"Why didn't I think of it before?" he repeated, his voice shaken with excitement.
"You didn't think of it before, because you were working like a slave. No man can work like that and think of anything but what he is doing. Oh, Allen, won't it be great if you are right?"
"I'm going to see if I am right," he replied.
"How can you tell?" she asked divining that he was fumbling at his pocket.
"In this way," he answered, drawing out the oilskin bag that contained his precious matches.
He struck a match and held it aloft.
At first the flame mounted straight up in the air. Then an instant later it was deflected and stood out at a distinct angle from the stick.
"See," cried Allen jubilantly. "There's a current of air in the cave. It's too slight for us to feel, but the flame feels it. If we were sealed up utterly in the cave, the air would be still. Somewhere the air is coming in from the outside world and it's up to us to find out where."
"Thank God!" murmured Ruth tremulously.
In the sudden transition from despair to hope, they took little account of the difficulties they might have to overcome before they reached that other entrance—or the exit, from their point of view—which they had reason to believe existed. But as their first jubilation subsided somewhat, a soberer view began to thrust itself upon them.