don't intend to try it, do you?" asked the inventor.

"I don't know," confessed Mr. Farnum. "But I'll admit this much--I'm
certainly thinking hard over the scheme that Captain Benson has
proposed."

"It would be unfortunate if we did the thing, and only succeeded in
offending the officers of the Navy," pursued the inventor, an extremely
thoughtful look on his pallid, thin face.

"Oh, of course, as far as the mere expense goes, I'd pay the bill for
the trick," Farnum went on. "To tell the truth. Dave, the point I'm
considering most now is, whether we can really successfully play the
trick that Captain Benson has sprung on us."

"I believe we can; don't believe there'll be any difficulty whatever,"
declared the young captain, his eyes glowing.

"Well, I'm going to think it over a while," announced the builder,
as he finished his meal.

He went directly up to the platform deck, seating himself on a folding
chair. From the loud chuckles that came, from time to time, from the
platform deck, it was plain that the boatbuilder had had his sense of
humor mightily tickled.

Presently, the hail came:

"Benson, come up here, won't you?"

As Jack reported to the builder Farnum stood looking across the bay.

"Captain, how are we going to get at the exact distance between our
boat and the 'Luzon'?"

"It's a question of mathematics, isn't it?" asked Jack, slowly. "Mr.
Pollard is the expert in that line, isn't he?"

"Oh, I say, Dave," bawled the builder down the stairway. "Come up
here, won't you? Now, how far is it from our moorings to those of
the 'Luzon'?"

There being still enough daylight for the purpose, Mr. Pollard brought
up a small transit. Measuring a base-line on the deck of the submarine,
he took two observations, then went below to do some rapid figuring.

"Exactly 1,142 feet, from mooring to mooring," he called up through the
manhole, presently.

"If you've got the distance down as fine as that," laughed back Mr.
Farnum, "good enough!"

"Are you going to try to play Benson's trick, then?" asked the inventor,
reappearing on deck.

"I'm inclined to think," replied the boatbuilder, "that I am. It seems
like too good a thing to miss."

On board the "Pollard" the cabin lights burned late that evening. Once
the plan invented by Captain Jack was explained to the others all hands
turned to, in great glee, to make preparations.

Ships of any size always carry, as a part of the cruising supplies, a