of the torpedo was filled with air under high pressure, which drove the motor that ran the propeller of the torpedo. The rudders of the torpedo were kept pointed constantly in a given direction by a gyroscope.
“It is just like a top,” explained our guide, “You pick up a spinning top on the palm of your hand, and watch it stand upright even though you slant your hand this way and that. That ’s how it is with the gyroscope: its axis keeps pointing in one direction, regardless of what goes on about it. To keep the torpedo at a constant depth under water, there is a rudder that is moved in one direction by a spring, and in the other by a plunger upon which the water presses. If the torpedo runs below the set depth, the water pressure will be sufficient to move the plunger up, compressing the spring and elevating the rudder. On the other hand, if it rises above a predetermined level, the water pressure is less, and the spring forces the plunger down, depressing the rudder.
“Our boat is coming to the surface now; we shall be ready to fire soon.”
“Suppose we hit something,” said Will, “before the periscope is out of water?"
“There ts some danger of that, but this craft has ‘ears’ as well as ‘eyes.’”
“Ears?”
“Yes, ears. It's all but human. On each side, there is a diaphragm like that of a telephone. These are connected by wires to a receiver. If any sound is heard, there is a way of telling whether it is louder in one instrument than in the other, and so the captain can determine where the sound is coming from. He always listens for the noise of the propellers of a vessel or the chugging of its engines before rising to the surface.”
At the forward end of the baat, there were four torpedo-tubes, twa of which could be manipulated at a time, Our guide explained that the torpedoes would he placed in the tubes, the breech-blocks closed, and then the cap at the outside opened. The nose of the boat formed the cap. Dy turning a hand-wheel, the cap would be moved out a trifle, letting the water run into the tubes around the torpedoes, and then the cap would he turned on its axis so as to bring two holes in it into register with two of the torpedo-tubes, There was a plate inside which would indicate when the proper registry had been obtained.
The motors had been stopped for an instant, when the order came to unseat the cap and flood the tubes. Instantly, our bow tipped downward, and we lunged forward. Will and I knew there was some danger, by the look on the faces around us. We followed their gaze, and saw the indicator hand racing around to 100, 110, 120, 135 feet. By that time the engine had been started, and the man at the diving rudder-wheel brought us up so smartly that the boat leaped almost clear of the water, betraying us to the “enemy,” of course.
My, how angry the captain was! He kicked up an awful row. Some one had blundered. There were no torpedoes in the tubes when the order 
The crowded quarters of a submarine. to flood them was carried out. The nose of our submarine was suddenly loaded with several tons of water. Naturally we had gone down like a shot.
