CHAPTER V. 



CLIMATE. 



On this very important subject, I may be excused for en- 

 tering at some length, and as what I shall have to state is 

 the result principally of my own observations, closely direct- 

 ed to its nature and effects, during the whole of a residence 

 of nearly three years, I have no hesitation in claiming for my 

 statements the merit of accuracy at least. 



There are three circumstances connected with the Neil- 

 gherries which must have a material effect on their climate. 



The first is, their elevation above the level of the sea, and 

 their being placed between two seas. 



The second, their position near the line of demarcation of 

 the two monsoons. 



The third, their isolated position, at a great distance from 

 mountains or table-land, of equal or nearly equal height. 



I. The temperature of the air, as has been ascertained by 

 a number of experiments, and elaborate calculations founded 

 thereon, undergoes a regular and graduated diminution, as it 

 becomes more rarefied in ascending from the surface of the 

 earth, owing, as is well known, to its increased capacity for 

 caloric. A variety of formulse have been given for calculat- 

 ing the exact reduction of temperature at given heights, but 

 it will be sufiiciently accurate for our purpose to say, that at 



