MANUAL OF THE NILAGIEI DISTRICT. 47 



of the monsoon during these months, moderate the power of its CHAP. IV, 

 rays, and reduce the radiation from the ground. The strong PART II. 

 gales which accompany the monsoons thoroughly ventilate the physical and 

 surface and remove effluvia, whilst the condensation of their Medical 

 aqueous vapour induces the frequent heavy showers, by which ^"^^^^^' ^' 

 means everything which floats in the atmosphere and is not 

 essential to its constitution is carried to the earth. The south- 

 west monsoon, being a pure sea-breeze, is remarkably healthy 

 and refreshing. The north-east monsoon, on the contrary, after 

 it has parted with its moisture, becomes cold and dry, and conse- 

 quently less wholesome. Moreover it brings with it air which has 

 lain stagnant on the plains of India during some previous months. 



The geological nature of the soil and its vegetation also exert a Effects 

 marked influence on the configuration and climate of these Hills. Ji^^^'^^lo ^^ 

 Were the granitic 1 basement rocks of the Nilagiris unprotected nature of the 

 from the denuding eff'ects of meteorological forces, they would gJ'raTa^amJ 

 doubtless have assumed the rugged physical characters and vegetation. 

 contour which are found to be identical in mountain masses of a 

 similar kind in other parts of the globe ; but, owing to the protec- 

 tion aff'orded by local peculiarities of vegetation and surface soil, 

 they rather resemble, in their rounded forms and elevated table- 

 land, with abrupt declivities, the general appearance of moun- 

 tains composed of calcareous rocks. 



The valleys between the Hills are usually damp and marshy, Valleys. 

 and in these situations, owing to an accumulation of soil washed 

 down from the hills above, particularly when forests have aided 

 in retaining and enriching the soil, very fertile spots are to be 

 found. Many forests in these situations have been felled for 

 cultivation. This may in part account for the comparative 

 absence of forest in the cultivable parts of the plateau in the 

 present day. Peat swamps, so useful for the supply of fuel, are 

 often found at the lower part of these valleys. 



Springs are to be found in almost every hill-side. Occasionally Springs, &c. 

 the water from these springs contains iron in minute quantities. 

 Many of these springs are perennial, whilst others cease to flow 

 towards the end of the dry season. Being fed by the rain which 

 has percolated through the primitive rocks, of which the hills are 

 composed, they are, as is usual with waters derived from a similar 

 source, of the most wholesome quality. At Ootacamand a great 

 number of small rivulets, derived from springs on the Doddabetta 

 range, converge, forming a stream which passes through the 

 lowest part of the valley. 



See chapter on Geology. There is no granite on the Hills. The rocks referred 



to are gneissose. — Ed 



