produced, sir."

"Have soundings taken, Mr. Ormsby," Darrin directed. The depth of the
water was quickly reported. Dave glanced at the sky.

"The light will be strong enough for another hour," he decided. "Have
our two divers prepare to go down at once."

A launch, cleared away with the divers on board, was anchored in the
middle of the oil spot. Two divers went over the side. Presently they
signalled for extra cables. When these were let down they attached pieces
of metal and gave the signal to haul away.

By the time that the hour was up Darrin had abundant evidence to prove
that he had destroyed a mine-layer, and that his bomb had blown up
several mines stored on the craft. This evidence took the form of
fragments of mines.

"Some of these pieces must even have been driven up against our hull,"
Darrin declared. "It is a wonder that we were not sunk."

"The counter pressure of the water would lessen the force of these
fragments, especially after they had been blown out through the shell of
the submarine," Lieutenant Fernald argued. "But I agree with you, sir,
that it's a wonder the 'Grigsby' suffered nothing worse than a shaking."

Other evidence, too, the divers sent up. The destroyed craft had surely
been a mine-laying submarine. The divers measured the length of the
wrecked hull, finding it to be close to three hundred feet. They
reported, too, that scores of German dead lay in the wreckage.

For hours nothing more happened. Just before ten o'clock that night the
mine-sweeper's blinkers signalled a call to the "Grigsby," then about
four miles distant.

"They've found something," Darrin chuckled, when he reached the bridge on
a call from Lieutenant Fernald.

As the "Grigsby" was heading in toward the shoal, and had some minutes
still to go, Darrin asked:

"Mr. Fernald, you had a second and even more thorough inspection of the
hull made, as I directed?"

"Yes, sir; and found the hull so secure that I did not wake you to tell
you, sir. There has been no strain of the plates sufficient to start any
of them."

"I'm thankful to hear that," Darrin acknowledged. "Even with the big,
elastic cushion of water between us and that awful explosion, it seems
almost incredible that we did not wreck ourselves as well as the enemy."

"You've found another submarine?" Dave shouted through the megaphone, as
he rang for slow speed and ran parallel with the waiting snub-nosed
craft.

"We've found two somethings, sir,