r arose
heavy enough to imperil the floating aircraft. It would be much more
perilous now, under these conditions; but Frank had made up his mind to
attempt the rescue of those in the water, and was not to be easily
daunted.

When the right opening came he allowed the hydroplane to dip gently
down, making sure that there was as little violence as possible in the
drop, because of the chance of burying the forward propeller under; or
losing his balance, upon which so much depended.

Andy knew what he was expected to do, and was nimbly endeavoring to
swing his weight this way or that after they had launched on the waves,
so as to keep the pontoons on an even keel, and prevent a disastrous
spill. For once this occurred, the hydroplane would be of little more
advantage than the wrecked biplane, which barely upheld the two clinging
men, and was evidently sinking lower under the strain, with each passing
second, until the end must be in sight.

At least they had dropped safely. The pontoons had been cleverly
adjusted so as to bear a just proportion of the weight, and they did
their duty faithfully and well in this great crisis.

Of course, the next thing was to try and work closer to the sinking
biplane, and take the men aboard, one at a time. That would be a risky
proceeding, requiring all the skill that Frank could bring to the front.

In the first place he had chosen to drop beyond the wreck of Percy's
biplane. This he had purposely done, in the hope that the wind might
drift them down upon the other aircraft.

A minute's observation convinced Frank, however, that if they waited for
this to happen, the frail support which was buoying Casper Blue and his
mate up would have gone under long long before they could get within
touch.

Already the second man was shrieking for them to hurry, because he could
feel himself slowly but surely sinking; and he let them know that he
could not swim a stroke.

Plainly, then, they must do something to quicken things, if they meant
to be of any service to the two rogues, thus brought to a sudden halt
just when escape had seemed most bright.

Frank remembered his engine. But would it work under such strange
conditions as this? He quickly saw that the rear propeller was half
buried in the water; and if it turned at all would have to churn things
just as though they were in truth a queerly fashioned boat, instead of
an airship, intended to mount to lofty heights, and vie with the eagl