HIMALAYAS ON THE PLUMB-LINE IN INDIA. 
75 
Ladak, 9995 ; but this last is “'in a hollow, the surrounding plateau rising to 13,430 
feet.” Iskardo is 6300 feet; but “south of Iskardo the plateau Deotsuh rises to 
1 1,977 feet.” “There are, properly speaking,” Humboldt observes, “ very few plains 
[in this part of the Enclosed Space now under consideration] ; the most considerable 
are those between Gertope, Daba, Schang-thung, the native country of the shawl 
goat, and Shipke (10,450 feet), — those around Ladak, which have an elevation of 
13,430 English feet, and [as noticed above] must not be confounded with the de- 
pression in which the town is situated, — and lastly, the plateau of the sacred lakes 
of Manasa and Ravanahrada (probably 15,000 feet) From many carefully col- 
lected measurements of elevation I think I may say,” he adds, “ that the plateau of 
Thibet, between 73° and 85° east longitude, does not reach a mean height of 1800 
toises, or 11,510 English feet.” In addition to these observations, I may add, that 
the Survey Map of India, No. 65, shows that the bed of the Sutledge at the point 
marked S in fig. 4 is 10,792 feet. 
As the result of these data, I shall take the elevation of the dotted line QR, marked 
in fig. 4, and passing through Leh and H’Lassa, to be 10,000 feet, the greater portion 
being 11,000 or more, and the extremities somewhat less. This will be rather under 
the mark than above it. 
37 . With regard to the parts of the Enclosed Space further removed, Humboldt 
observes, — “The mean height of this part of Gobi [between the sources of the river 
Selenga, lat. 50°, long. 102°, and the great wall of China, 600 geographical miles] is 
barely 4,264 English feet Enghi is half-way, and is only about 2558 feet.” I shall 
therefore take the point M, which represents the situation of Enghi, to be 2560 feet. 
I gather from the general account of the country between the great plateau of Thibet 
and the parts about Enghi and beyond that place, that, although it varies in its sur- 
face, it has a general slope down to Enghi, and then a rise again to the mountains. 
In describing the parts to the north of NP, the Kuen-Luen range, Humboldt states, 
that between that and the Thian-Schan ranges there is a considerable depression. 
“ Carl Zimmerman,” he remarks, “ has made it appear extremely probable, that the 
Tarim depression, that is, the desert between the mountain chains of Thian-Schan 
and Kuen-Luen, where the steppe-river Tarim-gol empties itself into the Lake of Lop, 
which used to be described as an Alpine lake, is hardly 1279 English feet above the 
level of the sea.” Again, he informs us that the line KL (in fig. 4), though once 
supposed to be a chain of mountains, is a line of broken country ; and the west of 
this line we know to be lowland. 
38. Guided, then, by such data as I have been able to gather, I assume, as the best 
general representation of the facts, that the Doubtful Region of the Enclosed Space to 
the north of QR, and outside the circle about A which bounds the Known Region, 
slopes gradually from 10,000 feet down to 2560 at M, and then rises again at the 
same angle to J. And I shall assume that the parts of the same region to the south 
of QR, and not ineluded in the Known Region, slopes at four times that rate. In 
