hey had climbed at
rather a steep angle. However, they knew their speed was many times that
of the German machine on a straight course.

On and on they went. Then came a mist which hid the enemy from sight.
The aviators railed at their luck, and Tom and Jack dropped down a bit,
hoping to get through the mist. It lay below them like a great, gray
blanket.

Suddenly they fairly plumped through it, and saw, not far away, the two
big silver shapes, shining in the searchlights which were now giving
good illumination. It was a moonlight night, which seemed a favorite for
a German bombing expedition.

Far below them, and beneath the Zepplins, Tom and Jack could see the
lights of other aeroplanes, which were flying low to observe lanterns on
the ground, set in the shape of arrows, to indicate in which direction
the German craft were traveling. Later, if necessary, these observing
machines could climb aloft and signal to those higher up.

Nearer and nearer Jack and Tom came to one of the Zeppelins. And now, in
the semi-darkness, they became aware that they were being fired at by
a long-range gun on the German craft. The bullets sung about them, but
though their machines were hit several times, as they learned later,
they escaped injury.

Now the battle of the air was on in grim and deadly earnest. Several
scout planes flew at the big Zeppelin like hornets attacking a bear.
They fired their machine guns, and the Germans replied in kind, but with
more terrible effect, for two of the Allied planes were shot down. It
was a sad loss, but it was the fortune of war, or, rather, misfortune,
for the Zeppelin was not engaged in a fair fight, but seeking to bomb an
unfortified city.

Now Tom and Jack, though somewhat separated, were close above the
Zeppelin, and in a position where they could not be fired at. They began
to drop incendiary bombs through the tubes between their knees.

These bombs were fitted with sharp hooks, so that if they touched
the gas bag they would cling fast, and burn until they had ignited the
envelope and the vapor inside. And as they circled about, dropping bomb
after bomb, the two air service boys saw this happen. Some at least of
their bombs reached their target.

The great craft, now on fire in several places, was twisting and turning
like some wounded snake, endeavoring to escape. Tom glanced toward
the other Zeppelin and saw that this was fairly well surrounded by
aeroplanes, but was not, as yet, o