If he missed the shack, he might wander about the prairie until he sank down, exhausted; and after a day of fatiguing labor he knew that he could not long face the wind and frost.

There was, however, every sign of a wild storm brewing; it might be several days before he could secure the letters if he turned back, and such a delay was not to be thought of.
He went on, following the ravine where he could trace its course, which was not always possible, until he decided that he must have reached the neighborhood of the farm.

There was, however, nothing to indicate that he had done so.

He could see only a few yards; the snow had all been smooth and unbroken near the hollow, he could distinguish no difference between any one part of it and the rest; and he recognized the risk he took when he turned his back on his last guide and struggled forward into the waste.
Walking became more difficult, the wind was getting stronger, and there was no sign of the shack.

Perhaps he had gone too far to the south.
He inclined to the right, but that brought him to nothing that might serve as a guide; there was only smooth snow and the white haze whirling round him.