{"collection":"philosophy-ethics","full_text_available":true,"graph_url":"https://unchartedknowledge.5gfusion.net/v2/api/page/gutenberg_62362/graph","html_url":"https://unchartedknowledge.5gfusion.net/v2/page/gutenberg_62362","id":"gutenberg_62362","license":"Public Domain (US)","rights_basis":"gutenberg_metadata_copyright_false","source":"gutenberg","source_url":"https://www.gutenberg.org/ebooks/62362","summary":null,"tags":["Astronomical models","Astronomy","Category: Philosophy & Ethics","Category: Science - Physics"],"text":"AN\n                          EPITOME of ASTRONOMY,\n                                  WITH\n                         _THE NEW DISCOVERIES_:\n                       INCLUDING AN ACCOUNT OF THE\n                              E\u00eddouran\u00edon,\n                                   OR\n                           TRANSPARENT ORRERY;\n                         (INVENTED BY A. WALKER)\n\n                      AS LECTURED UPON BY HIS SON,\n                              _W. WALKER_.\n\n                STARS TEACH AS WELL AS SHINE!    YOUNG.\n\n                OS HOMINI SUBLIME DEDIT; C\u0152LUMQUE TUERI\n                JUSSIT, ET ERECTOS AD SIDERA TOLLERE VULTUS.\n                                                    OVID MET. 1. 85.\n\n                         THE FOURTEENTH EDITION.\n\n                                Ipswich;\n                         PRINTED FOR THE AUTHOR,\n                         BY BURRELL AND BRANSBY;\n            AND SOLD BY J. ROBSON AND W. CLARKE, BOND-STREET;\n                 AND G. KEARSLEY, FLEET-STREET, LONDON.\n                                  1800.\n\n\n\n\nAN\n\n_EPITOME of ASTRONOMY_;\n\nAS ILLUSTRATED BY THE\n\nE\u00eddouran\u00edon,\n\nOR\n\nTRANSPARENT ORRERY.\n\n\nThis elaborate Machine is 20 feet diameter: it stands vertical before\nthe spectators; and its globes are so large, that they are distinctly\nseen in the most distant part of a Theatre. Every Planet and Satellite\nseems suspended in space, without any support; performing its annual\nand diurnal revolutions without any apparent cause. It is certainly the\nnearest approach to the magnificent simplicity of nature, and to its just\nproportions, as to magnitude and motion, of any Orrery yet made: and\nbesides being a most brilliant and beautiful spectacle, conveys to the\nmind the most sublime instruction: rendering astronomical truths so plain\nand intelligible, that even those who have not so much as thought upon\nthe subject, may acquire clear ideas of the laws, motions, appearances,\neclipses, transits, influences, &c. of the planetary system.\n\n\n\n\nScene 1.\n\n_THE SUN AND EARTH_:\n\nWith the Zodiacal Constellations.\n\n\nAs information is the primary object of this lecture, it is thought more\nuseful to exhibit PARTS of the solar system, separately, before a grand\ndisplay was made of the whole. This scene therefore, opens with only the\nSun and the Earth. The Sun seems suspended in the middle of the system,\nand by spots on his face, is seen to turn round on his axis in 25\u00bc days;\nlight issues from his orb in all directions; in the blaze of which is\nsuspended the Earth, turning on its axis to produce day and night, and\nrevolving round the Sun to produce the seasons: its axis inclines 23\u00bd\ndegrees from a perpendicular to the plane of its orbit; and by that axis\nkeeping parallel to itself during this annual journey, the northern and\nsouthern hemispheres are alternately addressed to the Sun; shewing, when\nit is summer in one, it is winter in the other, and _vice vers\u00e2_. This\nscene so naturally exhibits the cause of day, night, twilight, summer\nand winter, spring and autumn, long and short days, &c. that a bare\ninspection of the Machine is sufficient to convey the clearest idea of\nthese ph\u00e6nomena.\n\n       *       *       *       *       *\n\nThe Earth in this scene ought to be unshackled with meridians or\nparallels of latitude:\u2014to be a free and independent ball, with land and\nwater represented as they would appear to a distant spectator looking at\nthe real Earth. But as globes are seldom seen without these appendages, a\nglobe of two feet in diameter, equipped with meridians and parallels of\nlatitude (being requisite for illustration) will perform a diurnal and\nannual motion round the Sun, and explain the above ph\u00e6nomena on so large\na scale, that their effects on the smallest island may be seen from the\nmost distant part of the theatre.\n\nThis scene is surrounded by transparent paintings of the twelve signs of\nthe Zodiac, shewing how the Sun, or rather the Earth, enters and passes\nthro\u2019 Aries, Taurus, Gemini, Cancer, &c.\n\n       *       *       *       *       *\n\nAuxiliary scenes accompany this, to shew the principles of planetary\nmotion; the formation of the constellations and their allegorical\nhistory; the oblate, yet nearly globular figure of the Earth; how ships\nand mountains appear at sea; with ships moving round a large globe of six\nfeet diameter, &c. proving that the Earth can contain inhabitants on all\nsides, &c.\n\n\n\n\nScene 2.\n\n_SUN, EARTH, AND MOON_:\n\nPHASES AND ECLIPSES.