ing to the young and brave.

On and on flew the Allied planes, and the eager eyes of the pilots were
alternately directed toward the earth and then ahead of them, and upward
to discern the first sight of a Hun machine, if such should venture out.

The fliers were now well over the German lines, and the batteries from
below began firing at them. This was to be expected, and Tom, Jack and
the others had gotten used to the bursts of shrapnel all around them.
They could see the puffs of smoke where the shells burst, but they could
hear no sounds.

"The 'Archies' are busy this morning," thought Jack, as he noted the
firing from below, and using the French slang word for the German
anti-aircraft guns.

He took a quick glance toward Tom's machine to make sure his chum, so
far, was all right. Assured on this point Jack looked to his own craft.

"Well," he mused, "at this point the 'flaming onions' can't get us, but
they may pot us as we go down, as we'll have to if we want to get a good
view of the ground where the big gun may be hidden."

The "flaming onions," referred to by Jack, were rockets shot from a
ground mortar. They have a range of about a mile, and when a series of
them are shot upward in the direction of a hostile plane it is no easy
matter for the aviator to pass through this "barrage." Once a "flaming
onion" touches an aeroplane the craft is set on fire, and then, unless a
miracle happens, the aviator falls to his death.

The German gunners, however, could not use these to advantage while the
French planes kept so high up, though the shrapnel was a menace, for
the Hun guns shot far and with excellent aim. A number of the scout
machines were hit, Tom's receiving three bullets through the wings,
while Jack's engine was nicked once or twice, though with no serious
damage.

But as for the German planes they declined the combat that was offered
them. Probably they had different plans in view. It soon became evident
to Tom, Jack and the others that to fly at that height meant discovering
nothing down below. The distance was too great. The big gun might be
hidden almost anywhere below them, but until it was fired, disclosing
its presence by an unusual volume of smoke, it would not be discovered.
Also its fire might be camouflaged by a salvo from a protecting battery.

"It's about time he did that," said Tom to himself at last, as he
noticed Cerfe, who was the leader of the air squadron, dip his plane in
a certa