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34
favour of the Dihong,
EAST ASIA.
since Wilcox and Burlton ascertained in 1825-6 that it is
evidently the main branch of the Brahmaputra. But when they
went on to
assert that the Brahmaputra itself is the lower course of the Tsangbo, the .
unexplored gap between the two rivers was no less than 300 miles long as the bird
flies, and the intervening highlands were entirely unknown. The information
brought back by Wilcox regarding the river ascended by him was also far from
sufficient to his
justify opinion on the identity of the two streams. He should
have first of all proved that the Dihong has a larger volume than the Tsangbo.
Fig.
According
14. COURSE OF THE TSANOBO.
to Markham. Scale 1 : 10,000,000.
300 Miles.
But he merely observed that at the point reached by him the Dihong was 100
yards broad, with a slow current, and, as fie supposed, an immense depth.
The is problem now confined to the narrowest limits. According to Walker's
explorations, the entirely unexplored space separating the extreme point reached by
the already mentioned Hindu pundit on the Tsangbo, and the farthest point to
which the Dihong has been ascended, is exactly 93 miles, and the difference of level
would appear to be about 7,500 feet, Were the two streams connected, the total
fall in an approximate course of 180 miles would consequently be rather over
1 in 100 yards a fall unapproached by any other river in its middle course, and
equalled only by the valleys of torrents in the heart of the mountains. Vague