Physical Geography of Hindo start. 345 



run northward and southward in the direction of the meri- 

 dian right across the path of the Trade-Winds. A similar 

 ridge, though of less magnificent dimensions, traverses the 

 peninsula of Hindostan, increasing in altitude as it ap- 

 proaches the line, — attaining an elevation of 8500 feet at 

 Dodabetta, and above 6000 in Ceylon. The Alps in Europe 

 and the gigantic chain of the Himalayas in Asia, both far 

 south in the temperate zone, stretch from east to west, and 

 intercept the aerial current from the north. Others of lesser 

 note, in the equatorial or meridional, or some intermediate 

 direction, cross the paths of the atmospherical currents in 

 every direction, imparting to them fresh supplies of cold, as 

 they themselves obtain from them warmth in exchange ; in 

 strictness, the two operations are the same. Magnificent 

 and stupendous as are the effects and results of the water 

 and of air acting independently on each other, in equalising 

 the temperature of the globe, they are still more so when 

 combined. One cubic inch of water when imbued with a 

 sufficiency of heat, will form one cubic foot of steam — the 

 water before its evaporation, and the vapour which it forms, 

 being exactly of the same temperature, though in reality, in 

 the process of conversion, 1700 degrees of caloric have been 

 absorbed or carried away from the vicinage, and rendered 

 latent or imperceptible ; this heat is returned in a sensible 

 and perceptible form, the moment the vapour is converted 

 once more into water. The general fact is the same in the 

 case of vapour carried off by dry air at any temperature that 

 may be imagined (for down far below the freezing point 

 evaporation proceeds uninterruptedly), or raised into steam 

 by artificial means. The air, heated and dried as it sweeps 

 over the arid surface of the soil, drinks up by day myriads of 

 tons of moisture from the sea — as much indeed as would, 

 were no moisture restored to it, depress its whole expanse at 

 the rate of four feet annually over the surface of the globe. 

 The quantity of heat thus converted from a sensible or per- 

 ceptible to an insensible or latent state, is almost incredible. 

 The action equally goes on, and with the like results, over 

 the surface of the earth, where there is moisture to be with- 

 drawn, as over that of the sea. But night, and the seasons of 

 the year, come round, and the surplus temperature thus 



