INTRODUCTORY ESSAY. 227 



information of the natives of the country confirms this. We 

 learn from Turner that showers of rain are frequent about 

 Jigatzi during the summer months ; and as the winds in the 

 valley of the Yarn are said to be generally east and south-east, 

 the amount of rain-fall must increase as we descend that river, 

 though, sheltered as it is by the Assam Himalaya and Mishmi 

 mountains, the fall is no doubt comparatively insignificant. 



Of the direction of the mountain-chain to the north of the 

 Yaru nothing is known. The only Europeans who have vi- 

 sited it have been Captain Bogle in 1774, who resided at the 

 monastery of Chammaning, in latitude 30|° north, when on a 

 mission to the Supreme Pontiff; and, more latterly, Messrs. 

 Hue and Gabet, who crossed it on their way from Kokonor 

 to Lhassa. From the accounts of the latter travellers the 

 country seems to be enormously elevated, and continuously so 

 for a belt of many miles in breadth ; and to this may be added 

 the testimony of the Tibetans themselves, and the fact of so 

 many of the greatest rivers of Asia rising within the same 

 area. 



Dr. Hooker collected a few plants on the southern border 

 of Tibet to the north of Sikkim, and these, amounting to only 

 fifteen or twenty species in two days' journey, are almost 

 identical with those from equal elevations (16-18,000 feet) in 

 West Tibet, — a stunted Lonicera and Urtica being the preva- 

 lent species at 16,000 feet, with creeping Carices in the sand, 

 and tufted plants of Alsinece, Draba, Androsace, Oxytropis 

 chiliophylla, Sedum, Saxifraga, and grasses and sedges, most 

 of which ascend to 18,000 feet. The curious genus Thylaco- 

 spermum forms hard, hemispherical mounds on the stony soil 

 at these elevations, and is one of the most conspicuous fea- 

 tures of the flora. The ground was there everywhere covered 

 Avitli an efiiorescence of carbonate of soda, and the pools of 

 water were full of Ranunculus aquatilis and Zannichellia pa- 

 lustris, also typical of similar situations in West Tibet. 



In the valley of the Yaru the Dama {Caragana versicolor) 

 is said to grow, and to be the only firewood; and by the 



