"It is a trick of the plains," he said. "It almost seems that its only purpose is to torture and mislead thirsty travelers like ourselves."
"But if it isn't a lake," propounded Lige, "what is it? We see it, it is there before us——"
"But don't you notice, my boy, that the trees that appear to surround it are upside down?"
The whole family gazed fixedly at the supposed "lake."
Blue as the heavens, ruffled by the breath of early morning, surrounded by waving trees, it lay tantalizingly before their eyes.
"I have never seen a mirage before," said Mr. Peniman, "but I know that they are a common occurrence on the plains, and in all arid and desert country. They are due to a condition existing in the atmosphere, caused by the reflection of light. What we see over there is probably the reflection of the sky, and as the reflection surface is irregular and constantly varies its position the reflected image will be constantly varying, and is what gives it the appearance of a body of water ruffled by the wind."
For a time the mirage endured, tantalizing them with its beauty, then suddenly faded, the alluring vision disappeared, and its place was filled by the parched grass of the prairies.
It was a bitter disappointment, the more bitter because of the hope it had aroused in their breasts.
Toward evening they saw, outlined against the western sky, two emigrant wagons crawling along over the plains. But so great was the distance, so wide and expressionless the plains that they scarcely seemed to move forward, but to remain stationary against the brazen sky.
There was no sign of shade or water on all the great expanse as the sun went down, and having traveled until twilight had fallen they made their night camp on the dry, barren prairie, with stars and sky and grass their only company.