258 OBSERVATIONS ON THE 



The different effects produced by various degrees of rarefaction of the 

 atmosphere and its relations to moisture are such as make the thermometer 

 cease to be a correct measure of temperature, for it is not the actual, but the 

 sensible quality of it that is so important to philosophical studies. The 

 superincumbent atmosphere upon the surface of the Gangetic plains in the 

 months of November and February, when the thermometer frequently falls 

 below the freezing point without ice being formed, is an instance of cold 

 without its due effects, while in the mountains at a height of seven thousand 

 feet, as at Simla, a much higher temperature will freeze the soil a foot deep. 

 The sensibility of our feelings to those atmospheric influences is but too 

 delicate. Let one contrast the damp morning chill of the plains with the 

 frigid elasticity, and even stimulating effect of the mountain air which, 

 perhaps ten degrees higher, gives the aspect of an European winter. In. 

 one case the air being loaded with moisture, and absorption farther checked 

 by its density, a film of ice is only produced by a temperature of 28" or 30**. 

 In the other, the air is so dry and subtle that it freezes by the effect of 

 evaporation more than by mere cold. In the Intra Himalayan regions 

 this power is so much augmented by aridity that ice often disappears 

 unthawed while snow has been seen to fall when the temperature pointed 

 to 47°. In the southward hills the air must be cooled down to 37° before 

 this takes place. 



Every person in Lidia is familiar with the peculiarly mouldering 

 nature of the rainy season, though the heat is perhaps tempered tifteen or 

 twenty degrees. It is the moisture which is here the element of struc- 

 tural decay and of oppression to our feelings. In Sjnti, yaks are killed 

 in the end of September, and hung up to dry when the mid-day air is at 

 66° or 68°. It is the absence of moisture here, that produces the opposite 

 state, which is so sharply defined, that all the productions of nature, both 

 animal and vegetable, would appear to be an effect of it rather than to owe 

 their peculiar form to distant species. To this accelerated vaporization 



