of this region is water; and if the natural deficiency of this necessary
fluid can be anyhow supplied, all parts of the plateau will bear crops,
except those which form the actual Salt Desert. In modern, and still
more in ancient times, this fact has been clearly perceived, and an
elaborate system of artifical irrigation, suitable to the peculiar
circumstances of the country, has been very widely established. The
system of _kanats_, as they are called at the present day, aims at
utilizing to the uttermost all the small streams and rills which descend
towards the desert from the surrounding mountains, and at conveying
as far as possible into the plain the spring water, which is the
indispensable condition of cultivation in a country where--except for
a few days in the spring and autumn--rain scarcely ever falls. As the
precious element would rapidly evaporate if exposed to the rays of the
summer sun, the Iranian husbandman carries his conduit underground,
laboriously tunnelling through the stiff argillaceous soil, at a depth
of many feet below the surface. The mode in which he proceeds is as
follows. At intervals along the line of his intended conduit he first
sinks shafts, which he then connects with one another by galleries,
seven or eight feet in height, giving his galleries a slight incline,
so that the water may run down them freely, and continuing them till he
reaches a point where he wishes to bring the water out upon the surface
of the plain. Here and there, at the foot of his shafts, he digs wells,
from which the fluid can readily be raised by means of a bucket and a
windlass; and he thus brings under cultivation a considerable belt of
land along the whole line of the _kanat_, as well as a large tract at
its termination. These conduits, on which the cultivation of the plateau
depends, were established at so remote a date that they were popularly
ascribed to the mythic Semiramis, the supposed wife of Ninus. It is
thought that in ancient times they were longer and more numerous than at
present, when they occur only occasionally, and seldom extend more than