an unfortunate collision that might result in a fatal disaster.

But every pilot was on edge, and careful to avoid any such blunder. They
had been well drilled in all the maneuvers connected with just such a
hurried ascent in numbers. Each plane had its regular orbit of action,
and must not overstep the bounds on penalty of the commander's
displeasure.

After mounting to the arranged height, the Air Service Boys found that it
was a very animated region, though fully a thousand feet from the earth's
surface. Almost a dozen planes in all were moving in a great circle,
their motors lazily droning, and the pilots ready to enter into squadron
formation on signal.

In fact, Tom and his chum were the last to arrive, which under the
circumstances was not to be wondered at.

"All on deck, I reckon," called out Jack, after he had taken a survey
about him. "There's the signal from the flagship, Tom. We've got to
keep the red lantern ahead of us and fall into line. There go the
bombers to the center, and our place you said was on the left, tailing
the whole bunch."

Like a well disciplined aerial navy they fell into place, each taking its
position as previously arranged. When the formation was made complete
another signal was given. This meant the advance was now to begin, and
the crossing of the German lines undertaken.

Unless there chanced to be some mistake made concerning the proper
altitude required, so as to clear all possible bombardment when over the