Page:Air Service Boys Over Enemy's Lines.djvu/75

Rh the big fire control machine when Tom's companions dropped down from the "ceiling" to engage them.

Tom watched everything as though photographing the thrilling happenings on his brain forever. He had a greater interest in these things than at any previous period of his life, for was he not also hovering over that observation Caudron, upon which the movements of the advancing French troops depended? At any minute might he not receive the signal from the captain to attack some fresh Boche, who had climbed high above the battle lines to join the general scrimmage, or else "get" the big French machine while its defenders had their hands full with his comrades?

Had Tom been able to use his binoculars just then, which was out of the question of course, and look back to where the monster French guns were firing, he might have noticed various white sheets spread out in fantastic patterns on the ground, the picture varying every little while.

These were used to "talk" with the observer who was sending those messages from the fire-control plane, telling the gunners just how many metres their fire was short, long, to the right, or to the left of their intended objective.

Then again information was being sent by