\n\n\nConsists of the Sun, the Earth, and the Moon. The object of this scene\nis to display the cause of the waxing and waning of the Moon, and of\nsolar and lunar eclipses: for this purpose the Earth perform its annual\nand diurnal motions, and projects a conical shadow opposite to the Sun\nduring its journey round him. The Moon borrows her light from the Sun;\nand which, in reflection to the Earth, is not more than one three hundred\nthousandth part so strong: and performing her rotation round the Earth,\nevery 29D. 12H. 44M. will sometimes shew us more and sometimes less of\nthe enlightened part of her body. Hence, when she is between the Earth\nand the Sun, her dark side is towards us, and we lose sight of her, and\ncall this part of her period the CHANGE; but as she revolves round the\nEarth from West to East (the same way the Earth turns on its axis) in a\nfew days we see her above the Sun in the West, and seeing a small part of\nher enlightened face, call the appearance the Horned, or NEW Moon: (for\nher dark side, receiving no reflection of light from any neighbouring\nbody, cannot be seen except in very clear weather). As she proceeds on\nher monthly journey, when the Sun sets in the West, we see her near our\nmeridian, and then she appears an HALF Moon, and we say she is at the\nfirst quarter; as she approaches the FULL, more of her enlightened side\nmay be seen, and she assumes an OVAL or GIBBOUS appearance. At the FULL\nshe is opposite to the Sun, when the inhabitants of the Earth look at her\nin the same direction as the rays of that luminary, and of course see\nthe whole of her enlightened face. In performing the other half of her\njourney, she wanes; and exposing less and less of her enlighted side to\nus, again disappears.\n\nThis scene receives also auxiliary illustration, before the grand scene\nopens: and in maps of the Moon during its exhibition, particularly one\nof five feet diameter, made from telescopes of the largest magnifying\npowers, and laid down with the most minute correctness, with maps of\nthe appearance of the Earth as seen from the Moon, indicating from this\nsimilarity, that they are worlds of nearly similar construction.\n\nIn the thirteen revolutions she will make while the Earth travels round\nthe Sun, it will evidently appear that the Earth is a Moon to her, but\nappearing thirteen times as large as the Moon to us; that she does not\nshine by her own light; that she has no diversity of seasons; that she\nkeeps the same side always turned towards the Earth, and therefore turns\non her axis every 29\u00bd days; that her surface is mountainous[1]; and that\nshe shines without setting, every second fortnight, on the arctic or\nantarctic parts of our globe, during winter: a very sublime and simple\nprovision for the otherwise long continued darkness that at opposite\nseasons of the year would invelope the polar regions of the Earth.\n\nIf the Moon moved in the same plane or level with the Earth, we should\nhave an eclipse every full and change; but as she travels 5\u00be degrees to\nthe North of it, and the same to the South of it, every lunation, she\nonly crosses the plane of the Earth\u2019s orbit in two places, which points\nof intersection (called the Moon\u2019s NODES) though in a trackless path,\nmove 19\u00be degrees towards the West every year, and therefore pass round\nthe Heavens in 18 years and 225 days; which is the golden number of our\ncalendar. Hence, when one of these nodes is between the Earth and the Sun\nat the change, the Moon\u2019s shadow is thrown on the Earth, and she eclipses\nthe Sun; and if she comes to the full when either node is opposite to the\nSun, she falls into the Earth\u2019s shadow, and loses for a short time her\nborrowed light: hence, as she mostly passes above or below the Earth\u2019s\nshadow, we have Eclipses very seldom. These ph\u00e6nomena are produced in the\nEidouranion as they are in nature, and perfectly evident on inspection.\n\n\n\n\nScene 3.\n\n_THEORY OF TIDES_, ILLUSTRATED.\n\n\nThis Scene also consists of the Sun, the Earth, and the Moon. But the\nintention is to shew how the Earth and Moon agitate each other round\ntheir common centre of gravity, causing two tides every 25 hours. It is\na circumstance truly astonishing, to see in calm weather, and under a\nserene sky, the violent agitation of the great fluid mass of the ocean,\nwhose waves roll against the shore with so grand impetuosity.\u2014This\nspectacle invites to reflection, and rouses a desire to penetrate\ninto its cause: hence the Earth\u2019s THREE-FOLD motion appears in this\nscene:\u2014that, on its axis, to produce day and night: that, round the\nSun, to produce the year and our seasons; and that, round the centre\nof gravity with the Moon, to produce spring and neap tides, by their\ncombined and opposite influences. The Moon is so near the Earth (240,000\nmiles at a medium) in comparison of the Sun (near 100 millions of miles)\nthat the Moon\u2019s attraction on the waters of the ocean and on the air of\nour atmosphere (for there are tides in both) is to that of the Sun as\nten is to three. So at the change of the Moon, the attraction of the Sun\nand Moon being in the same direction, a power of thirteen influences the\nsea, and we have SPRING tides; but at the quarters of the Moon, the two\nluminaries counteract the attractions of each other, so the Sun\u2019s power\nof three being taken from the Moon\u2019s of ten, leaves only seven operating\nupon the sea, and NEAP tides take place.\n\nA tumbler filled with water, may be whirled by a string vertically round\nthe head, without any danger of the water falling out of it. Those parts\nof the Earth that come successively OPPOSITE to the Moon, perform a much\nlarger circle round the centre of gravity, than the parts immediately\nUNDER the Moon: hence the waters opposite the Moon are THROWN OFF, as it\nwere, by their centrifugal motion, and rise above the common level, as\nwell as the waters exposed to the Moon\u2019s immediate attraction; thus two\ntides are produced in 25 hours, opposite to each other; and by the Earth\nturning through those protuberances, its waters rise and fall.\n\nThe Sun would produce two small, but similar tides, if the Earth had no\nMoon; therefore at the full of the Moon the Sun\u2019s centrifugal tide being\nreinforced by the Moon\u2019s attraction, and the Moon\u2019s centrifugal tide\nbeing also assisted by the Sun\u2019s attraction, spring tides take place at\nthe full, as well as at the change, of the Moon.\n\n    \u261e This Scene also receives collateral assistance, exhibiting\n    and explaining the setting of the tides in all the large oceans\n    and the principal seas of the Earth.\n\n\n\n\nScene 4.