east as the junction of the forks of the Platte, is one vast
inclined plane.

The Union Pacific Railway winds over these Black Hills at Sherman,--the
lowest point the engineers could find,--and Sherman is over eight
thousand feet above the sea.

From Sherman, eastward, in less than an hour's run the cars go sliding
down with smoking brakes to Cheyenne, a fall of two thousand feet. But
the wagon-road from Cheyenne to Fort Laramie twists and winds among the
ravines and over the divides of this lofty prairie; so that Ralph and
his soldier friends, while riding jauntily over the hard-beaten track
this clear, crisp, sunshiny, breezy morning, were twice as high above
the sea as they would have been at the tiptop of the Catskills and
higher even than had they been at the very summit of Mount Washington.

The air at this height, though rare, is keen and exhilarating, and one
needs no second look at the troopers to see how bright are their eyes
and how nimble and elastic is the pace of their steeds.

The commanding officer, with his adjutant and orderlies and a little
group of staff sergeants, had halted at the crest of one of these ridges
and was looking back at the advancing column. Beside the winding road
was strung a line of wires,--the military telegraph to the border
forts,--and with the exception of those bare poles not a stick of timber
was anywhere in sight.

The whole surface is destitute of bush or tree, but the thick little
bunches of gray-green grass that cover it everywhere are rich with juice
and nutriment. This is the buffalo grass of the Western prairies, and
the moment the horses' heads are released down go their nozzles, and
they are cropping eagerly and gratefully.

Far as the eye can see to the north and east it roams over a rolling,
tumbling surface that seems to have become suddenly petrified. Far to
the south are the snow-shimmering peaks; near at hand, to the west, are
the gloomy gorges and ravines and wide wastes of upland of the Black
Hills of Wyoming; and so clear is the air that they seem but a short
hour's gallop away.

There is something strangely deceptive about the distances in an
atmosphere so rare and clear as this.

A young surgeon was taking his first ride with a cavalry column in the
wide West, and, as he looked back into the valley through which they had
been marching for over half an hour, his face was clouded with an
expression of odd perplexity.

"What's the matter, doctor?"