200 REVIEWS. 



He notices the strange diurnal variations of depth which occur in the 

 river at Rampoor, which he attributes to the " variable amount of solar 

 action on the snows by which it is fed. This effect Major Cunningham 

 had noticed on his former visit to the mountains, and had frequent 

 opportunities of observing it during his journey. At Rampoor the diurnal 

 variation was not less than three or four feet, the maximum being, I 

 believe, during the night or only in the morning. In the immediate vicinity 

 of snow, the streams are highest in the afternoon; but as the distance 

 increases, the period of greatest height becomes by degrees later and 

 later." 



Dr. Thompson well describes several Glaciers, some of them of great 

 extent, and his book is thus of special interest to geologists ; he also shows 

 evidence of Glacier action to a lower level than at present is reached by it ; 

 and proof of plasticity in the spreading terminations of existing Glaciers. 



Our author also visited the Borax plain at Pugha, which he thus 

 notices : — 



u The whole of the plain is covered, to the depth of several feet at least, with 

 white salt, principally borax, which is obtained, in a tolerably pure state, by dig- 

 ging ; the superficial layer, which contains a little mixture of other saline matters, 

 being rejected. There is at present little export of borax from Pugha — the demand 

 for the sale in Upper India being very limited, and the export to Europe almost 

 at an end. 



u It has long been known that borax is produced, naturally, in different parts of 

 Tibet ; and the salt imported thence into India was at one time the principal 

 source of supply of the European market. I am not aware that any of the places 

 in which the borax is met with had previously been visited by any European 

 traveller ; but the nature of the localities in which it occurs has been the subject of 

 frequent inquiry, and several more or less detailed accounts have been made 

 public. 



" These differ considerably from one another ; and no description I have met 

 with accords with that of the Pugha Valley. Mr. Saunders describes (from hear- 

 say) the borax lake, north of Jigatzi, as twenty miles in circumference ; and says 

 that the borax is dug from its margins, the deeper and more central parts produc- 

 ing common salt. From the account of Mr. Blane, who describes, from the infor- 

 mation of the natives, the borax district, north of Lucknow — and, therefore, in the 

 more Avestern part of the course of the Samper — it would appear that the lake 

 there contains borax acid, and that the borax is artificially prepared, by saturating 

 the sesquicarbonate of soda, which is so universally produced on the surface of 

 Tibet with the acid. At least the statement, that the production of borax is de- 

 pendant on the amount of soda, leads to this conclusion. ' 



Scattered through this book are occasional observations interesting to the 

 zoologist — such as the occurrence of the Kiang, or wild horse, at an eleva- 

 tion of 15,000 feet ; and of fishes at the same great height. 



On the whole, though the book is one not likely to be used to while 

 away the hour, it possesses much to interest those who pursue the studies 

 of Geology, Physical Geography, and the distribution of Plants, and it is 

 thus a contribution of great value to science. 