\n\n_THE SOLAR SYSTEM._\n\n\nThis displays the whole Copernican or Solar System, with every planet and\nsatellite in diurnal and annual motion! With awe and deference I offer\nthis daring but humble transcript of creation! Enough, if one idea can be\nadded, to the ingenuous mind, of the attributes and perfections of the\nDeity.\n\nThe SUN, a huge globe of fire (957,942 miles diameter, and consequently\na million times as large as our Earth, and intended to give light,\nheat, and vegetation, to seven primary and at least eighteen secondary\nworlds) is placed in the centre of the system; and by spots on his disk\nis discovered to turn on his axis in about 25 of our days. These spots\ncannot be permanently fixed, because they are frequently altering in\ntheir shape, situation, number, &c. tho\u2019 some have supposed they have\nseen small indentations on the edge of the Sun, as the spots have passed\nit, and conjectured that a fluid matter surrounded a dark nucleus, which\nsometimes becoming bare, might occasion the transient appearance and\ndisappearance of the spots.\n\nMERCURY is the first planet in the order of the system; about 3498\nmiles diameter: he moves round the Sun with the greatest velocity of\nany of the Planets familiar to our system (as being nearest the Sun) in\nabout 88 of our days; at the rate of 110,680 English miles every hour,\nbut the angle of his distance from the Sun, as seen by us, is so small,\nthat unless by the telescope, we can seldom discern him[2]; (and even\nthen an equatorial instrument to direct to its place, as indicated by\nthe Ephemeris, will be requisite;) and when we do, it is for so short a\ntime, and in twilight, that we can discover no spots on his face, and\ntherefore to this hour know nothing of the length of his days and nights:\nwe see him partially enlightened like the Moon, sometimes like a small\ncrescent, in other situations half enlightened, and sometimes gibbous or\noval, and are therefore certain he derives his light from the Sun, as she\ndoes: so that no doubt he is a fellow world, with inhabitants adapted to\nthe heat of his situation: altho\u2019 this heat is seven times as great as\nthat of the Earth. He is not much larger than the Moon. Our Earth, viewed\nfrom Mercury, must appear much larger and more luminous than any of the\nPlanets, except Venus, appears to us.\n\nVENUS is the next planet in the order of the system, and distinguished\nby her _superior brilliancy_, as the Sun\u2019s light is twice as great to\nthis planet as to the Earth; from this cause she is sometimes visible to\nthe naked eye in full day-light. She is about 70 millions of miles from\nthe Sun, or about twice the distance of Mercury; and like him, but much\nlonger and more conspicuously, appears under the different phases of the\nMoon. These, as we have said, are proofs that both planets borrow their\nlight from the Sun. The orbits of these planets (as well as those of the\nrest of the system) are inclined to the orbit of the Earth. Hence when\nVenus and Mercury are found in the nodes of their orbits between the\nEarth and Sun, they are transferred upon the Sun\u2019s face like small round\nblack spots, and which in fact are partial Eclipses of the Sun; these are\ncalled the TRANSITS of Mercury, or Venus.\n\nVenus is a little larger than the Earth, or 9360 miles diameter;\nand moves round the Sun in 224\u00bd of our days, at the rate of 80,955\nmiles every hour. From faint spots seen upon her surface, Mr. Shroeter\napprehends she revolves on her axis in 23 hours, 21 minutes; that her\nsurface is irregular like that of the Moon, and some of her mountains\nfour miles high. The atmosphere of Venus has been calculated to be 50\nmiles high: and the Sun would appear to the inhabitants of this planet\ntwice as large as to us. When Venus is to the west of the Sun, she is\na morning star; when to the east of him, an evening star: her orbit or\ntrack is included by the Earth\u2019s, and as both move the same way, she\nappears to be on one side of the Sun longer than the 224\u00bd days she is in\ngoing round him. The axis of Venus is said by some astronomers to incline\n75 degrees to the axis of her orbit: and therefore her seasons vary very\nfast, the Sun passing over more of her from pole to pole in one day, than\nover the Earth in a quarter of a year. Hence the heated places of this\nplanet have time to cool: which suggest to our ideas that provision has\nbeen made for inhabitants, that they might not suffer by their vicinity\nto the Sun; this circumstance also gives her two winters and two summers\nat her equator, and indicates her inhabited. The discovery lately made\nby Mr. Shroeter, of a light faintly extended beyond the bounds of direct\nsolar illumination, when she has her falcated appearance like the Moon\nnear to her change, strengthens this probability: as these are signs of\ntwilight, and of an atmosphere. This astronomer has also observed her\nto have considerable mountains; another character of a globe suited for\nhabitation.\n\nThe EARTH is the third planet in the order of the system: 8244 miles\ndiameter\u2014moves at the rate of 68,856 miles every hour, and hence\ncompletes its revolution in its orbit (the Ecliptic) in 365 days and \u00bc.\nThe MOON\u2019s diameter is 2183 miles; she moves with respect to the Earth\n2290 miles in her orbit every hour; and goes round the Earth from change\nto change in 29 days and a half. But having devoted so much of this tract\nto the ph\u00e6nomena of the Earth, as well as its satellite the Moon, we\nproceed to\n\nMARS, known in the heavens by his peculiarly red appearance, arising\nfrom a very thick and dense atmosphere. This Planet is next above the\nEarth, and hence has considerable less light from the Sun than we have;\nis much smaller than the Earth, or about 4470 miles diameter. He is near\n150 millions of miles from the Sun, and goes round him in something less\nthan two of our years, moving at the rate of 55,783 miles every hour. His\nday and night is rather longer than ours, or 24H. 39M. 22S. and uniform\nthroughout his year, so that his axis being perpendicular, he has no\nvariety of seasons. When we pass between the Sun and him he has a most\nfiery and alarming appearance, and is often mistaken for a Comet; but\nwhen we are on the opposite side of our orbit, he appears small, and\nscarcely to be distinguished from a fixed star.