"Don't you do it, old fellow--don't you dare!" ordered Hal, sitting up
straighter and resting an appealing hand on his chum's shoulder.

"But think of the lives that have been lost on submarine boats during the
last few years," pleaded Jack Benson, seriously.

"And you want to add your life to the others," retorted Hal, with mocking
irony.

"I want to save, perhaps, hundreds of lives in the future," returned Jack,
spiritedly.

"Then, at least, old chum," begged Hal, "tell your scheme to Mr. Farnum,
and let him hire a trained diver to make the experiment."

"You think there's a lot of danger in it, do you?" queried Captain Jack,
mildly.

"I certainly do," said Hastings, with emphasis.

"Then I'll do the trick myself," contended Jack. "I'm not going to think
up a trick too dangerous for myself, and then hire another man to take
all the risk for me."

Hal said no more. He knew the folly of trying to persuade his chum out
of a decision like the present one.

"I don't believe Farnum will let you try it," hinted Eph. "It sounds too
dangerous."