Read it through once

Each night the dogs were attended to first. They ate before the drivers ate, and no man sought his sleeping-robe till he had seen to the feet of the dogs he drove. Still, their strength went down. Since the beginning of the winter they had travelled eighteen hundred miles, dragging sleds the whole weary distance; and eighteen hundred miles will tell upon life of the toughest. Buck stood it, keeping his mates up to their work and maintaining discipline, though he, too, was very tired. Billee cried and whimpered regularly in his sleep each night. Joe was sourer than ever, and Sol-leks was unapproachable, blind side or other side.