When the hillside was thus exposed, every one was puzzled to observe something dark at the foot of it, which resembled the entrance to a cave.
A strong accumulator for electric light had been brought by Curtis, in case it might be needed, and next day, when the cave had had time to ventilate itself from the outside, Mac, Dr. Wright, and the two boys ventured half-fearfully inside.
Here was a cavern, indeed, and one of immense size. It had never been made by human hands, that was certain. The light was turned on the walls and floor in every direction. All were black and bare, but dry.
The mystery lay in the fact, that on touching the floor it was found to be warm. And yet the rocks around were certainly not igneous.
And there was another mystery; on bending down and applying the ear to the floor, a distinct murmuring sound could be heard.
“If it’s no fire,” said Mac, “it must be steam, and that is the short and the long of it.
“And,” he added, “if we have to stay here for many months mair, what a comfortable bield[F] for baith man and beast this cave will mak.”
But there was still a third mystery, for far away at the other end lay a dark pile, and, on advancing and turning the light on this, Mac, sturdy though he was, staggered back in fear and dread.
“God save us a’!” he cried; “that’s the banes (bones) o’ some awfu’ defunct dragons that must hae roamed the woods and forest here millions and millions of years ago!”
“I think,” said Dr. Wright, “we had better not touch them till Mr. Curtis arrives.”