find it."

"Say, George," exclaimed Bob suddenly, "didn't I hear Mose say that when
the four horses that made this trail turned off the _big_ trail, they
were going at full speed?"

George replied that he did say so.

"How did he know it?" continued Bob.

"By the looks of the tracks and the distance between them. When a horse
is walking his hind foot covers about half the print made by his fore
foot, and the tracks are from two and a half to three feet apart. When
the horse is trotting the tracks are not so distinct, the one made by
the fore foot being nearly covered up, and they are from seven to eight
feet apart. When he is running the print of only one foot can be seen,
as a general thing the ground about the tracks is considerably
disturbed, and they are from seven to twelve feet apart."

If Carey and the rest of the squad did not learn to their entire
satisfaction that they were not out on a picnic this time, the horses on
which they were mounted certainly did, for before an hour had passed
they were very much in need of water--so much so that Bob brought them
down to a trot, and at last to a walk. At the end of another hour their
riders began to suffer in the same way, and it was not long before every
drop in their canteens, warm as it was, had disappeared. Whether it was
the parched appearance of things around them; or the effects of the
wind, which came into their faces as hot as a blast from a furnace; or
the reflection of the sun's rays from the sandhills around them; or the
sand itself, which arose in the air when disturbed by their horses'
hoofs, and settled in their mouths and nostrils,--whether it was one or
all of these causes combined that made them so very thirsty they did not
think to inquire, but certain it was that they would have welcomed the
discovery of a water-course more heartily now than at any other time
during their march. Just how long this state of affairs was to continue
they did not know, for there was not one among them who could tell
whether water was five or twenty miles off. The only thing they could do
was to follow the trail and await the issue of events with all the
patience they could command.

After they had been separated from the main column for about three
hours, two incidents happened which served to relieve the monotony of
the march, and caused them, for the time being, to forget how
uncomfortably hot and dusty and thirsty they were. As they were riding
silently along