ed craft directly under
her.

"We'll go in by the stern and try to make a quick job of it," Darrin
proposed, as he gave Andrews final instructions, and turned to see that
the signalman with his flag stood well aft on the superstructure.

As the destroyer raced in almost under the dirigible Darrin raised his
right hand. The signalman with the flag did the same.

Just as the "Grigsby's" bridge passed in under the tail of the aircraft
Dave Darrin read the signal for which he had waited. The airmen were
telling him that the bridge of his craft was almost over the bow of the
hidden enemy beneath.

Down came Dave's raised hand. Seeing it fall, the signalman let his flag
drop.

In that same instant the depth bomb was released for its course over the
"Grigsby's" stern.

Almost in the same second there sounded a terrific if muffled report
under the surface. The water rose in three distinct columns, lifting the
stern of the "Grigsby" and almost burying her bow under.

It was as though a great geyser and an earthquake had met. Columns like
waterspouts hurled themselves across and over the reeling destroyer. Even
when the "Grigsby's" nose came out and up once more the destroyer rocked
in the near tidal wave that the swift series of explosions had produced.

"Pardon me, sir," begged Ensign Andrews, when he had regained control of
himself. "I feel constrained to remark, sir, that you appear to know how
to get all the thrills out of life."

"We must have landed right over a mine cargo once more," Dave answered
smiling. "There were several explosions, but they came nearly together.
One of these days we'll start something like that that will send us up
half a mile into the air. But it's great sport, Andrews, especially when
you pause to think what it all means."

"Great sport for us, but too sudden for the Huns," rejoined the watch
officer. "They cannot have had the satisfaction, even, of realizing that
anything had hit them."

Satisfied that there would be no more underseas explosions, Darrin gave
the order to come about.

That the underseas craft had been struck was indicated clearly enough by
the patches of oil on the water. The force of the explosion told the
Yankee tars that the craft must have been blown into bits.

"Best thing I ever saw done!" signalled the British officer in command of
the "blimp."

"Find us another, and we'll try to show you something just as good,"
Darrin caused to be signalled back.

Fern