A closing of the switch on wires that led to the instrument outside, and he knew that the container had emptied its contents of water, drawn in the gas and sealed itself.
Then the swift descent.
He flew low as he circled back. They had traveled far on their journey below ground; it was even a longer route where he and Towahg had circled about. But it was the only route he knew; he could take no chances on a short-cut and a possible long-drawn search for the little valley.
He followed the trail. The quick dusk was near; but in an hour's slow flying, while his eyes searched the hills and hollows, the valley was in sight.
He came down slowly in a black sky, with only the soft, muffled roar of the lower exhausts. It was growing dark, and he leaned from an open door to see more clearly his position. All was different from the air, and he needed time and careful scrutiny to get the bearings of the place.
The soft thunder from below was in his ears when a sound pierced through. His own name! And it was Diane's voice calling him in a terrified tone.
"Walter!" she cried. "Help! Help! Oh, Walter, come quickly!"
he scene below was lighted by fitful fires. He was above the upper valley, a hundred yards from their cave: his mind was oriented in an instant, and he knew each foot of ground.