Three bells more; and now there was feverish haste. An oval door in the wall ahead was swung open, revealing a round, black hole.
"That is the torpedo tube," said the captain quietly.
The torpedo was moved back three feet, and then again carried forward on its truck so that the end of the torpedo entered the tube.
One bell more. The torpedo moved into the tube, the breech block, which in this case was the oval door, closed, and the crew stood at attention. While thus waiting the boys glanced at the inclinometer and at the direction indicator.
"See it swing back and forth," said Alfred. "It seems to act queerly."
"Not at all," replied the captain. "Evidently we are chasing a ship which is zig-zagging, as we did, for the direction dial is constantly moving."
While thus conversing they were startled by the signal of four bells. One of the men, reaching forward, touched a button, and the signal could be heard in the conning tower. That was, evidently, to inform the commander there that all was in readiness. Everything was expectancy now. The ship still manoeuvered.
Then, without a warning of any kind, there was a singular dull sound, which seemed to shake the submarine from stem to stern.
"They have fired it," said Alfred.
"And they are putting in another one."