Page:Jack Heaton, Wireless Operator (Collins, 1919).djvu/225

 work it. This was done so that in case a man was put out of action another could take his place. It didn’t take me very long to get hep to all the tricks for I already knew the A B C of oil engines, which again came in handy; storage batteries were right in my line and the rest of the machinery was pie for me.

The H-24 has a hull that is very much like a huge catfish, that is it has a blunt round head and the torpedo tubes, one on either side, look for all the world like a pair of great eyes; the body tapers off gracefully to a point at the tail and on this the direction rudder is attached. Two horizontal rudders, or hydroplanes as they are called, by which the submarine is given its diving angle, are fastened one to each side of her head and give the appearance of a pair of great lateral fins.

Her hull is built up of thin but exceedingly strong sheets of steel and these are riveted together in the same fashion as the hull of any steel ship. When you consider that the hull of a submarine must be able to stand a pressure of at least 200 pounds to the square inch—as much as a high pressure steam boiler—without collapsing when it is fully submerged it must