.\nVULCAN, discovery of, 137.\nWORLDS, THE, AND THE WORD, teach the same truth, 231-245.\nYEAR, the, length of, on any planet, is determined by the periodic\n  time.\nZENITH, the point in the celestial sphere directly overhead.\nZODIAC, a belt 18\u00b0 wide encircling the heavens, the ecliptic being\n  the middle. In this belt the larger planets always appear. In\n  the older astronomy it was divided into twelve parts of 30\u00b0\n  each, called signs of the zodiac.\nZODIACAL LIGHT, 80.\n\n\n\n\nTO FIND THE STARS IN THE SKY.\n\nDetach any of the following maps, appropriate to the time of year,\nhold it between you and a lantern out-of-doors, and you have an\nexact miniature of the sky. Or, better, cut squares of suitable\nsizes from the four sides of a box; put a map over each aperture;\nprovide for ventilation, and turn the box over a lamp or candle\nout-of-doors. Use an opera glass to find the smaller stars, if\none is accessible.\n\n[Illustration: Circumpolar Constellations. Always visible. In this\nposition.--January 20th, at 10 o'clock; February 4th, at 9 o'clock;\nand February 19th, at 8 o'clock.]\n\n[Illustration: Algol is on the Meridian, 51\u00b0 South of Pole.--At 10\no'clock, December 7th; 9 o'clock, December 22d; 8 o'clock, January\n5th.]\n\n[Illustration: Capella (45\u00b0 from Pole) and Rigel (100\u00b0) are on\nthe Meridian at 8 o'clock February 7th, 9 o'clock January 22d, and\nat 10 o'clock January 7th.]\n\n[Illustration: Regulus comes on the Meridian, 79\u00b0 south from the\nPole, at 10 o'clock March 23d, 9 o'clock April 8th, and at 8 o'clock\nApril 23d.]\n\n[Illustration: Arcturus comes to the Meridian, 70\u00b0 from the Pole,\nat 10 o'clock May 25th, 9 o'clock June 9th, and at 8 o'clock June\n25th.]\n\n[Illustration: Altair comes to the Meridian, 82\u00b0 from the Pole,\nat 10 o'clock P.M. August 18th, at 9 o'clock September 2d, and\nat 8 o'clock September 18th.]\n\n[Illustration: Fomalhaut comes to the Meridian, only 17\u00b0 from the\nhorizon, at 8 o'clock November 4th.]","title":"Recreations in Astronomy: With Directions for Practical Experiments and Telescopic Work","tradition":"scripture-revelation","translated_text":null,"word_count":67932}