410 COSMOS. 



the volcano of Jorullo. We are indebted for these remark- 

 able geognostic accounts from the Mantschurei to the indus- 

 try of W. P. Wassiljew (Geog. Bote, 1855, heft v., s. 31), and 

 to an essay by M. Semenow (the learned translator of Carl 

 Hitter's great work on Geology), in the 17th volume of the 

 Proceedings of the Imperial llussian Geographical Society. 



In the course of the investigations into the geographical 

 distribution of volcanoes, and their frequent occurrence on 

 islands and sea-coasts ; that is to say, on the margins of con- 

 tinental elevations, the probable great inequality in the depth 

 to which the crust of the earth has hitherto been penetrated 

 has also been frequently brought under consideration. One 

 is disposed to believe that the surface of the internal molten 

 mass of the earth's body lies nearest to those points at which 

 the volcanoes have burst forth. But, as it may be conceived 

 that there are many intermediate degrees of consistency in 

 the solidifying mass, it is difficult to form a clear idea of any 

 such surface of the molten matter, if a change in the com- 

 prehensive capacity of the external firm and already solidified 

 shell be supposed to be the chief cause of all the subversions, 

 fissures, upheavals, and basin-like depressions. If we might 

 be allowed to determine what is called the thickness of tho 

 earth's crust in an arithmetical ratio deduced from experi- 

 ments drawn from Artesian wells and from the fusion-point 

 of granite that is to say, by taking equal geothermal de- 

 grees of depth* we should find it to be 20^ geographical 

 miles, or y^g-th of the polar diameter.! But the influences 



as was shown so early as the 7th century of our era, by minute descrip- 

 tions given under the Dynasty of Sai (Klaproth, Tableaux Historiqucs 

 de FAsie, p. 204), an independent chain running east and west, parallel 

 to the Himalaya, at a distance of about 7 degrees of latitude. The 

 brothers Hermann and Robert Schlagintweit are the first who have had 

 the courage and the good fortune to traverse the chain of the Kuen-lu'n, 

 setting out from Ladak, and reaching the territory of Khotan, in the 

 months of July and September, 1856. According to their observations, 

 which are always extremely careful, the highest water-shedding mount- 

 ain chain is that on which is situated the Karakorum pass (18,304 feet), 

 which, stretching from southeast to northwest, lies parallel to the oppo- 

 site southerly portion of the Himalaya (to tlie west of Dhawalagiri). 

 The rivers Yarkland and Karakasch, which form a part of the great 

 water system of the Tarim and Lake Lop, rise on the northeastern slope 

 of the Karakorum chain. From this region of water-springs the trav- 

 elers arrived, by way of Kissilkorum and the hot springs (120 F.), at 

 the small mountain lake of Kiuk-kiul, on the chain of the Kuen-liin, 

 which stretches east and west (Report No. viii., A<jra r 1857, p. G). 



* Cosmos, vol. i., p. 46, 174; see above, p. 37-40. 



f Arago (Astron. Populain 1 , t. iii., p. 248) adopts nearly the same 



