There was much machinery in the submarine There were gasolene motors, since space was too cramped to allow the carrying of coal for boilers.There were dynamos, motors and powerful pumps.Some of these were for air, and some for water.To sink the submarine below the surface large tanks were filled with water.To insure a more sudden descent, deflecting rudders were also used, similar to those on an airship.There were also special air pumps, and one for the powerful gas, which wasmanufactured on board.
Forward from the engine-room was a cabin, where meals could be served, and where the travelers could remain in the daytime.There was also a small cooking galley, or kitchen, there.Back of the engine-room were the sleeping quarters and the storerooms.The submarine was steered from the forward compartment, and here were also levers, wheels and valves that controlled all the machinery, while a number of dials showed in which direction they were going, how deep they were, and at what speed they were moving, as well as what the ocean pressure was.
On top, forward, was a small conning, or observation tower, with auxiliary and steering and controlling apparatus there.This was to be used when the ship was moving along on the surface of the ocean, or merely with the deck awash.There was a small flat deck surrounding the conning tower and this was available when the craft was on the surface.
There was provision made for leaving the ship when it was on the bed of the ocean.When it was desired to do this the occupants put on diving suits, which were provided with portable oxygen tanks.Then they entered a chamber into which water was admitted until it was equal in pressure to that outside.Then a steel door was opened, and they could step out.To re- enter the ship the operation was reversed.This was not a new feature.In fact, many submarines to-day use itAt certain places there were thick bull's-eye windows, by means of which the under-water travelers could look out into the ocean through which they were moving.As a defense against the attacks of submarine monsters there was a steel, pointed ram, like a big harpoon.There were also a bow and a stern electrical gun, of which more will be told later.
In addition to ample sleeping accommodations.there were many conveniences aboard the Advance.Plenty of fresh water could be carried, and there was an apparatus for distilling more from the sea water that surrounded the travelers.Compressed air was carried in large tanks, and oxygen could be made as needed.In short, nothing that could add to the comfort or safety of the travelers had been omitted.There was a powerful crane and windlass, which had been installed when Mr.Swift thought his boat might be bought by the Government.This was to be used for raisingwrecks or recovering objects from the bottom of the ocean.Ample stores and provisions were to be carried and, once the travelers were shut up in the Advance, they could exist for a month below the surface, providing no accident occurred.
All these things Tom and Mr.Sharp thought of as they looked over the ship before turning in for the night.The craft was made immensely strong to withstand powerful pressure at the bottom of the ocean.The submarine could penetrate to a depth of about three miles.Below that it was dangerous to go, as the awful force would crush the plates, powerful as they were.
