126 niTSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



are felt by the air which the south-cast trade-winds bring to the 

 equatorial Doldrums of the Indian Ocean : it rushes over into 

 the northern hemisphere to supply the upward draught from the 

 heated plains as the south-west monsoons. The forces of diumal 

 rotation assist (§113) to give these winds their westing. Thus 

 the south-east trades, in certain parts of the Indian Ocean, are 

 converted, during the summer and early autumn, into south- 

 west monsoons. These, then, come from the Indian Ocean and 

 Sea of Arabia loaded with moisture, and, striking with it per- 

 pendicularly upon the Ghauts, precipitate upon that narrow 

 strip of land between this range and the Arabian Sea an amount 

 of water that is truly astonishing. Here, then, are not only the 

 conditions for causing more rain, now on the west, now on the 

 east side of this mountain range, but the conditions also for the 

 most copious precipitation. Accordingly, when we come to 

 consult rain gauges, and to ask meteorological observers in 

 India about the fall of rain, they tell us that on the western 

 slopes of the Ghauts it sometimes reaches the enormous depth of 

 twelve or fifteen inches in one day.* Were the Andes stretched 

 along the eastern instead of the western coast of America, we 

 should have an amount of precipitation on their eastern slopes 

 that would be truly astonishing ; for the water which the Ama- 

 zon and the other majestic streams of South America return to 

 the ocean would still be precipitated between the sea-shore and 

 the crest of these mountains. These winds of India then con- 

 tinue their course to the Himalaya range as high winds. In 

 crossing this range, they are subjected to a lower temperature 

 than that to which they were exposed in crossing the Ghauts. 

 Here they drop more of their moisture in the shape of snow and 

 rain, and then pass over into the thirsty lands beyond with 

 scarcely enough vapour in them to make even a cloud. Thence 

 they ascend into the upper air, there to become counter-currents 

 in the general system of atmospherical circulation. By studying 

 Plate YIII., where the rainless regions and inland basins, as 

 well as the course of the prevailing winds, are shown, these 

 facts will become obvious. 



299. The regions of greatest p-ecipitation — Cherraponjie and 



Patagonia. — We shall now be enabled to determine, if the 



views which I have been endeavouring to present be correct, 



what parts of the earth are subject to the greatest fall 



* Keith Johnston. 



