He finally decided upon the latter.
"When the elephant goes on a bridge, he feels of it with his trunk to see whether it is strong enough to bear him, and I'll use my gun to do the same thing." This was no more than a simple precaution, and doubtless saved his life.
Grasping the stock firmly, he reached the muzzle forward, and "punched" the ground pretty thoroughly before venturing upon it, making sure that it was capable of bearing him safely forward into the darkness beyond.
Generally speaking, the ground of the cavern was tolerably even.

There were little irregularities here and there, but none of them were of a nature to interfere with walking, provided one could have enough light to see where he was going.
"If I only had a lantern, I could get round this neighborhood a good deal faster than this," he said.

"It wouldn't be anything more than fun to explore this cave, which may be as big as the mammoth one of Kentucky." Up to this time Fred had been moving almost directly away from the cascade which he had noticed.

The misty light over his head served somewhat as a guide, and he determined not to wander away from that, which would prevent his getting lost in the bowels of the earth.

The boy was quite confident that there was some easy way of getting out of the cave; for if there was none, except by the opening above, then he was in a Bastile, most surely.
It was undoubtedly the cascade which added to this conviction, for it seemed to him more than likely that if the water entered and left the cave, the volume which did so must be of a varying quantity, so that at certain seasons it was capable of carrying a boy with it.