38 Lieut. Irwin's Memoir of Afghanistan. [No. 97- 



ceeds the advantage. In Ghaeen, Toorshish, and some other parts 

 of Khoorasan, the highest wells are sometimes 70 yards deep, 

 but in countries better supplied with water, they are much 

 shallower. All the wells are connected below by means of 

 an aqueduct through which water flows to the foot of the hill. 

 Kahrezas are known in almost all parts of Persia and Khoorasan, 

 in the west and middle of Bulochistan, in the country of the 

 Tureens and Bulochees, in the table land of Ghuznee, and 

 even Cabul, but they are not to be found east of that dis- 

 trict. There is at present not one in repair in the whole 

 of Toorkistan, but in the last generation a considerable num- 

 ber were dug by Koobad Khan Undijanee, lord of Koonduz, 

 with a view to the cultivation of hilly wastes called the Dushti 

 Jubulda, but they are now gone to ruin. Very good kahrezas 

 will turn a small mill of the country. The most famous 

 is that in the neighbourhood of Ghuznee, ascribed to Sultan 

 Mahmood. Including its branches it is asserted to be 12 koss, 

 but this is probably an exaggeration. Many kahrezas are 

 two miles long, and in some quarters a great one will cost 

 20,000 rupees. Such works do great honour to those nations, 

 and are one proof out of many of their industrious dispositions. 



170. Wells are proper in level champaign countries and 

 plains, in which water is found throughout at a moderate depth ; 

 natural rills are chiefly useful within hills of considerable height, 

 or at their foot. Kahrezas are natural to a country when the 

 hills are low and unconnected, and consequently send out no 

 constant streams ; but when there are found vallies among 

 such hills, which in the seasons of rain receive the water of 

 the neighbourhood, but are dry during the remainder of the year, 

 it may become advisable to retain that water (to be used 

 when in future most advantageous) by extending a dam across 

 the valley in a convenient situation ; these are the dams most 

 common, and which peculiarly deserve that name. The water of 

 a feeble stream is sometimes dammed up for future use ; and 

 dams are often required in drawing a canal from a river, or 

 diverting the channel of a constant stream ; but such fall under 

 the first species of irrigation. Rain water dams are common in 

 the Soolemanee hills, and in some quarters of Seeweestan. There 



