Page:Air Service Boys over the Rhine.djvu/160

150 a series of photographs we can develop them, enlarge them, if necessary, and examine them at our leisure. I had thought of this, but it's a slow plan, and it means—casualties. But I suppose that can't be avoided. But I wanted to try the scouting machines first.

"After all, the taking of photographs from the air of the enemy trenches and the land behind them is a most valuable method of getting information," he continued.

Men, specially trained for such observation work, examine the photographs after the aviators return with the films, and they can tell, by signs that an ordinary person would pass over, whether there is a new battery camouflaged in the vicinity, whether preparations are under way for receiving a large number of troops, or whether a general advance is contemplated. Then measures to oppose this can be started. So, Major de Trouville was right, photography forms a valuable part of the new warfare.

The photographing of the enemy positions is done in big, heavy machines, carrying two men. They must fly comparatively low, and have not much speed, though they are armed, and it takes considerable of an attack to bring them down. But of course the pilot and his observer are in danger, and, to protect them as much as