Both the others surveyed the spot with considerable interest. The rock formation was peculiar in many ways. It looked as though at some remote period, when the continent was in process of formation, upheavals had forced numerous minor ridges of stone to assume the shape of "hogbacks," as Mayhew called them. It was toward one of these that Dick now pointed. Looking closely, Roger fancied he could just detect what looked like a dark spot near its base. He knew then that Dick must have noted some other land-mark in order to find the place. No doubt the habit of observation which the young pioneer cultivated, much as modern Boy Scouts are taught to do in these days, had come in handy again, as he had often known it to do in the past. They pushed closer. There was an opening without any doubt. Just what it led to, of course none of them could more than guess; but they had hopes. "One thing let us notice," ventured Roger. "Here is a dead tree, and if we find it possible to build a fire inside we know where to come for fuel." "Good for you, Roger," the other lad hastened to say. "And now to try and find out what awaits us here." Dick insisted on being the leader. The discovery had been all his, and it was therefore up to him to be the guide. On hands and knees Dick crept carefully into the hole. He held his gun in such a way that if it became necessary he could make quick use of it. So far as he knew there was no peril hanging over their heads; but it always pays to be ready. Their progress was very slow, because they had to grope their way along. Dick put out a hand and felt of the rock before trusting himself to advance. He had no desire to find himself whirling through space, after the manner of their lost packs, in case an unseen abyss yawned in front of him. This went on for several minutes. They had pushed some little distance into the gaping aperture, and so far as could be ascertained there was as yet no limit to the cave. Dick arrived at the conclusion that they had gone far enough to admit of a change in their method of procedure. "I am going to strike a light, so keep still, please, both of you," he announced. Dick was always prepared for anything like this. His tinder, flint and steel were handy, and he even had a small piece of tallow dip that hardly deserved the name of candle, but which had a wick, and would give out a faint glow if ignited. To the boy of to-day this awkward means of producing a light would have presented almost insurmountable difficulties, and ultimate success might well be hailed as a wonderful feat. To the pioneer lads it was of such daily occurrence that they thought nothing of accomplishing it. In a very brief period of time Dick had clipped his flint and steel together so as to send a shower of sparks into the tiny bit of inflammable tinder, which began to smolder. This was blown until it flamed up, when the wick of his tallow candle-end was thrust into the blaze.