\n\nJUPITER, far the largest of our Planets, near 1300 times the size of\nthe Earth, or 93,333 miles diameter, is the next above Mars, at five\ntimes the distance from the Sun that we are; so that he enjoys but a\ntwenty-fifth part of the light, heat, and attraction of that luminary\nwe do.\u2014Though indeed of the light and heat he may still possess, we are\nnot so certain as of the degree of attraction: that being invariably\nproportioned to the distance; while these will be relative to the density\nand other circumstances of the atmosphere, and the aptness of the surface\nof the Planet to acquire and retain heat: after Venus he appears the most\nbrilliant Planet of the Universe. He is attended with four satellites\nthat revolve very regularly round him. The three first are eclipsed\nevery revolution, and every seventh day come in conjunction with him and\none another, as may be seen on the _Eidouranion_. Longitude, at land,\ncan be ascertained by the eclipses of Jupiter\u2019s satellites, as well as\nby a transit of Venus; and these would supercede the necessity of a\ntime-keeper, if they could be observed at sea; hence, in the Nautical\nAlmanack, these eclipses are very exactly calculated for the meridian\nof Greenwich, and answer very good geographical as well as nautical\npurposes. Jupiter is near twelve years in making his way round the Sun,\naltho\u2019 he moves at the rate of 30,193 miles every hour; he turns round\nhis axis in about ten of our hours, so that his days and nights are\nbut five hours each: and he has no variety of seasons; for his axis\nis perpendicular to the plane of his orbit. Turning so swiftly on his\naxis, his figure becomes more oblate than that of the Earth, being more\nthan 6000 miles longer in diameter from one side of his equator to the\nother, than from pole to pole, or in the proportion of 13 to 14.[3] This\nswiftness of his diurnal motion also draws his clouds and vapours into\nstreaks or lines over his equatorial parts, forming what are called\nJupiter\u2019s Belts. An eclipse of the Sun, by this great planet, would be a\nstriking object even to the unassisted sight as viewed from Saturn.\n\nSATURN, 85,782 miles in diameter or about 1000 times as large as the\nEarth, is still a more remote planet from the Sun, round which he\nrevolves in about 30 of our years, at the distance of 916 millions of\nmiles. He moves in his orbit at the rate of 22,298 miles every hour,\nand upon his axis in 10H. 16M. by this swift revolution on his axis his\nfigure becomes oblate in the proportion of 11 to 10, and his atmosphere\nand vapours are drawn like a quintuple belt of 3 darker parts and 2\nlighter upon his body. Saturn is attended by seven Satellites, the\noutermost has been long known to have a period of apparent augmentation\nand diminution, and hence probably to have a revolution on its axis, and\nbe composed of land and water.\n\nA large, broad, double, and luminous _ring_ of 200,157 miles diameter,\nsurrounds Saturn, at a distance from the planet equal to the breadth\nof the ring.\u2014This ring inclines about 30 degrees to the plane of\nthe ecliptic, and must appear like a great arch of light to the\ninhabitants of Saturn. It has a revolution every eleven hours on an axis\nperpendicular to its plane, and keeps parallel to itself at all times;\nhence it disappears twice every 30 years, when its edge is presented to\nus; the Sun shines for near 15 of our years together on the northern\nplane of the ring; and then leaving it, illumines the southern side for\nthe same period; so there is but one day and one night on each side of\nthe ring, but each will be of 15 years continuance without intermission.\n\nThe Sun\u2019s direct light being but about a 90th part so strong to Saturn\nas to the Earth, this ring is no doubt intended to increase it, by\nreflecting a very considerable portion upon the planet, which added to\nthat from his seven Satellites, must render him a very comfortable abode\nfor rational and brute inhabitants.\n\nThe GEORGIUM SIDUS, or Georgian Planet (so called by Dr. Herschell,\nits ingenious and indefatigable discoverer) makes the seventh in the\norder of the system; the other planets we have described have been\nknown as such to the highest antiquity, but from its extreme smallness,\nthis has escaped ascertainment till the year 1781, although it had been\nrecognized as a very minute star by several astronomers. It is near\ntwice Saturn\u2019s distance from the Sun, and will be near eighty-two years\nand six months in going round him; is of a pale colour, and much larger\nin its telescopic appearance than the fixed stars, being 100 times as\nlarge as the Earth, or 37,230 miles diameter, and, on a clear evening,\nis visible to the naked eye. The Dr. has discovered six satellites to\nthis planet, some of which are said to move retrograde. As familiarity\nis the principal design of this Treatise and Lecture, it may be useful\nto exhibit the distances of the planets from the Sun in the most concise\nform, and in numbers they will stand thus:\u2014if the distance from the Sun of\n\n    Mercury\u2014Venus\u2014Earth\u2014Mars\u2014Jupiter\u2014Saturn\u2014Georgium Sidus\n    is 4 will be 7 10    15    52      95        190\n\nor, if a body projected from the Sun should continue to fly at the rate\nof 480 miles per hour, (which is about the swiftness of a cannon-ball),\nit could reach the orbit of Mercury in 9 years, Venus in 16 years, the\nEarth in 23 years, Mars in 34 years, Jupiter in 118 years, Saturn in 216\nyears, and the Georgium Sidus in 432 years.