Mooshye
Date September 23
Calcutta Observations 78.5 degrees
Number of Observations 9
Khasia Observations 66.3 degrees
Number of Observations 12
1 degree= 499 feet
Altitude above the Sea 4,863 feet
Pomrang
Date September 23
Calcutta Observations 82.7 degrees
Number of Observations 51
Khasia Observations 65.8 degrees
Number of Observations 51
1 degree= 369 feet
Altitude above the Sea 5,143 feet
Amwee
Date September 23
Calcutta Observations 79.9 degrees
Number of Observations 15
Khasia Observations 67.1 degrees
Number of Observations 11
1 degree= 396 feet
Altitude above the Sea 4,105 feet
Joowy
Date September 23
Calcutta Observations 79.5 degrees
Number of Observations 11
Khasia Observations 69.0 degrees
Number of Observations 7
1 degree= 567 feet
Altitude above the Sea 4,387 feet
Total Calcutta Observations 400
Total Khasia Observations 434
Mean 1 degree= 385 feet
The equivalent thus deduced is far greater than that brought out by the Sikkim observations. It indicates a considerably higher temperature of the atmosphere, and is probably attributable to the evolution of heat during extraordinary rain-fall, and to the formation of the surface, which is a very undulating table-land, and everywhere traversed by broad deep valleys, with very steep, often precipitous flanks; these get heated by the powerful sun, and from them, powerful currents ascend. The scanty covering of herbage too over a great amount of the surface, and the consequent radiation of heat from the earth, must have a sensible influence on the mean temperature of the summer months.
APPENDIX J.
ON THE MEASUREMENT OF ALTITUDES BY THE BOILING-POINT THERMOMETER.
The use of the boiling-point thermometer for the determination of elevations in mountainous countries appearing to me to be much underrated, I have collected the observations which I was enabled to take, and compared their results with barometrical ones.
I had always three boiling-point thermometers in use, and for several months five; the instruments were constructed by Newman, Dollond, Troughton, and Simms, and Jones, and though all in one sense good instruments, differed much from one another, and from the truth. Mr. Welsh has had the kindness to compare the three best instruments with the standards at the Kew Observatory at various temperatures between 180 degrees and the boiling-point; from which comparison it appears, that an error of l.5 degrees may be found at some parts of the scale of instruments most confidently vouched for by admirable makers. Dollond's thermometer, which Dr. Thomson had used throughout his extensive west Tibetan journeys, deviated but little from the truth at all ordinary temperatures. All were so far good, that the errors, which were almost entirely attributable to carelessness in the adjustments, were constant, or increased at a constant ratio throughout all parts of the scale; so that the results of the different instruments have, after correction, proved strictly comparable.