hich man cannot number. Like the Afreets of the Arabian Nights,
they have been mighty slaves, subject to a far mightier master. That
potent magician whose lair is in the centre of the earth, and whom men
have vaguely styled the attraction of gravitation, has summoned them
incessantly toward himself. In their struggle to render him obedience,
they have accomplished results which make all the works of man
insignificant by comparison.

To begin with, vast lakes, which once swept westward from the bases of the
Rocky Mountains, were emptied into the Pacific. Next the draining currents
transformed into rivers, cut their way through the soil which formerly
covered the table-lands and commenced their attrition upon the underlying
continent of sandstone. It was a grinding which never ceased; every pebble
and every bowlder which lay in the way was pressed into the endless labor;
mountains were used up in channelling mountains.

The central magician was insatiable and pitiless; he demanded not only the
waters, but whatever they could bring; he hungered after the earth and all
that covered it. His obedient Afreets toiled on, denuding the plateaux of
their soil, washing it away from every slope and peak, pouring it year by
year into the canons, and whirling it on to the ocean. The rivers, the
brooklets, the springs, and the rains all joined in this eternal robbery.
Little by little an eighth of a continent was stripped of its loam, its
forests, its grasses, its flowers, its vegetation of every species. What
had been a land of fertility became an arid and rocky desert.

Then the minor Afreets perished of the results of their own obedience.
There being no soil, the fountains disappeared; there being no
evaporation, the rains diminished. Deprived of sustenance, nearly all the
shorter streams dried up, and the channels which they had hewn became arid
gullies. Only those rivers continued to exist which drew their waters from
the snowy slopes of the Rocky Mountains or from the spurs and ranges which
intersect the plateaux. The ages may come when these also will cease to
flow, and throughout all this portion of the continent the central
magician will call for his Afreets in vain.

For some time we must attend much to the scenery of the desert thus
created. It has become one of the individuals of our story, and interferes
with the fate of the merely human personages. Thurstane could not long
ignore its magnificent, oppressive, and potent