\n\nThese we consider as the regular bodies of our system; so regular,\nindeed, that every ph\u00e6nomenon respecting them is calculated for years\nbefore hand, and it is almost considered as a criminal error to be a\nminute of time wrong in the calculation. But we are sometimes visited by\nCOMETS, which may also be recognized as a part of our system: of these\nour knowledge is very imperfect. By supposing that the same Comet has\nappeared at equal intervals of time; by observing that, like the planets,\nthey describe equal areas in equal times; and by having three points in\nan ellipsis given to make out its eccentricity; from these data it was\nnatural for mathematicians to suppose they could calculate the return of\nall Comets that had been scientifically observed: but the actual return\neven of that conspicuous one expected by Dr. Halley, has been thought by\nsome not to be sufficiently ascertained: yet, on examining the balance\nof probability, as stated by Maupertius, Lalande, Messire and Martin,\nfor its re-appearance, probably this doubt will be greatly lessened, if\nnot removed. As new Comets are almost perpetually appearing, on which\ncalculation hitherto has been silent, there is reason to expect, in a\nproper period of time, an adequate number of observations to decide the\nquestion, whether in general they revolve at stated times, or traverse\nour system without probability of return. Perhaps Comets of each\ndescription time and observation may confirm to us. We know that Comets\naccompanied with tails come very near the Sun, and from all quarters\nof the Heavens! that the tails keep opposite to the Sun; consequently\nthey are only visible to us when seen obliquely to the Sun. Thus the\nComet of August, 1797, was observed to have little or no train during\nany part of its appearance; but a faint hazy light diffused round it;\nthese trains, like electrical and borealean light, do not refract the\nlight of the fixed stars, &c. The appearance of the Comet of 1682, is\ncopied in the _Eidouranion_. It descends from the top of the Machine;\nits train increasing in length and lustre till it arrives at the Sun,\ndiminishing as it ascends. Its orbit is so eccentric that the small part\nof it visible is not sensibly to be distinguished from the parabolic\ncurve; and in this representation it finally disappears in the roof of\nthe Theatre; it being impossible, if its return were ascertained, to\nrepresent the extent of such an orbit, and its motion in it, with any\ndegree of suitable proportion. The velocity of such of these as approach\nnearest to the Sun, particularly of the Comet of 1680, (whose appearance\nwas tremendous) exceeds any swiftness that falls within observation;\nexcept that of the rays of light; it being nearly 2000 times greater\nthan the swiftness of a cannon-ball, at the instant of its discharge;\nyet scarcely a thousandth part of the velocity of light passing from\nthe Sun[4]. This Comet approached to within 40,000 miles of the Sun\u2019s\nsurface, and was calculated to be heated 2000 times hotter than red hot\niron; a globe of iron the size of the Earth in this heat, would be 50,000\nyears in cooling. These amazing visiters, whom philosophy contemplates\nwith awe very different from that terror with which superstition had\nlong viewed them, moving in such amplitude of space, so numerous as they\nare, and so great as some of them, must have functions assigned to them\nproportionally important: either occasionally of terrific revolution;\nor more generally of recruiting the atmosphere of the planets in their\nsuccessive appulse to any of them, and supplying the diminution of the\nsolar fires. Perhaps too they are useful in preventing the central\ntendency of the planets to the Sun, from increasing more than in a\ncertain degree; so that the apparent disturbances, thus produced, will be\npart of the necessary order and harmony of the system.\n\nIt is probable (though their orbits are so much oblique in all\ndirections to those of the planets, that it can rarely happen) that\nComets may be instrumental to great shocks; either by direct collision,\nthe effect of which, considering the velocity and mass of some of them\ncannot be estimated, or by near approach: and of this latter a possible\nresult, and such as seems, in one instance at least, to have already\ntaken place, is noticed in the Remarks annexed to this account of the\n_Eidouranion_. But the philosophic observer will have this reflection\npresented to him from the ph\u00e6nomena of the Universe; that the apparently\ndisturbing and destructive powers are secondary and subservient; while\nthose of the preserving and meliorating kind are primary, continued, and\nuniversal. And those incidental causes of a melancholy and distressing\naspect, when resolved into their ultimate tendency and necessary effects,\nmanifest themselves, in so far as we can trace them, to be parts\nessential to the system of pure and perfect benevolence. Stability and\nduration are stamped on the Universe, and the imagination is lost in\nthe immensity of the prospects; and whether we turn to the past or to\nthe future, our conception vainly pants to grasp the idea of boundless\nEternity.\n\n       *       *       *       *       *\n\nBut when we launch in idea into infinite space, and contemplate\nthe systems without number that fill it; here indeed we have a subject\ntruly worthy of the DEITY! Whoever supposes the fixed stars placed in a\nconcave sphere, as they appear to us, must have a narrow and contracted\nidea of the SUPREME BEING; for one star appears large and another small,\nbecause one is immensely distant from us in comparison of another.