94 



Topographical Report on the Neilgherries. 



[July 



air above, by being surrouiifled by the adjacent hills, which also is 

 highly favourable to the formation ofice,in masses or hoar-frost; where- 

 as the air at the summits of the hills, being constantly agitated by 

 strong currents, and partially warmed by the risen heat from the valleys, 

 but especially from being quite dry, whereby the moisture necessary to 

 the formation of hoar-frost must be evaporated ; offers, as far as I can 

 judge, a fair explanation of the great fall of temperature in the valleys 

 and the formation there of ice and hoar-frost, while there are hardly 

 any on the hills above. 



The medium temperature is very equable, and in a good house does 

 not vary five degrees, on an average, in the whole twenty four hours ; 

 so that delicate persons can command a temperature more even through- 

 out the year than at any other place, perhaps, in the world. The ave- 

 rage of seven years is as follows : — 



Mean temperature about 2 p. M 63* 2' 



Do. do. sunrise 49° 3' 



Do. do. for the whole month for seven 



years 56° 2i' 



In a strong wind in March, when the sky was quite clear, the ther- 

 mometer in a room without a fire stood at 64, and fell to 63 when ex- 

 posed to the sun outside, where a strong and dry easterly wind was 

 blowing. 



The soil is diluvial being chiefly lateritious, or of dark clay (very 

 productive), lying on laterite, with sufficient intervening quartoze and 

 lateritious gravel to drain it. The whole formation of the hills is pri- 

 mitive, consisting of granite overlaid with laterite, and the above men- 

 tioned clay, and feldspathic porcelain clay, all producing abundance of 

 grass, through the continued moisture of the monsoons, and the conse, 

 quent protection from the sun by the clouds, the which when withdrawn, 

 the whole face of the previously verdant hills is changed to a dusky 

 brown. The generally low degree of temperature, and the powerful 

 currents of wind, which constantly blow, would prevent or greatly di- 

 minish the bad effects of noxious exhalations, if there be any ; but, as 

 far as two years experience enables me to judge, I believe that there are 

 none, as persons have passed nights in tents in various parts of the 

 hills without having suffered the least inconvenience therefrom. 



The water is excellent, as most granitic waters are, being almost 

 chemically pure. A thermal spring is said to be in the distant Koon- 

 dahs, but I have not seen it, and my avocations will not admit of much 

 exploration. 



