"Well, we can't live without air, you know. It seems to be fairly fresh now, but how long it will continue that way there is no knowing. I'll examine the barrier, but keep back out of the way while I am doing so."
The young engineer climbed over the heap of broken rock in front of him, and made a careful inspection of the cave-in that had so effectually imprisoned them in the drift.
He found nothing to encourage him. The condition of the collapse was even worse than he had anticipated.
"Can you pace—measure off by taking a series of long steps?" he asked.
"Yes," replied Tad promptly.
"Then please go back to where the bend in the cut begins, and pace down to where I am."
Tad did so promptly, glad to be able to do something to occupy himself as well as to help relieve the tension for the others.
"Exactly forty paces," he informed Mr. Phipps.
"One hundred and twenty feet, eh?" The engineer made a brief calculation in his mind. "One hundred and twenty feet. H-m-m-m."
"Is it as bad as you thought?" questioned Tad.