248 DR. HOOKER'S MISSION TO INDIA. 
saturation — 0:737. The dryness of the air, in the damper-looking 
and luxuriant river-bed, is owing to the heated rocks of its channel ; 
while the humidity of the atmosphere over the drier-looking hill where 
we encamped, is due to the moist easterly wind then blowing. 
Our course lay over a still more rugged country than yesterday, 
though altogether similar in other respects. Giddy and foot-sore with 
leaping from rock to stone, we attempted the jungle, which proved 
utterly impervious. Some masses of gneiss, washed down the river, 
were curious, from being full of compressed nodules of quartz, of 
excessive hardness, and a foot or so long. 
On turning a bend of the river, the mountains of Bhotan suddenly 
presented themselves, abruptly crossing the river's course, with the 
Teesta flowing at their base; clambering round a precipice of 
slate-rocks, we emerged at the angle formed by their junction. It 
was simply the meeting of three defiles,—that of the Rungeet, which 
we had followed from the west, of the Teesta, coming from the north, 
and of their united streams, flowing south. The natural features of all 
were the same—rugged watercourses, rushing in very deep channels, 
bounded by mountains, forest-clad at the base, and so lofty and steep 
that their tops were shut out from view. 
We were not long before enjoying the water, when I was surprised 
to find that of the Teesta singularly cold, and the thermometer proved 
it to be full seven degrees colder than the Rungeet. At the salient 
angle (a rocky peninsula) of their junction, you may almost place one 
foot in the cold stream, and the other in the warmer. This is, no 
doubt, due to the Teesta flowing south, and thus having less of the 
sun, and partly to its draining snowy hills, during a much longer 
part of its course. The temperature of one was 67:57, of the 
. other 60°5°. 
There is a no less notable difference in the colour of the two rivers, 
the Teesta being sea-green and muddy, the Great Rungeet dark-green 
and very clear. They meet at an angle, and the waters preserve their 
colour for some hundred yards, the line separating the two being most 
distinctly drawn. The Teesta, ay main stream, is much the broadest 
(about eighty or a hundred yards wide at this season), the most rapid, 
. and deepest. The rocks which skirt its bank are covered with a mud 
.. deposit, which I nowhere observed along the Great Rungeet, and which 
= shows a remarkable difference between the two rivers, and is owing 
