On their third day's journey inland they found that which altered all the course of their wanderings, and led them on to great new things. They crossed the trail of the unknown.
Swiftly the seven gray coursers of the snows were speeding, noses down and plumed tails awave in the breeze of their going. The girl sat on the sledge, and beside it the man raced, light of foot as the dogs, and never tiring.
Then, in the midst of his stride, Marcus, the leader, set his four feet hard on the snow crust and slid on his hams, the six others piling up at his back in confusion with sharp yelps of consternation. Over the tangle of the pack whined and cracked the long whip of Polaris, and cracked and whined vainly. Marcus would not budge. He lifted his gray muzzle in a weird howl of protest and bewilderment, and the hair along his spine bristled.
Behind him Octavius, Julius, Nero, and Hector took up the cry of astonishment, and the mellower notes of Pallas and Juno chimed in.
Polaris straightened out, like the good driver that he was, the sad kinks in the harness and ran forward; but he had gone but a few paces when he, too, stopped in the snow, and stood staring ahead and down.
They were at the brink of a trail!
There it lay, stretching from somewhere near the base of the mountains, away across the great plains—a broad, recently traveled path, with footprints plain upon the snow—the footprints of men!