\nThrough Dr. Herschell\u2019s large telescope many fixed stars appear double:\nthe Polar star is double; (but they are only stars at different distances\nfrom us appearing nearly in the same line) some appear like a topaz,\nothers azure, others red; all are round, and many as perfectly defined\nas a shilling is on black cloth. By telescopes we formerly could see\nthree times the number we can by the naked eye; and now, telescopes\nhaving received further improvement, in the most crouded part of the\nmilky way, 116,000 have passed before the instrument in a quarter of an\nhour. The Nebula of Andromeda must be composed of the united lustre of\nmany millions of stars. Agreeably to this, Dr. Herschell has noticed\nsingle nebulous stars surrounded with a faint equable whiteness; such as\na system of Planets viewed at that distance from us might be supposed\nto give: others he has seen, which have the appearance of yet unformed\nsystems. And there are, we may presume, points of view, in the immensity\nof the Universe, in which all the fixed stars, accessible to the eye\nor telescope from this station of ours, and all the inconceivable\nspace, through which they extend, vanish into a _nebula_, and almost an\nindiscernible point. Such is the order and greatness of that Empire,\nwhich these Discoveries, the farther they are pursued, must for ever\nmore and more present to our increasing admiration. Such the relation of\nparts so astonishingly remote! Such the unity of intelligence, power,\nand preserving goodness which pervades the whole! And why may not stars\nbe so remote, that their light may not have reached the Earth even since\nthe creation! We know that light takes more time in travelling from\nthe nearest stars to us, than we in making a West India voyage, (which\nis usually performed in six weeks) a sound would not arrive to us from\nthence in 50,000 years, nor a cannon-ball in a much longer time. The\nSun\u2019s light could not therefore reach the fixed stars, and be reflected\nback again with their lustre; of course they shine by their own light\u2014if\nso, they shine as our Sun, and consequently are Suns themselves.\u2014Now,\nas a principal of uniformity runs through the variety of nature, it is\nreasonable to conclude these Suns to be centres of systems like ours;\nand destined for the same noble purposes, viz. that of giving light,\nheat, and vegetation, to various worlds that revolve round them, but\nwhich are too remote for discovery, even with our best telescopes!\nThis idea is infinitely too great for the human mind; or indeed for\nthat of any created Being! For how inadequate must the utmost stretch\nof finite faculties be to represent infinity! The stars, disposed in\nconstellations, and surrounded by concentric circles, may perhaps assist\nthe imagination a little: The attempt in SCENE V. if not admired, we\nhope will be forgiven. But was it possible we could actually take our\nflight into infinite space, or be borne on the wings of lightning, to the\nmost distant fixed Star we can now see, even there, perhaps, we should\nfind ourselves on the confines of creation, and see as many stars before\nus as we left behind! For space has neither top nor bottom in it: it\nis a circle whose centre is every where, but whose circumference is no\nwhere! Even systems themselves may have revolutions round one another;\nand account for that difference of distance that we are constantly\nobserving to arise amongst the fixed stars; for new stars appear, rise\ninto magnitude, and then diminish and disappear, which would also be\naccounted for by supposing that our Sun himself is in progressive motion\ntowards some part of infinite space, and carrying his system of worlds\nalong with him. Stars of the _first_ magnitude, in Flamsted\u2019s time,\ndwindle into those of the _third_ or _fourth_, in our time. Some of\nthe stars change their magnitude periodically: as Algol, in Medusa\u2019s\nHead, which rises from the third magnitude to the second, in two days\nand twenty-one hours.\u2014Where such periodical disappearances are short,\nthey have been referred with probability to quick revolutions of such\nstars on their axis, with part of their disk opaque; or to the regular\nintervention of some very considerable Planet to intercept them from\nus. But re-appearances of this kind, after very long intervals, would\nindicate rather a revolution in a great orbit. By analogy we conclude,\nthat at a proper distance our Sun would dwindle into a fixed Star among\nthe rest, and his system of worlds disappear. Now as we see that almost\nevery particle of our globe swarms with life and animals, we cannot\nsuppose the other bodies of our system to be only intended as a faint\nspangle for mortals to gaze at; more especially as they are as well\ncalculated for inhabitants as ours, revolving as regularly round the same\nSun, and seeming to have every other convenience for rational and brute\ninhabitants[5]. But to carry this idea into infinite space; to recognize\nSuns and Systems, above us, below us, to the East, the West, the North,\nthe South; to consider each Sun as the centre of a system like ours, and\nevery world inhabited!\u2014In short, the astonished fancy turns round, and is\nentirely lost and sunk in the abyss of nature! Well might the Psalmist\nsay, that, \u201cThe heavens declare the glory of God, and the firmament\nsheweth his handy work.\u201d Well might he express himself as overwhelmed\nwith the idea of the power and omnipresence of the Deity; since all our\ndiscoveries serve only to convince us, that a progress of inexpressible\nextent, continued through ages without number, would find us every where,\nas here, surrounded with his infinite energy, eternity, and immensity,\nfilled with his vital presence.\n\n[Illustration]\n\n\n\n\nFOOTNOTES\n\n\n[1] Her mountains by some have been calculated nine miles high; but\nDr. Herschell\u2019s telescopes, which magnify 6500 times, have reduced her\nhighest hills to about _two_ miles. Mr. Shroeter apprehends that the\nmountain _Leibnitz_ is not less than 25,000 feet high. The Craters of the\nMoon are from 4 to 15 miles diameter. He discovers some new spots on the\nMoon, and calculates her atmosphere to be 5376 feet high, an height so\ninconsiderable that it might escape our best telescopes or most minute\nobservations.\n\n[2] It is rather curious how the antients saw so much of him as that\nhis period was tolerably guessed, at least so far back as the days of\nCicero.