that it must snap under a severe wrench or
strain, such as commonly comes when a pilot is far afield, and wishes to
execute a necessary whirl.

Jack shivered as he took in the meaning of that partly severed stay. If
it gave way while he was far above the earth it must spell his certain
doom!

CHAPTER VI

LOOKING BACKWARD

"Just see the fiendish cleverness of the fellow who filed that stay!"
Tom cried, as they all stared. "He filled the indentation his sharp file
made with a bit of wax or chewing-gum of the same general color. Why, no
one would ever have noticed the least thing wrong when making the
ordinary examination."

"Then how did you manage to find it, Tom?" asked Jack, breathing hard,
as he pictured to himself the narrow escape he had had.

"I suspected something of the kind might be done; so I ran my thumb-nail
down each wire stay," came the answer. "And it turned out just as I
thought."

"There may be still more places filed in the same way," suggested the
other pilot, looking as black as a thunder-cloud; because such an act
was in his mind the rankest sort of treachery, worthy of only the most
degraded man.

"We will find them if there are," replied Tom, resolutely. "And when
this thing is known I imagine there'll be a general overhauling of all
the machines on the aviation field. One thing is certain, Jack. You were
playing in great luck when you suggested that we ask for a day off and
then picked out this particular one."

Jack shrugged his shoulders as he replied:

"That's right, Tom."

Nothing could be done just then, with night coming on. Tom talked with
several of the attendants at the hangars, and left it to them to go to
work with the coming of morning. He even showed them how cunningly the
work had been carried out; so they might be on their guard against such
a trick from that time forward.

Then the three returned to the villa. Others of the members of the
escadrille were in the car with the trio, so the talk was general,
experiences of the day's happenings being narrated, all told in a
careless fashion, as if those young aviators considered all such risks
as part of the ordinary routine of business.

Later on the news concerning Jack's singular warning, and what came of
it went the rounds. He was asked to show the brief note many times; but
in answer to the questions that came pouring in upon him, Jack could not
say more than he had already said with regard to his suspici