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 solid wheels drawn by uncouth animals. The air-boats may be considered as the private carriages of those days, or rather the private yachts, if we regard the relative number of those who possessed them, for they must have been at all times difficult and costly to produce. They were not as a rule built to accommodate many persons. Numbers were constructed for only two, some allowed for six or eight passengers. In the later days when war and strife had brought the Golden Age to an end, battle ships that could navigate the air had to a great extent replaced the battle ships at sea--having naturally proved far more powerful engines of destruction. These were constructed to carry as many as fifty, and in some cases even up to a hundred fighting men.
The material of which the air-boats were constructed was either wood or metal. The earlier ones were built of wood-the boards used being exceedingly thin, but the injection of some substance which did not add materially to the weight, while it gave leather-like toughness, provided the necessary combination of lightness and strength. When metal was used it was generally an alloy--two white-coloured metals and one red one entering into its composition. The resultant was white-coloured, like aluminium {sic}, and even lighter in weight. Over the rough framework of the air-boat was extended a large sheet of this metal, which was then beaten into shape, and electrically welded where necessary. But whether built of metal or wood their outside surface was apparently seamless and perfectly smooth, and they shone in the dark as if coated with luminous paint.
In shape they were boat-like, but they were invariably decked over, for when at full speed it could not have been convenient, even if safe, for any on board to remain on the upper deck. Their propelling and steering gear could be brought into use at either end.
But the all-interesting question is that relating to the power by which they were propelled. In the earlier times it seems to have been personal vril that supplied the motive power--whether used in conjunction with any mechanical contrivance matters not much--but in the later days this was replaced by a force which, though generated in what is to us an unknown manner, operated nevertheless through definite mechanical arrangements. This force, though not yet discovered by science, more nearly approached that which Keely in America used to handle than the electric power used by Maxim. It was in fact of an etheric nature, but though we are no nearer to the solution of this problem, its method of operation can be described. The mechanical arrangements no doubt differed somewhat in different vessels. The following description is taken from an air-boat in which on one occasion three ambassadors from the king who ruled over the northern part of Poseidonis made the journey to the court of the southern kingdom. A strong heavy metal chest which lay in the centre of the boat was the generator. Thence the force flowed through two large flexible tubes to either end of the vessel, as well as through eight subsidiary tubes fixed fore and aft to the bulwarks. These had double openings pointing vertically both up and down. When the journey was about to begin the valves of the eight bulwark tubes which pointed downwards were opened--all the other valves being closed. The current rushing through these impinged on the earth with such force as to drive the boat upwards, while the air itself continued to supply the necessary fulcrum. When a sufficient elevation was reached the flexible tube at that end of the vessel which pointed away from the desired destination, was brought into action, while by the partial closing of the valves the current rushing through the eight vertical tubes was reduced to the small amount required to maintain the elevation reached. The great volume of current, being now directed through the large tube pointing downwards from the stern at an angle of about forty-five degrees, while helping to maintain the elevation, provided also the great motive power to propel the vessel through the air. The steering was accomplished by the discharge of the current through this tube, for the slightest change in its direction at once caused an alteration in the vessel's course. But constant supervision was not required. When a long journey had to be taken the tube could be fixed so as to need no handling till the destination was almost reached. The maximum speed attained was about one hundred miles an hour, the course of flight never being a straight line, but always in the form of long waves, now approaching and now receding from the earth. The elevation at which the vessels travelled was only a few hundred feet--indeed, when high mountains lay in the line of their track it was necessary to change their course and go round them--the more rarefied air no longer supplying the necessary fulcrum. Hills of about one thousand feet were the highest they could cross. The means by which the vessel was brought to a stop on reaching its destination--and this could be done equally well in mid-air--was to give escape to some of the current force through the tube at that end of the boat which pointed towards its destination, and the current impinging on the land or air in front, acted as a drag, while the propelling force behind was gradually reduced by the closing of the valve. The reason has still to be given for the existence of the eight tubes pointing upwards from the bulwarks. This had more especially to do with the aerial warfare. Having so powerful a force at their disposal, the warships naturally directed the current against each other. Now this was apt to destroy the equilibrium of the ship so struck and to turn it upside down--a situation sure to be taken advantage of by the enemy's vessel to make an attack with her ram. There was also the further danger of being precipitated to the ground, unless the shutting and opening of the necessary valves were quickly attended to. In whatever position the vessel might be, the tubes pointing towards the earth were naturally those through which the current should be rushing, while the tubes pointing upwards should be closed. The means by which a vessel turned upside down, might be righted and placed again on a level keel, was accomplished by using the four tubes pointing downwards at one side of the vessel only, while the four at the other side were kept closed.
The Atlanteans had also sea-going vessels which were propelled by some power analogous to that above mentioned, but the current force which was eventually found to be most effective in this case was denser than that used in the air-boats.