o report
for duty with others of the brave Americans who, during the neutrality
of this country in the great conflict, went to France as individuals,
some to serve as ambulance drivers, others to become aviators.

The Caudron is the name given to one type of heavy French aeroplane
carrying two or more persons and tons of explosive bombs.

An air raid on the German lines by a fleet of these machines had been
planned. It had been timed for an early hour of the night, but a mist
coming up just as the squadron of heavy machines, each with two men and
a ton or more of explosives, was ready to set out, the hour had been
changed. So it was not until after midnight that the start had been
made.

And now the boys were coming back--that is all who were able to return.
One machine was missing. At least, that was the assumption of Tom and
Jack, for they could count but nine where there should have been ten.
And of the nine one was coming back so slowly as to indicate trouble.

One by one the machines, which ordinarily came back before daybreak,
landed, and the pilot and the observer of each climbed clumsily down
from their cramped seats. They were stiff with cold, in spite of the
fur-lined garments they wore--garments that turned them, for the moment,
into animated Teddy bears, or the likeness of Eskimos.

Their faces were worn and haggard, for the strain of an airship bombing
raid is terrific. But they were quiet and self-possessed as they walked
stiffly across the field to make a report.

"Any luck?" asked Tom, of one he knew; a Frenchman noted for his skill
and daring.

"The best, _mon ami_," he replied with a smile--a weary smile. "We gave
Fritz a dose of bitter medicine last night."

"And he gave us a little in return," sadly added his companion. "Quarre
and Blas--" he shrugged his shoulders, and Tom and Jack knew what it
meant.

They were the men in the missing machine, the Caudron that had not come
back.

"Did you see what happened?" asked Jack.

Picard, to whom Tom had first spoken, answered briefly.

"They caught them full in the glare of a searchlight and let them have
it. We saw them fall. There didn't seem to be any hope."

"But the battery that did the firing--it is no more," added De Porry,
the companion of Picard. "The bombs that Quarre and Blas carried went
down like lead, right on top of the Hun guns. They are no more, those
guns and those who served."

"It was a retributive vengeance," murmured P