By this time the snow lay to the depth of several inches on the earth. It was still falling, and the cold was increasing. The flakes were slighter, and there were fewer of them. His knowledge of the weather told the rancher that the fall would cease after a while, with a still further lowering of the temperature. Thanks, however, to the thoughtfulness of his wife more than himself, they were so plentifully provided with blankets and extra garments that they were not likely to suffer any inconvenience from that cause. Fortunately for them and greatly to their relief, the stretch of prairie which they had struck continued comparatively level. Occasionally they ascended a slight elevation or rode down a declivity, but in no case for more than two hours was either so steep that the ponies changed their gait from the easy swinging canter to a walk. Once, after riding down a slight decline, they struck another stream, but it was little more than a brook, so strait that a dozen steps brought them out on the other side with little more than the wetting of their animals' hoofs. They rode side by side, for the mare was as fleet and enduring as the horse. Now and then they glanced back, but saw nothing to cause alarm, and hope became stronger than before. "We are doing remarkably well," said the husband, breaking the silence for the first time in a half hour. "Yes," was the thoughtful reply; "we must have travelled a good many miles since the last start, and there is only one danger that troubles me." "What is that?" "The probability--nay, the almost certainty--that we are not journeying toward the fort." "I have thought much of that," replied the husband, giving voice to a misgiving that had disturbed him more than he was willing to admit; "it is as you say, that the chances are against our proceeding in a direct line, but it is equally true that the general course is right." "How can you know that?" "Because we have crossed two streams that were in our path, and they remain behind us." "But," reminded the thoughtful wife, "you forget that those same streams are very winding in their course. If they followed a direct line, we could ask no more proof that we are on the right track." "True, but it cannot be that they take such a course that we are travelling toward the ranch again." "Hardly as bad as that, but if we are riding at right angles in either direction, we shall be in a sad plight when the morning comes. The sun will take from us all chance of dodging the Sioux so narrowly as we have done more than once since leaving home." "We must not forget the peril of which you speak; at such times I trust much to the instinct of the animals." "And would not that, in the present case, lead them to go toward rather than from home?" "I'm blessed if I thought of that!" The rancher was filled with dismay for the moment, and brought Dick down to a walk.