\u2014_De Nat. Deor. II._ 20. They knew it to be less than the Earth\u2019s:\nwhich, though far from accurate, was a nearer calculation than could be\nthen expected. And this is the more remarkable if Cicero had it from\nPlato, and he from \u00c6gypt and Syria.\n\n[3] If the Earth turned round its axis in 84 minutes and 43 seconds,\nthe centrifugal _force_ would be equal to the power of gravity at the\nequator; and all bodies there would entirely lose their weight. If the\nEarth revolved quicker, they would all fly off and leave it.\n\n[4] The velocity of a cannon-ball is about eight miles per minute.\n\n    Of the Comet in its perihelion    14,600\n    Of Light                      12,000,000\n\n[5] Perhaps the inhabitants of one system may be destined successively\nto pass from planet to planet, and from systems to other systems. This\nwould answer, on an immense scale, to the analogy existing on Earth. It\nis stated as a conjecture with much energy and beauty in a late work.\nIllustrat. of Proph. T. II. p. 557, _Anno_ 1796.\n\n\n\n\nDISSERTATION\n\nON THE PROBABLE CAUSE OF THE\n\nDeluge.\n\n\nSo perfect are the laws by which this wonderful system is regulated, and\nso effectual that Self-physic which the Almighty has instituted through\nall his works, that if any seeming disorder happens in the system, there\nrequires no immediate interposition to prevent or cure the mischief: each\nbody carrying within itself the principles of preservation and cure; an\nargument of wisdom and foresight worthy of the Deity!\n\nThe Planet Jupiter was attracted out of his orbit by the enormous Comet\nwhich appeared in the year 1680. The Comet coming across the plane of\nhis track, had a temporary influence upon him; and it is observable, he\nhas not travelled by the same fixed stars since that period which he did\nbefore it; and no doubt but his usual motion was momentarily retarded,\nand the shape of his orbit altered. Now if Jupiter consists of land and\nwater (and by the spots seen on his face it is more than probable) it is\npossible he might experience a revolution something similar to our flood;\nfor that our flood was occasioned by the near approach of a Comet, is a\nmost natural supposition, and in no wise militates against the scriptural\ndoctrine of that event: it being as easy, and as consistent for the\nAlmighty, to render justice by a secondary cause, as by an immediate\ninterposition. Nor is his attribute of mercy arraigned by the promiscuous\ndestruction the deluge occasioned; for it is evident, by reasoning from\nhis works, that he governs the universe by \u201cgeneral, not by partial laws.\u201d\n\nThe vestiges of the Deluge are so remarkable, both on the surface and\nwithin the bowels of the Earth, that if examined without prejudice, they\nprove, I think, beyond a doubt, that awful revolution to have been the\nwork of a Comet. Not that the moisture of its tail drowned the World,\nas was unphilosophically suggested by Whiston; but if the attraction of\nthe Moon be capable of raising the water of the sea above its common\nlevel, what effects might not be supposed from the near approach of a\nbody perhaps many thousand times larger than the Moon? If a tide by such\nan attraction was raised three or four miles above the level of the Sea,\nthe Earth, by turning on its axis, would have that protuberance dragged\nover the land, and its surface would be plowed up into those inequalities\nwe call mountains; for that mountains are not of eternal duration, is\nevident from their growing less, even in the memory of man. For every\nthing tends to a level. Rains falling on mountains wash down their\nasperities; this matter bemuds the rivers, and banks out the sea; rocks\nthemselves yield up their fantastic forms to the effects of air, water,\nand heat; and land has been growing into the water ever since the Deluge.\nBut why should all assemblages of mountains be arranged like little\nridges of sand on the sea shore? Doubtless by having been produced by a\nsuperior tide, and left to dry by an unreturning sea. Almost all great\nranges of mountains run North and South; the Andes of the Cordelleras;\nthe mountains of the Moon in Africa; the Dophranes, Caucasus, Allegany,\n&c.\u2014the Alps and Pyrenees excepted.\n\nAs Comets visit our system in all directions, why might not that in\nquestion have its motion from North to South, and dragging the sea after\nit, determine the mountains to those points of the compass? Whence\ncome the shells and fish bones we meet with on the tops of the highest\nmountains? We have not discovered any power in nature disposed to work\nsuch quantities of them thro\u2019 the bowels of the Earth; and indeed\nimagination has not yet been so wild as to carry them thither: they are\nnot a fortuitous assemblage of atoms assuming such forms; not _lusus\nnatur\u00e6_, but _bona fide_, shells and fish bones, such as we meet with on\nthe sea shore! We find them also deep buried in the bowels of the ground,\nfar from the sea; we find them in rocks, and often converted into stone:\nnay, may not the fat of fish, joined with vegetable substances, form the\nbitumen of coal? We have experiments that warrant such a suggestion.\nNow if ever the Sea was dragged over the surface of the Earth by the\nattraction of a Comet, these effects must naturally follow.\n\nIn digging into the bowels of the Earth, we have still stronger evidence\nthat the flood was occasioned by the near approach of a Comet. It is well\nascertained, that the united attraction of every atom of the Earth forms\nthat Earth into a dense ball, and not any particular attraction in its\ncentre.