If the system of water supply in the "City of the Golden Gates" was wonderful, the Atlantean methods of locomotion must be recognised as still more marvellous, for the air-ship or flying-machine which Keely in America, and Maxim in this country are now attempting to produce, was then a realised fact. It was not at any time a common means of transport. The slaves, the servants, and the masses who laboured with their hands, had to trudge along the country tracks, or travel in rude carts with…