He learned! As the foot touched the ground it sank even with the little weight that he threw on it, almost to the depth of an inch, and with that slight pressure suddenly the suction of the marsh gripped him as though some foul fiend had him by the heel, and he threw all his weight back on his left foot in an endeavor to pull out the right. But this disturbed the balance of his poise, and the sudden weight on the one foot caused it to break through and the marsh had him by both feet. The pressure was so fearful that Roger knew shouting was useless, he would be deep under the quagmire before his comrades could even begin to find him. But Field had not instructed Roger for nothing, and the lad was quick of thought. Instantly he threw his surveyor's rod down so that one end was on the comparatively dry ground whence he had stepped, the other by his feet, and with one supreme effort he threw himself flat upon the rod, though wrenching his ankle cruelly as he did so. This distribution of his weight over so much larger a plane surface prevented his further sinking, but the suction was still so great that he could not draw out his feet. Finally, by exerting all his strength he freed the one that was furthest out, and which had sunk but little, but he was held a prisoner by the other foot. Then an idea occurred to him. Taking his ax, he chopped the ground around his leg, and had the satisfaction of seeing water bubble up in its place. Little by little he loosened the suction of the bog until at last he was able to pull out his foot and crawl along the rod to the bank, where, trembling and exhausted, and suffering considerable pain from his wrenched ankle, he sat upon a projecting root to recover his breath and his somewhat shaken nerve. This was Roger's first experience of the folly of attempting more than he had been told to do, before he was an old enough hand at the game to know the greatness of the risk. As soon as he had in part recovered himself, he shouted, according to agreement, expecting to hear immediately the return hail, which would tell him exactly where the party might be. But there was no answering cry! A little startled at the thought that he might have wandered out of hearing of the party, Roger waited a moment, then, making a megaphone of his hands, let out a stentorian howl, for all that he was worth. But the cry fell stifled in the dense branches and a muffled echo was the only response. Thinking that perhaps a whistle would sound further, he put his fingers in his mouth and whistled long and shrill, a note loud enough, it seemed to him, to be heard for miles; but for all the token of human answer, it might have been the crying of the curlew above the marsh.