Night now shut down rapidly. As all on board were intensely weary, they retired early to rest.
Barney was left on guard. The night was black as Erebus.
The Celt sat in the bow of the air-ship where he could easily reach the valve of the searchlight. There was no danger of his sleeping at his post.
As the hours wore on, Barney relaxed his vigilance somewhat. It was past the hour of midnight when an unlooked for thing occurred.
A curious sound came from the distance over the lake.
It was a strange sullen roar and a curious sound like the suction of water through an orifice.
“Begorra, that’s a queer sound,” he muttered. “Phwativer can it be?”
He listened again.
Then he acted upon impulse and turned on the full glare of the searchlight. The pathway of radiance shot out over the lake.
Barney had expected to see the shimmer of the waters.