"We do nothing unnecessary on the Survey," came the prompt response. "No man knows better than we how much work there is yet to be done." As the days went on Roger found himself becoming quite apt at the pack work, and, to his great delight, found his muscles hardening under the exercise so that the strain was not so great. Several times too, and this gave him great joy, the chief would send him out off the line of march, not more than fifty yards, with instructions to report on the nature of the ground. When about that distance, well within earshot, he was supposed to "Coo-ee" in order to find his way back to the party. It chanced one afternoon, right after the short stop in the middle of the day, that Field sent Roger off, to the right of the party, in quite dense timber, and told him not to go further than twenty-five yards away. For twenty or thirty feet the boy hacked manfully through the underbrush, and then, to his delight, came across a smooth piece of marsh overlaid with water. Testing carefully every step he took, the lad found the bottom of it less like a morass than was the general character of the swamp, and he knew enough to realize that there must be firm ground on the other side. Knowing, moreover, that a piece of information such as this would be of great assistance he ventured to cross the stretch, and as he surmised, found a small hog-back on the further shore of the shallow lake. This ran parallel, so far as he could judge, with the route being taken by the members of the party, and Roger conceived the idea of following along this line, until it would be time for him to rejoin his friends. The wood was thick on the ridge, however, and Roger found that he was not making good time, so after going half a mile or so, he decided to strike across and meet the rest of the party. When Roger turned, however, he found that he had ceased to be opposite the slough, and he plunged into a dense and palpitating quagmire, the kind against which he had been specifically warned, fairly firm on the surface, but which quivered like a jelly as far as he could see when he stepped upon it. None the less, it was the only way the boy knew to rejoin his comrades, so with considerable trepidation he stepped upon the edge. It held him, though with a sort of "give" that was most unpleasant. Another step he took, and this time the quag seemed to resent his intrusion; large black bubbles formed slowly and broke a few inches before his foot and the ground seemed to heave in front of him. The boy realized that he could go no further, but for daring and curiosity he took another step gingerly to see what would happen.