ignal and as he headed straight for the spot
over the fortress he gave Jack the sign. The bomb slipped from its
sheath, and was instantly lost to sight in the smoky atmosphere below.

Already they had had their ears shocked by numerous discharges, as
others among the Americans shot their missile earthward. It was terrible
to look down at that crisis in the attack. The whole world seemed on
fire beneath them, what with the exploding bombs and the myriad flashes
coming from the German guns at work.

Jack was disappointed because in this vast inferno he found it utterly
impossible to tell where his special messenger struck. He knew, though,
that he had been in a fair position for a hit when given the word, and
on that account never found any reason to doubt but that it had given a
good account of itself.

After delivering his fire Tom swept off to one side so as not to
interfere with another bomber who might occupy a higher level, and be
advancing to the attack.

Presently when the turn of the air service boys came again they would be
ready to send down the second "bundle of concentrated destructiveness";
and later on there might be a "clean-up call" that would exhaust the
stock carried by each plane.

Meanwhile, given a chance to look hastily around at other factors
connected with the extensive engagement, Tom discovered that there had
been at least one victim besides the initial one.

A plane was dropping swiftly, swinging this way and that, turning over
and over, and showing signs that the pilot's hand no longer controlled
the levers. He was unable to make out whether it was an enemy plane or
one of their own convoy; but the doom of those who happened to be belted
to the seats was undoubtedly sealed.

CHAPTER XVIII

FAVORED BY FORTUNE

THE Huns soon discovered that they were up against an intrepid enemy.
When they so boldly attacked the Yankee fleet of raiders, as Jack
expressed it in his boyish way, they had "bitten off more than they
could chew."

They had dropped back a bit and were trying to annoy the Americans all
they could with as little damage to themselves as possible. If their
last stronghold was doomed to destruction under that rain of mighty
bombs, any self-sacrifice on their part could not ward it off, and so
what was the use?

The end seemed to be approaching, for the Boche plainly showed he had
had enough of the fighting. One last combined attack all along the line
that would likely