A GENERAL SKETCH OF SUMATRA* 346 
three, and sometimes more, principal ranges are found with 
wide table lands, plains or vallies between them, watered 
by numerous streams, and in some places containing lakes, as 
in the principal Korinchi plain, the great Malayan plain 
of Menangkabau and the Bata' plain of Tobali. The most 
western ranges form the water shed, and as the land to the 
west of it, chiefly hills, is not more than 25 miles broad, 
about one-fifth only of the waters of the island fall into the 
Indian Ocean,—the Straits of Malacca and the Java sea 
receiving the remainder, in nearly equal proportions as 
regards the drainage of the mountains, but with a large ex¬ 
cess to the latter from the wide plain traversed by the rivers 
that disembogue into it. 
The western margin of the belt, washed by the strong 
waves of the Indian Ocean, has retrograded to the eastward, 
the sediment of the rivers and the debris of the coast being 
carried away instead of being deposited. The northern 
part of the east coast, exposed to the assault of the Bay of 
Bengal, has retained its ancient dimensions, if it has not 
contracted, but as soon as the open sea is exchanged for 
the Straits of Malacca, the mountain belt begins to retire 
from the coast, and a great alluvial plain commences, 
which, to the south of the S. E. extremity of the Batta’ 
country opposite Parcelar hill, where the Peninsular and 
Sumatran belts approach nearest each other, expands fo a 
breadth varying from 60 to 110 miles. The length is about 
600 miles and the average breadth about 70 miles which 
gives a surface of about 42,000 square miles.* 5 If to this 
we add 1,500 square miles for the area of the fiat alluvial 
land to the north of the great plain, we shall have 128,500 
miles as the area of the whole island, + the mountain region 
occupying about two thirds. The islands on the west coast 
give a further surface of 5,000 miles to be added to the 
elevated region, and this will make it almost exactly double 
the size of the alluvium. 
RANGE AND NUMBERS OF THE DIFFERENT RACES OF INHABITANTS. 
I. Vlild Tribes . 
There are two races which, not being confined to par- 
* We bare already described this plain and the mode of its formation, 
Sketch of the Physical Geography and Geology of the Malay Peninsula , 
Journ. Ind, Arch. vol. n p. 129—132 
•f This result is nearly identical with the cross estimate of Lieut. Mevitle 
van Carnbee, which is 8,035 leagues=128,5G0 Epg. sq. geo. miles, lb, p. 176, 
