"Ouch!"
He had held on to it so long he had burned his fingers.
"Never mind," consoled the professor; "that match, Walter, has shown us one important thing."
"And what is that?" asked Ralph.
"That there is an opening to this passage somewhere."
"Why, how——"
"Simple enough. The flame flickered, as Walter held the match up. That shows there must be a draught, and where there is a draught there must be an opening."
"Then, for goodness sake, let's make for it," exclaimed Ralph, stumbling forward in the darkness "I can't stand this blackness much longer."
With his hands spread in front of him the boy started off, the others following. Walter would have lighted another match, but this the professor vetoed. He argued that, not knowing what lay ahead of them, they had better reserve their store for a real emergency. The boys agreed to this readily.
They had gone about two hundred yards when Ralph, whose hands were feeling along the walls as he went, gave a sudden exclamation. Up to this point the passage had been about six feet in height, and four or more in width. Now, however, it contracted until they had to double up, and could only just squeeze through. It grew unendurably hot, too, and as the floor had steadily declined as they went, they argued that they must have reached a considerable depth.