h almost a dozen of their own planes speeding through space, a false
move on the part of a careless pilot was apt to bring about a collision
that could have only one result.

Jack made a discovery just then that caused him to cry out.

"The signal, Tom! We are to drop down and give the bombers a better
chance to get there. No matter what the cost, we've got to reach that
bridge to-night!"

Already Tom was changing the course. They had begun to swing lower, each
unit of the attacking squadron in its appointed place. A brief interval
followed, and then came the bursting shrapnel again around them, while
from several quarters close by hovering German planes commenced using
their machine guns, to be answered by the challengers in like manner.

CHAPTER VII

THE BATTLE IN THE AIR

The din soon became general, one after another of the American planes
joining in the battle. The German aircraft held off a little, fighting
from afar, evidently thinking to accomplish their ends without taking too
much risk. Had they boldly assaulted, doubtless the result would have
been much more disastrous to both sides.

The big bombers had but one object in view, which was to bomb the
important target below. To drop an explosive on a certain spot had been
the most important training of those aboard these craft. They had been
carefully selected from the ranks of the many observers taking service
in the aviation branch of the service; and great things were expected
of them now.

The Huns had concentrated the glare of numerous searchlights on the hub
of the squadron's activities, so that the speeding planes could be seen
darting hither and thither like bats during an August evening, darting
around some arc-light in the street.

The flash of the distant guns aboard the planes looked like faint
fire-flies in action. No longer was the earth wrapped in darkness, for
flares dropped by the bombers kept continually on fire. The bridge stood
plainly out, and a keen eye, even without the aid of glasses, could
distinguish the rush of terrorized German troopers trying to get clear of
the danger zone before a well directed bomb struck home.

Jack, leaning from his seat, took all this in. He was keyed to the
top-notch by what he saw and heard. Tame indeed did most other incidents
of the past appear when compared with this most stupendous event.

"Wow!" burst from his lips, as a sudden brilliant flash below told that
the first huge bomb had