CLIMATE. 67 



temperature, until it is suddenly succeeded by a column of 

 cold air, falling by its own weight from the tops of the snow- 

 mountains behind, depressing the temperature several de- 

 grees, and generally succeeded by a deposition of moisture 

 (according to the law which guides the capacity of air for 

 moisture), in the shape of rain or snow. In the warmer 

 latitudes, the variation is proportionably much greater, it 

 being no unusual occurrence for a current of air, approaching 

 in heat to that of a land wind, to be suddenly succeeded by 

 a blast from the opposite direction as cold as ice. This I 

 have frequently observed at Teflis, and other places bordering 

 on the Caucasus, and it is not without reason assigned as one 

 of the causes of their extreme unhealthiness at particular 

 seasons. Another consequence of the vicinity of such ranges 

 to lofty mountains is, the frequent changes of the electrical 

 state of the atmosphere, indicated by thunder-storms, heavy 

 falls of rain, &c. &c. All these effects are much modified by 

 the comparative distance and elevation of the snowy ranges, 

 but they must always operate unfavourably on the climate 

 of the lower chains, as regards equability of temperature, 

 one of the most important points connected with the choice 

 of a Sanatarium, and we are justified in considering the per- 

 fect immunity of the Neilgherries from all such disturbing 

 influences, as one of the greatest advantages of their position. 

 We shall now proceed to consider the various conditions of 

 the atmosphere, (in other words, the climate,) in detail, as 

 exhibited under the modifications of pressure, temperature, 

 and moisture ; and conclude with a succinct account of the 

 usual succession of seasons.* 



* It is necessary to observe that all the succeeding observations, 

 except when otherwise distinguished, apply to Ootacamund only. 

 K 2 



