IT was a dark night, some two or three hours before dawn, when Air-Mechanic Pearson, one of the outer sentries at the aerodrome near Contalmaison, thought he heard the whirr of propellers somewhere in the dark skies above.
For a few seconds he peered up into the gloomy heavens, trying to locate the sound, for he was very much puzzled, and could not account for the sound on such a night.
"They can't be aeroplanes returning from over the lines," he told himself, "or we should have had notice to light the flares. It will be a sheer impossibility to land without a crash on a dark night like this."
Again he listened, and he thought the droning sound settled down into the throb of engines. He was anxious, however, not to call out the guard on a false alarm, for he had once been severely reprimanded for so doing.
"They cannot be hostile 'planes attempting an early morning raid; it is far too thick. It would be like a nigger trying to find a black cat in a dark cellar," he muttered.
A quarter of a minute later, however, he thought he had discovered the real cause, for the throbbing of aerial engines could now be distinctly heard.
"It's a Zeppelin!" he exclaimed. "They're going to find the aerodrome with their search-light, and bomb the place, then make off before our machines can get up," and he instantly yelled out at the top of his voice, "Turn out, guard!"
The alarm was caught up, passed on to the next sentry, who repeated it, and the next moment, after turning out the main guard, the sergeant came running up, and asked:
"What's the matter, Pearson?"
"Zeppelin approaching from the eastward, sergeant!" replied the air-mechanic.