"Glad there is no sun," said Jack, "it would be awfully hot down here."
And there the lads spent the afternoon. Darkness came at last, and with its coming, the lads made ready for whatever might occur. Eight o'clock came and there had been no sounds of airships flying above. The lads strained their ears, listening for the slightest sound.
And, shortly after nine o'clock, their efforts were rewarded. Jack suddenly took Frank by the arm.
"Listen!" he exclaimed in a low voice.
CHAPTER VII
AMONG THE ENEMY
To Frank's ears came a distant whirring. To ears less keen than the lad's the sound, which came from above, might have been some bird of the night flapping its wings as it soared overhead. But to Frank and Jack both it meant something entirely different. It was the sound for which they had been waiting. It was an airship.
Through his night glass Jack scanned the clouds and at last he picked up the object for which he sought. Almost directly overhead at that moment, but flying rapidly westward, was a single aeroplane. So high in the air was the machine that it looked a mere speck and Jack was unable to determine from that distance whether it was British or German.
"See it, Jack?" asked Frank in a low voice.
"Yes," was the reply. "A single craft, perhaps half a mile up."