"It wouldn't be a bad idea to get them in here, and keep hold of the ropes," the other replied; "horses are always more contented if they find themselves near human beings in a storm, so I've heard. So come on, then!"
They were now on their feet. The blackness of the night still held good, only every little while a flash of lightning along the horizon whence the storm was coming dispelled it for a brief interval, when they could see a long distance away.
Just as they started to get the horses Dick noticed that the distant rumbling sound had grown heavier. Suddenly he stood still, and clutched the sleeve of his companion's tunic.
"Roger, perhaps that isn't thunder we hear, after all!" he exclaimed, with a catch in his voice, as though the presence of some new and never before experienced danger influenced him.
"Why, what could it be then?" demanded the other, instantly.
Just then another friendly flash of lightning illuminated the heavens, and for the space of several seconds the prairie was lighted up almost like day. And the two pioneer boys, staring toward the region where the storm seemed brooding, saw a spectacle that chilled their blood, it was so wonderful, so full of tremendous possibilities for evil!
FAR away, it seemed as though the whole surface of the prairie was in motion. To the right and left the boys had seen the same bewildering sight. Roger failed to comprehend what it meant, and turned to his companion for an explanation.
"Buffaloes--one of those great herds we've been told about, and which stretches as far as the eye can reach!" the other replied.
"But will they come this way; and ought we saddle up so as to be ready to make a run for it?" Roger continued; not because he was timid, but that the sight of that endless, heaving mass of moving animals had impressed him strongly.
"Yes, I think we should," Dick replied. "If the storm comes along after them, and starts a stampede, as they call it, we would stand in danger of being trampled under ten thousand hoofs. No one could ever tell what had become of us. So let's roll up our blankets, and get the horses; quick, Roger, because they're heading in our direction, and coming right along."
Indeed, even as they brought the snorting horses in, and started to fasten the loads on their backs, the rumble had increased to a steady roar, so that it seemed to Roger he could actually feel the ground vibrate under the pounding of those myriad of hoofs, as the heavy animals galloped toward the river.