CHARACTERISTICS AND DISTRIBUTION OF LAKES 541 
springs where it welled up to the surface was about 38" Fahr., and 
Sven Hedin is of the opinion that the springs assist in keeping the 
waters of the lake cool. 
Rakas-tal, 15,056 feet above sea-level, is very irregular in outline : 
it is 16 miles in length, and the width varies from 4 miles in the 
north to about 13 miles in the south. The lake is very stormy, and 
Sven Hedin was able to take only a few soundings. He found the 
greatest depth in the northern part to be 54 feet, while in the 
south, in the middle of the sound between the island La-che-to and 
the mainland, the depth was 113 feet. 
Lake Hamun.— The Seistan is described by Sir H. M. M'Mahon ^ Seistan 
as a large depression, some 7000 square miles in area and without any 
outlet to the sea, which receives all the drainage of a vast tract of 
country, extending to over 1 25,000 square miles, girt on all sides by 
high mountain ranges. It lies half in Afghanistan and half in Persia, 
and is about midway between the Russian-Turkestan border and the 
Persian Gulf. The Hamun, or lake area, into which the various 
Seistan rivers discharge their surplus waters, lies in the north and 
north-west parts of the depression. In spring and early summer the 
Khash, Tarah Rud, and Harut Rud bring large volumes of water from 
the north, but during a portion of the year their higher waters are 
taken off for irrigation. The Helmund, the principal river of Seistan, 
600 miles in length, rises near Cabul, drains a large portion of 
Afghanistan, and divides into three branches after arriving in Seistan. 
In the flood season the Hamun becomes a vast sea, more than 100 
miles in length, and varying from 5 to 15 miles in breadth. Every 
few years, when the water reaches a certain height, it escapes through 
the Shelag channel into another large and still deeper lake- depression 
called the Gaud-i-Zirreh. When the Hamun water, which is 
singularly free from salt, overflows through the Shelag, the water in 
that channel becomes drinkable ; bat at other times the water found 
throughout its course in large stagnant pools is nearly pure brine, 
with solid salt crystals round the margins. Evaporation is very 
rapid in the region of the Seistan, owing to the heat and the 
strong winds, and as the water of the Gaud-i-Zirreh dries up, a 
thick deposit of salt is left behind. According to T. R. J. Ward, 
Irrigation Officer of the 1903 Mission for the survey and explora- 
tion of Seistan, 10 feet of water is removed by evaporation alone in 
a year. 
The Lake of Bakhtegan (also known as the Lake of Niriz) is 
situated in Ears, a province in the south-west of Persia, bordering on 
the Persian Gulf, and is fed by the Kur and its affluents. 
1 Geogr. Journ., vol. xxviii. p. 209, 1906. 