\u2014All matter being therefore affected by this power in proportion\nto its density, one might conclude that the heaviest bodies would lie\ndeepest, and the lightest near the surface, but this is by no means the\ncase: Coal is lighter than stone; various minerals lie upon light earths,\n&c. evidently proving, that the general order of nature has at some time\nbeen disturbed, and the manner in which matter obeys the laws of gravity\ndisarranged. Hence the philosophic miner finds strata of various density\nin digging downwards; and in pursuing his vein of ore, finds these\nstrata broken and divided; nay, if he loses the vein, he can easily tell\nwhere to find it again, by the manner in which it broke off. In this he\nnever is mistaken: He sees, as it were, through many fathoms of Earth!\nevidently suggesting, that some revolution on the Earth has broken up its\nnaturally arranged strata, and introduced this \u201cregular confusion.\u201d\n\nThe various strata of the Earth seldom lie on one another horizontally:\nthey generally dip; and near the shore commonly incline towards the\nsea. On the South coast of England, the rocks incline Southerly; on the\nopposite coast of France they incline to the North. Is it not probable,\nthat at the Deluge, the horizontal stratum was broken between these\ncountries: and the ends falling lowest at the breach, formed the channel,\ninto which the sea flowed, when it lost the influence of the Comet,\nand again obeyed the power of gravity? Countries separated by narrow\nchannels, universally have their shores inclining towards the sea;\nshewing that the general geography was at that time altered.\n\nIt is true, we have an old doctrine revived, and supported by\nrespectable authority, that mountains were formed originally by those\neruptions we call volcanos. The votaries of this theory pronounce the\nhollows and cavities on the tops and sides of mountains, Craters, or\nthe cups of extinguished volcanos; and if the stone of the mountain\nbe of a bluish colour, then it is declared Lava; and the proof of a\nvolcano having existed there becomes incontrovertible! History, however,\naffords us very few instances of mountains so formed. Yet this doctrine\nseems to have received very just authority from the last scientific\ncircumnavigators. The rocks which surround the islands of the Pacific\nOcean, generally break off perpendicularly about a mile out at sea, which\nmakes their approach very difficult and dangerous; and as the stratum\nimmediately under the loam of the surface has an ashy, or lava-like\nappearance, the voyagers very naturally concluded, that the immense\nnumber of small islands which stud that extensive ocean, were the product\nof subaqueous eruptions. Still if I might be allowed to hazard an opinion\nagainst such respectable authority, I should rather apprehend that the\nPacific Ocean had been once a continent, and that at the Deluge, when\nthe Earth\u2019s surface was disarranged and broken up by the violent motion\nof the waters, the general body of it sunk beneath the level, or was\nwashed away to other parts, leaving only the more elevated and solid part\nremaining. For volcanos throw up matter piece-meal; islands, therefore,\nformed by them, would have a sloping, or gradually sinking shore: whereas\nthe islands of the Great South Sea are surrounded by perpendicular rocks,\nthat sink in that direction to an almost unfathomable depth in the sea.\nBesides, how can we account for that similarity of manners, customs,\ncolour, and even, language, among the inhabitants of islands so distant,\nthat no mode of navigation they practice could ever make them acquainted,\nor have any communication with one another? If these islands were thrown\nup from the bottom of the sea, their inhabitants would not be thrown up\nwith them, and all with the same custom and language. Now if this immense\npart of the globe was a continent before the Deluge, the inhabitants\nmight be alike; and if the elevated parts were above the subsiding\nwater, (a circumstance more than probable) inhabitants might be saved\nupon them, with every circumstance of similarity we find among them; for\nthat revolution is not of so remote a date, but remains of antediluvian\nmanners might exist at this time.\n\n       *       *       *       *       *\n\n    _Sic undique omni ratione concluditur, mente consilioque\n    divino omnia in hoc mundo ad salutem omnium conservationemque\n    administrari. Quo Spectaculo nihil potest admirabilius esse,\n    nihil pulchrius. Quid tam apertum, tamque perspicuum, c\u00f9m c\u0153lum\n    suspeximus, c\u00e6lestiaque contemplati sumus, qu\u00e0m aliquod esse\n    Numen pr\u00e6stantissim\u00e6 mentis, qua h\u00e6c regantur?_\n\n    CIC. DE NAT. DEOR.\n\n\n\n\n_Heads of Mr. Walker, sen.\u2019s_\n\nLectures,\n\nIN CONDUIT-STREET, HANOVER-SQUARE,\n\nRead every Monday, Wednesday, & Friday, during Winter,\n\nAT ONE,\n\n_On an Explanatory Apparatus_,\n\nThe most extensive and elegant.\n\nONE GUINEA THE COURSE.\n\n\n    I. On the general Properties of Matter, Magnetism, &c.\n\n    II. On the Laws of Motion, Mechanics, Machines of Agriculture,\n    Mills, Cranes, &c.\n\n    III. On the Principles of Chemistry.\n\n    IV. On Pneumatics, or the Weight and Spring of the Air, Musical\n    Vibrations, &c.\n\n    V. On the Gasses and new Discoveries in the Air.\n\n    VI. On the Hydrostatics, or the Motion and Pressure of Water,\n    Canals, Aqueducts, Machines, Ships, &c.\n\n    VII. On Electricity, its Laws, Effects, Circuits, Shocks, &c.\n\n    VIII. Ditto, negative and positive, Lightning, Thunder,\n    Galvanism, Medical Electricity, &c.\n\n    IX. On Optics, Laws of Light, Vision, Lenses, &c.\n\n    X. On the Figure and Motions of the Earth.\n\n    XI. On the Phases, Eclipses, &c. of the Moon, and on the Tides.\n\n    XII. On the Solar System in general, with the new Discoveries.\n\nThis Course may be read privately for 50 Guineas, or to General\nSubscription amounting to 70 Guineas, on application to Mess. Walker,\nsen. or jun.\n\nIpswich: printed by Burrell & Bransby.","title":"An epitome of astronomy, with the new discoveries: including an account of the e\u00eddouran\u00edon, or transparent orrery","tradition":"philosophy-ethics","translated_text":null,"word_count":7923}