esiring to
scrutinize a special sector of terrain in No-Man's-Land, the disputed
region lying between the hostile trenches.

Jack used his eyes to advantage. These things had not yet grown stale
with him, for he still found himself filled with awe and wonder when
gazing down from a lofty height at the world shrouded in darkness below.

There within a comparatively short distance, that might not be over
twenty miles, a round million of soldiers were gathered, armed with
numberless engines of destruction of the most ponderous nature
imaginable. It was enough to give any one a genuine thrill, and Jack
felt such a sensation creeping over him.

The crucial time had now come. They were passing over the line of the
French trenches. Jack knew this from various signs, and also that in
another minute they might expect to be spotted by some of the enemy
searchlights. These would be unmasked, and trained on the heavens in the
effort to locate the cause of that well known clattering noise above.

This speedily came about. First one long shaft of dazzling light rushed
back and forth; then others joined in the hunt, until presently they
focussed on the progressing two-seater pushing north.

Then began the bombardment. Numerous anti-aircraft guns were poking
their noses upward in anticipation of just such a call. Their crews
commenced to shower the shrapnel around and below the bird of passage,
whose mission, whatever it might prove to be, could mean only evil to
the Teuton cause.

All this racket was lost upon the two so far above the earth. They heard
nothing of the bleat of the firing guns. Even the bursting of shrapnel
went unheeded, save at a time when a shell exploded close by, and was
faintly heard.

Tom was wisely taking but little chance. He maintained an altitude that
prevented most of the shrapnel from coming anywhere near the plane.

They crossed the enemy front, and sped on. The bombardment diminished in
fury as they left the first and second line trenches behind them. It was
continued to some extent from an elevation further back, but as Tom knew
of this formation, and had crept up still higher, no accident happened
to them.

At last the air service boys were fully launched on their night voyage
through the upper currents. Tom waited until he considered that it was
really safe to change their course. He did not want to betray his
movements in case some daring Boche pilot started up in a swift Fokker
machine to