Still Media, though deficient in natural products, is not ill adapted for cultivation.  The Zagros valleys and hillsides produce under a very rude system of agriculture, besides the fruits already noticed, rice, wheat, barley, millet, sesame, Indian corn, cotton, tobacco, mulberries, cucumbers, melons, pumpkins, and the castor-oilplant.  In Azerbijan the soil is almost all cultivable, and if ploughed and sown will bring good crops of the ordinary kinds of grain.  Even on the side of the desert, where Nature has shown herself most niggardly, and may seem perhaps to deserve the reproach of Cicero, that she behaves as a step mother to a man rather than as a mother, a certain amount of care and scientific labor may render considerable tracts fairly productive.  The only want 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 a few miles from the base of the hills.