His work in the conning tower done, Captain Jack sprang out on the platform deck, bounding beside Lieutenant Danvers at the starboard rail.  Through the manhole opening of, the tower the shipbuilder soon thrust his uncovered head.

Was the torpedo, so carefully aimed, going to strike and do its work?

CHAPTER XVII

THE MESSAGE OF TERROR

“Is it a hit, do you think?” gasped Jack.

“I think—­” began the naval officer.

Boom!  It came suddenly, sullenly.  A column of spray shot up between the two mast-stumps of the derelict.  The rising water reached a height of eighty or ninety feet, then came down again like a heavy rain.

But the wreck itself?

One of the mast-stumps tottered, then the other.  In an instant more nothing of the derelict was to be seen, saving some floating wreckage made up of less water-logged wood.

“A fair hit, I’ll wager my commission!” cried Danvers, eagerly.

“Yes,” nodded Jacob Farnum.  “That’s the last of the derelict.  She’s removed from the paths of navigation.”

There could be no doubt of the completeness of the work done by the torpedo from the “Hastings.”  A broad grin now appeared on the shipbuilder’s lately white face.

“Mr. Farnum, will you tell Hal, whenever he thinks best, to slow down to mere headway?”

“Aye, aye, Captain,” sang the shipbuilder, jovially, and disappeared from view.

“Benson, I congratulate you on your nerve,” spoke Lieutenant Danvers, as he turned, his eyes glowing, to the youthful submarine commander.

“I don’t know as I deserve that good word,” muttered Jack, slowly, shaking his head.  “It was win or die with us.”

“I realize that.”

“And I took a big chance of blowing our engines out.”

“I thought so, at the time.”

“Then, Lieutenant, you must realize that I risked your life, as well as ours.”

“I knew it,” nodded Danvers, coolly.

Then he rested a hand half affectionately on young Benson’s nearer shoulder.

“My boy, what is risking a life or two, when there’s such a prize to win—­such a naval lesson to be learned and taught?  American naval history is full of the names of officers and men who have thrown away their lives in learning something new for the benefit of the service.”

“I like that way of putting it,” replied Captain Jack, though he spoke soberly.  “I had a notion I was pretty wicked when I took such chances.”

“It would have been criminal, if it hadn’t been your purpose to show what a craft of this type can do when pushed in emergencies.  But I have learned much to-day that will stand me in great stead, should I ever be in command of a flotilla of submarines in war time.”

“Then I suppose I ought to forgive myself for my recklessness,” laughed Jack.