"Down below!" shouted a voice.
The boys looked around in surprise, for they had been on deck less than ten minutes.
"Clear the deck!" shouted the same voice. The boys, with the captain, were hustled forward into the conning tower, and the iron door closed with a bang. The boys were permitted to stop only long enough to see two men turn eight swinging bolts, which hung about the margins of the doors, and quickly screw them up against the jamb.
The lieutenant was leaning over a narrow table on which was a chart, and gazing through a crystal-covered port in the front of the conning tower. A bell tinkled, machinery began to turn and impart its vibration to the ship, and it was again a living thing. It glided forward with the same rhythmic noises for a half-hour, and then two bells were heard.
The character of the sounds from the machinery changed; they seemed to move forward with less effort, and as they felt the same inclination in the motion of the ship, all were now satisfied that she was again submerging. Fortunately, they were not confined to their room, and, although no verbal orders had been given for the various operations required to handle the vessel, the prisoners had an opportunity to judge of what was going on.
Thus, when the signal was given to change the motive power from the internal combustion engines to electricity, they could see the engine stop, and an attendant shift the clutch which engaged the electric motors. A dial swinging over a card alongside a pair of levers indicated the direction of movement, while another gave not only the inclination of the ship, but its speed as well.
These things were very fascinating to the boys, but their attention was now attracted to a still more interesting scene. A bell forward gave two short, quick snaps. Four men sprang forward and stood at attention, two on each side of the tube at the right of the hold.
"The indicator shows that the submarine is turning," said the captain. The boys watched the indicator; it had swung around almost half-way.
"There,—look at the inclinometer," said Ralph. "It is moving upward——"
"Ting! ting!" Two more sharp bells forward. The cylinder was off the torpedo, and it lay before them exposed.