Sick Heart River by John Buchan — Read

The trail led away from the lake shore up a tributary stream towards what looked like the main wall of the divide. The berry- clad, ferny hillside made easy walking, and since the timber was small there were few troublesome windfalls. Johnny carried his .44 rifle, his axe, and a bag containing his own personal effects and most of Leithen's; the Hares, Big Klaus and Little Klaus, had the heavy stuff, tent, cooking utensils, portable stove, stores; while Leithen had no more than a light haversack about the weight which he had often carried in the Alps. The pattern of his day was now so familiar that he found it hard to fit into it the astounding novelties in his life -- his quest for a man whom he had never seen, in the least-known corner of North America -- the fact that presently somewhere in this wilderness he must die.

New also in his experience were the weather and his own weakness. The sun was getting low and the days were shortening; each night frost crisped the edges of the streams, and the first hour of the morning march was through crackling pools and frozen herbage. But by noon the sun was warm and it set daily over their left shoulders in a haze of opal and pearl. The morning and evening chills were keenly felt, but the tonic air seemed to soothe his coughing. It was the very quintessence of air, quickening every sense so that he smelt more keenly, heard more clearly, saw things in sharper outline. He had never used spectacles, and he found that his eyes were fully the equal of Johnny's when he knew what to look for.