“Let’s wait for it,” proposed Jack.  “It will be along in a moment.”

We waited and listened.  Then we distinctly heard the whistle of a locomotive, and the faint roar gradually ceased.

“It’s stopped somewhere,” I said.

“Don’t see what it should stop around here for,” said Jack, “unless to take on a sand-hill crane.”

Then we heard it start up, run a short distance, and again stop; this it repeated half a dozen times, and then after a pause it settled down to a long steady roar again.

“It isn’t possible, is it, that that train has been stopped at the next station west of here?” I said.

“The next station is Cody, and it’s a dozen miles from here,” answered Jack.  “It doesn’t seem as if we could hear it so far, but we’ll time it and see.”

He looked at his watch and we waited.  For a long time the roar kept up, occasionally dying away as the train probably went through a deep cut or behind a hill.  It gradually increased in volume, till at last it seemed as if the train must certainly be within a hundred yards.  Still it did not appear, and the sound grew louder and louder.  But at the end of thirty-five minutes it came around the curve in sight and thundered by, a long freight train, and making more noise, it seemed, that any train ever made before.

“That’s where it was!” exclaimed Jack—­“at Cody, twelve miles from here; and we first heard it I don’t know how far beyond.  If I ever go into the telephone business I’ll keep away from the Sand Hills.  A man here ought to be able to hold a pleasant chat with a neighbor two miles off, and by speaking up loud ask the postmaster ten miles away if there is any mail for him.”

We were off ploughing through the sand again early the next morning.  We could not give the horses quite all the water they wanted, but we did the best we could.  We were in the heart of the hills all day.  There were simply thousands of the great sand drifts in every direction.  Buffalo bones half buried were becoming numerous.  We saw several coyotes, or prairie wolves, skulking about, but we shot at them without success.  We got water at Cody, and pressed on.  In the afternoon we sighted some antelope looking cautiously over the crest of a sand billow.  Ollie mounted the pony and I took my rifle, and we went after them, while Jack kept on with the wagon.  They retreated, and we followed them a mile or more back from the trail, winding among the drifts and attempting to get near enough for a shot.  But they were too wary for us.  At last we mounted a hill rather higher than the rest, and saw them scampering away a mile or more to the northwest.  We were surprised more by something which we saw still on beyond them, and that was a little pond of water deep down between two great ridges of sand.

“I didn’t expect to see a lake in this country,” said Ollie.

I studied the lay of the land a moment, and said:  “I think it’s simply a place where the wind has scooped out the sand down below the water-line and it has filled up.  The wind has dug a well, that’s all.  You know the telegraph-operator at Georgia told us the wells here were shallow—­that there’s plenty of water down a short distance.”