Any unusually severe exertion precipitated spells of coughing, during which he was almost like a man in a fit.
The blood congested in his eyes till they bulged, while the tears ran down his cheeks.

A whiff of the smoke from frying bacon would start him off for a half-hour's paroxysm, and he kept carefully to windward when Daylight was cooking.
They plodded days upon days and without end over the soft, unpacked snow.

It was hard, monotonous work, with none of the joy and blood-stir that went with flying over hard surface.

Now one man to the fore in the snowshoes, and now the other, it was a case of stubborn, unmitigated plod.

A yard of powdery snow had to be pressed down, and the wide-webbed shoe, under a man's weight, sank a full dozen inches into the soft surface.