Hal was now convinced that they had discovered the object of their search. His first impulse was to run back and inform Dr. Byrd, but a boyish ambition made him hesitate, and that hesitation was perhaps to be blamed for much of the trouble that followed. As he lingered, this thought came to him:
“Wouldn’t it be glorious if we could get behind the waterfall, explore the cave, and come out and report our double discovery to the owner of Lakefarm and all the boys?” The idea was so tempting that he was unable to give it up. The ledge behind the fall was about nine feet from the edge of the flat rocky precipice on which they stood. Now, if he only had a plank nine or ten feet long, he could easily bridge the chasm and walk through the thin spray of water right into this wonderful cave.
Instinctively he looked about him for something that would serve as a bridge, and what was his astonishment to discover the very article he was wishing for. Projecting from a thicket near by was the end of a piece of lumber. He went over and pulled and found it loose. It was a plank twelve inches wide and ten feet long.
“My!” was his exclamation, drowned by the waterfall. “We’re not the first to find this place. Somebody else is using that cave for something and he’s had this plank here to cross over on.”
This certainly seemed to be the natural and only logical explanation of the presence of the heavy piece of lumber in the bushes. At least it would serve the desired purpose, and Hal prepared to thrust it across the chasm so that an end would rest on each ledge of rock.
Frank understood quickly what his companion had in mind and stood ready to help him. The plank was heavy, but Hal was strong, and with a well-calculated effort he placed it in position and kept his balance.
“Now you hold this end while I cross over,” he screamed into Frank’s ear. “But don’t you try to come over.”
Frank nodded eagerly. He had no intention of obeying, but said nothing. He got down on his knees and placed his hands on the plank. There really was no need of this, but it was a natural request for Hal to make, as he would feel safer with a pair of hands steadying the unanchored bridge.
It was now dusk in the cañon and rapidly growing dark. Probably this is one reason why the doings of these two boys were not observed by any of the other members of the searching company. However, the view of most of them was shut off by the high bluffs and rocks near the waterfall and the rest were at a considerable distance away or in hollows or depressions or beyond growths of timber.
Hal stepped onto the plank and moved out over the chasm toward the thin spray and the cave beyond. Meanwhile Frank’s brain was working rapidly. He was thinking of the glory that Hal was winning and he was losing. Why should they not share the glory alike? As soon as his companion reached the cave he also would cross on the plank, walk right through the roaring waterfall and maybe carry back the coveted treasure in his own hands.