NATUEAL HISTORY OF LAKE TJEMI. 349 



•as follows:— January 43, February 72, March 108, April 133, 

 May 62, June 11, July 0, August 12, September 16, October 38, 

 November 24, December 33 : total 547 millimetres. 



Irrigation and Agriculture. — On the Urmi plateau, whereTer 

 there is water there is agriculture. "Without artificial irrigation 

 the greater part is a sterile waste of gravel, capable of supporting 

 little but thistles, Gentaurea, Gardmcs, Achillea, PyretJirum, and 

 other plants characteristic of the Persian steppes. In spring, 

 the snow has hardly had time to melt away before this steppe- 

 vegetation covers the plains and hillsides with a gseen mantle ; 

 but soon the water in the soil commences to give out, and then 

 the brown-burnt stalks and leaves demonstrate the cessation of 

 vegetable growth. 



The chief objects of the agricultural engineer are first to 

 'Convey water, with as little loss from evaporation as possible, from 

 the valleys near their emergence from the hills to the most fertile 

 soil of the plains, and, secondly, to distribute the water over as 

 great an area as possible. The Persian poets praise King 

 Menucheher as the inventor of the system of subterranean 

 canals which have become so universal in Persia, and which 

 have converted many a wilderness into a fertile plain. Sub- 

 terranean aqueducts or hanats, sometimes many miles in 

 length, which are employed to convey water beneath arid tracts 

 of land, have a double advantage : they not only reduce loss from 

 evaporation to a minimum, but, inasmuch as they are nearer 

 the underground water-level, little of their water is lost by 

 drainage into the ground. It is always curious to note how 

 similar inventions have been independently made in different parts 

 of the world. The ancient Peruvians constructed subterranean 

 watercourses on a noble scale in connection with their gigantic 

 works of irrigation (one traversing the district of Condesuyu 

 measured 400 to 500 miles), and, like the Persians, had laws 

 prescribing the quantity of water which individual landowners 

 might be permitted to draw {Prescott). The waters of the 

 Persian kanats contain the ordinary chub, Capoeta, and Leuciscus 

 of the rivers ; and the dark-vaulted spaces are often the abode of 

 great numbers of bats. 



The chief crops cultivated are cereals, vines, castor-oil, tobacco, 

 melons, rice, and cotton. The fields are so level, and so well 

 trenched, that they can be watered by a simple diversion of an 

 irrigation channel. 



