"Because this is not a torpedo," replied Mr. Henderson. "It is a new submarine boat of my invention, and I was giving it a trial spin."
"I guess you'd better come aboard and do your explaining," went on the captain. "I don't like the looks of things. Lower a boat!" he shouted, "and bring those chaps to my cabin. I want to question them."
It did not suit Professor Henderson to have his plans upset in this fashion. Nor did he care to give a detailed description of his ship to officers of the war department. He had many valuable inventions that were not patented. So he determined to outwit the pompous commander of the cruiser.
The noise made in preparing the small boat for lowering over the side of the big ship could be plainly heard.
"Go below, all of you, and as quietly as you can," whispered Mr. Henderson.
Andy, Mark and Jack obeyed. At that instant the side of the warship was almost deserted, for the sailors who had gathered to observe the Porpoise had gone to lower the small boat.
No sooner had Jack, who was in the rear, disappeared through the manhole than the professor, with a quick jump, followed him.
"Here! Come back!" shouted the warship's captain as he saw Mr. Henderson's head disappearing from view. "Come back I say!"
But with a quick movement the inventor pulled down the manhole cover and clamped it. Then he sprang to the conning tower, and, with a jerk, opened the levers that admitted water to the tanks. The Porpoise began to sink slowly, and then more suddenly, so that, in less than a minute, she was out of sight beneath the waves, and the angry, gold-laced captain was staring in wonderment at the place where the submarine had been. The spot was marked only by a few bubbles and some foam.
"I guess he'll wait some time for an explanation," spoke Mr. Henderson, as he started the big screw and sent the Porpoise ahead at a swift pace.