Then to make a change, a long rapid would appear, and the only way to negotiate it was to lift the canoes shoulder-high, all the party together under the one canoe, and climb up that rapid with the ice water perhaps up to the waist, and a cruel, drenching spray whipping into their faces. In the meantime, if the mosquito veils were thrown back--and few things are more uncomfortable than a wet mosquito veil flopping about the face, why, then those torturing pests got in a full day's work; the while that a hot Alaskan summer sun blazed above them and blistered face, arms, and neck, exposed alternately to vivid sun and icy spray. On July 5th, the spruce, which had thinned out rapidly during the couple of days preceding, came to a sudden end, the northern limit of timber having been reached. Nothing seemed to impress on Roger so clearly the fact that he was now in the Arctic Circle as the thought that he was in a climate so rigorous and gale-swept in winter that no tree could grow. A few stunted willow bushes, here and there, still remained, when sheltered on the bank of the river, but trees, as such, worthy of the name, there were none of any sort whatever. "I never realized," said Roger, "that there was no timber of any kind in the far north. What do the Eskimos burn for fuel?" "Have you ever seen pictures of stoves or fireplaces in the Eskimo snow hut?" was the answer. "They depend on the heat of their own bodies in a hut without any ventilation, on the flame of blubber lamps, and occasionally, on a little driftwood which may have come down into the Arctic Ocean from some immense stream like the Mackenzie, which, flowing thousands of miles, has passed in its upper reaches through a timbered country." But by the time that the boy had reached this northern limit of spruce he had lost all idea of time. The days and nights seemed one perpetual nightmare. When asleep he dreamed that he was wading, or tracking, or poling, and when awake he felt as though he were working in his sleep. It seemed to him that he had spent years and years on an icy river, and that fate had tied him to it for ever and ever. By the time that two full weeks of it had passed by, the boy no longer had any thought of reaching the summit, that this toil could stop was a thought incredible, and though his muscles, stiffened and well-trained, continued to do their full man's share of the work, the mental strain was intense. Rivers and Gersup were considerably troubled over the fact that the boy's strength showed no signs of giving way, and they would almost rather have seen him break down physically than continue his work doggedly, yet like a machine. It became hard, toward the end of the trip, to make him answer a question, and it would have to be repeated several times before the boy could grasp it. Orders regarding the work he seemed to understand at once, but other matters fell on deafened ears.