The axman brought down his blade with his full strength three times, and the fibers of the tree cracked and began to give way. Back over the slowly moving tree came Magee, leaving Bulson alone on the jam. Suddenly the tree parted with a sharp crack and as it did so there arose a grinding roar, and the blocks of ice which had been jammed behind the tree seemed to leap up and fling themselves over the rapid. It did not seem possible that any man could ride that furious clashing of the jam, but Roger noticed that Bulson, making his way to shore over the grinding ice, yet had coolness to stop and give a shove here and a heave there, unlocking the jam, as it were, until, standing on the ice nearest the shore, he gave one last mighty shove and sprang to the bank just as with a seeming disappointed roar the whole jam broke and sped down the foaming river. "That, Mr. Rivers," said the boy, as Bulson quietly threw his impromptu crowbar into the river, "is one of the things I did not learn to do." "Bulson's very good at that sort of thing," was the chief's quiet comment. But the river below the jam was far less kind to the travelers than it had been above. Progress was only possible by careful paddling and short portages. Half the time was spent in the icy water and half on the frozen bank, and though the water was cold beyond belief, and hands and feet were heavy and numb, the sun burned fiercely upon head and shoulders as though it were the height of midsummer, a condition the harder to be borne because it was so early in the season that no one was as yet acclimatized to the heat. It was the most fatiguing day Roger had yet spent on the Survey, not even excepting the famous trip across the Grand Canyon, for in the latter the pace had been his own, while in this he had to play an equal part with exceptionally vigorous and seasoned men, coping with a mountain torrent. The dusk was falling as, once more in boats, and passing through a small gorge, the party reached the confluence of the Jack and Cantwell Rivers. Although the distance traversed had been but twenty-eight miles, and the party had been traveling with the current, so arduous and rough had been the way that eleven hours had been spent in making the journey. After supper Rivers came to Roger and said to him, not with criticism, but in a kindly manner: "Are you tired, Doughty?" The boy would have longed to be able to reply "No," but he knew he could not do so with any pretense at honesty, and so he replied fairly: "Yes, Mr. Rivers, I am a little tired, but I'll soon get toughened up." "Well," said the chief of the party, "I just wanted to let you know that this really has been a hard day, and that no one need be ashamed of feeling tired. We are all conscious of having done a day's work. I thought perhaps you might worry a little at the thought that, if it was to be all like this, you would not be able to keep up. But it won't, and you did well."