tween us and it.
But now we know which way to ride. I don't know what town that was,
but they can tell us how to get back to Diamond X ranch."

"It's queer," murmured Nort, as Dick urged his horse in the direction
of the vision they had just beheld.

"What's queer?" asked Dick.

"Seeing that town," his brother went on. "Bud never said anything
about the ranch being so near a place where they had a river steamer.
There isn't a boat of that size on the river around here."

"No," assented Dick. "This must be farther down. Anyhow, let's hit
the trail for there. We aren't lost any more, I reckon."

"Doesn't seem," murmured Nort. But, even as the two brothers urged
their tired, broncos forward, another strange thing happened. In the
very same place where they had seen the vision of the town and the
steamer, only to witness it vanish, there appeared in sharp detail a
large ranch, with its corrals, its bunk house and main buildings.

"There! Look!" cried Dick. "There's Diamond X!"

Nort shaded his eyes with his hands, and peered long and earnestly.

"Diamond X!" he murmured. "That isn't our ranch! Our bunk house isn't
so near the corral, and, besides----"

Then, even as he spoke, this vision vanished as had the other, being
wiped out of sight; fading slowly as if some unseen operator in a movie
booth had cut off his light.

The brothers turned and stared at one another. Suddenly the truth
dawned upon them.

"A _mirage_!" exclaimed Nort.

"That's what!" assented Dick. "Two mirages! We saw one after the
other, a city and a ranch in the same place!"

And that is what the visions had been--mirages, those strange phenomena
of the west--of desert places--natural occurrences in localities where
the air is abnormally clear, and where conditions combine to transpose
distant scenes.

Of course the explanation is simple enough. Of the mirage the
dictionary says it is "an optical illusion arising from an unequal
refraction in the lower strata of the atmosphere, causing images of
remote objects to be seen double, distorted or inverted as if reflected
in a mirror, or to appear as if suspended in the air."

The word comes from a Latin one, meaning "to look at," and that is
about all you can do to a mirage--look at it. It is as unsubstantial
as the air in which it is formed.

There are many varieties of mirages seen in the West, and if the boys
had seen a double one, or had the vision of the city and ranch b