BOTANICAL INFORMATION. 29 
of the snowy Himalaya as I did in Sikkim, and all we can see from 
these (the Khossya) mountains, appears to confirm it. Dr. Thomson 
has visited the Karakoraur Pass, and finds it to be as laid down in 
your map to ‘ Asie Centrale.” He regards the Karakoraur and Muztagh 
as the real continuation of the axis, which runs north-west from Man- 
sarowar. The latter is, indeed, another nœud, from which three chains 
of mountains radiate, one dividing the Indus from the Sutlej, another 
north of the former river, and another south of the latter. In fact, 
the course of the Indus and Sutlej much resembles that of the 
Soubansiri and Yarou, the latter being the Dihong, and finally the 
Burrampooter. With regard to atmospheric phenomena, I found the 
south-east wind to prevail up to 18,000 feet; whereas at 24,000 the 
westerly current is perennial. The south-east is all but perennial in 
Sikkim, but is considerably checked by the Himalaya; still it keeps 
"Thibet cloudy and showery from May till October. 
The south-east monsoon hardly reaches Sikkim, the currents being 
generally between south and south-west. These, passing between the 
Garrows and Rajmahal mountains, cause the Sikkim-Himalaya to be — 
much wetter than the Bhotan mountains, which are sheltered by the 
Khossya. In the latter, the rain-fall is excessive, 350 inches last year 
at Churra, and 120 this last Jury. I have several times carefully 
measured 11 inches in 12 hours! There is no error in my instru- 
ments or those established at Churra. The atmospheric pressure, 
temperature, and wet-bulb, I register as often as is possible, without 
interfering with my other pursuits ; and I find that a thermometer buried 
at three feet, gives very valuable results. 
The atmospheric tide is uniform as to time at all elevations, but the 
amount gradually diminishes, and progressively with the elevation,— 
at 17,000 feet it appears to be but a few thousandths of an inch. I 
almost invariably read off all the instruments seven times in the twenty- ce 
four hours, and I have horary observations from all heights, up to 16,000 — 
feet ; I take the same times as at the Calcutta Observatory. ae 
For geodetical observations I have but little leisure, and confine 
myself toa careful survey of my route, and occasionally the elevations 
of remarkable distant mountains. The survey, and numberless baro- 
metric observations over all parts of Sikkim, may afford elements for 
a computation of the mean mass of that section of the Himalaya. - 
Vegetation I have found up to 18,500 feet in Thibet, Herbaceous 
plants are sufficiently abundant at 18,000, in certain spots; aud c uw. 
