BAINS AND RR^RS. 121 



moiis deptli of twelve or fifteen inches in one day.* "Were the 

 Ancles 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 Amazon and the other majestic streams of South 

 America retm^n to the ocean would still be precipitated between 

 the sea-shore and the crest of these mountains. These winds of 

 India then continue theu' course to the Himalaya range as dry 

 winds. In crossing this range, they are subjected to a lower tem- 

 peratm-e than that to which they were exposed in crossing the 

 Ohauts. 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 coimter- 

 ourrents in the i2,-eneral system of atmospherical circulation. By 

 fitud}dng Plate YIII., where the rainless regions and inland basins, 

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

 will become ob^dous. 



299. The Fiegions of Greatest Freciiyitation. — We shall now be 

 The regions of great- enabled to deteiTuiue, if the views which I have 

 €he?raS£^^J~ ^^^^ cndeavouriug to present be correct, w^hat parts 

 Patagonia. ' q£ ^j^g g^rth are subject to the greatest fall of rain. 

 They should be on the slopes of those mountains which the trade- 

 winds or monsoons first strike after having blown across an ex- 

 tensive tract of ocean. The more abrupt the elevation, and the 

 shorter the distance between the mountain top and the ocean 

 {§ 298), the greater the amoimt of precipitation. If, therefore, w^e 

 commence at the parallel of about 30^ north in the Pacific, where 

 the north-east trade-winds first strike that ocean, and trace them 

 through their circuits till they first meet high land, w^e ought to 

 find such a place of heavy rains. Commencing at this parallel 

 of 30^, therefore, in the Xorth Pacific, and tracing thence the 

 course of the north-east trade-winds, we shall find that they blow 

 thence, and reach the region of equatorial calms near the Caroline 

 Islands. Here they rise up ; but, instead of pursuing the same 

 com'se in the upper stratum of winds through the southern hemi- 

 sphere, they, in. consequence of the rotation of the eai-th (§ 207), 

 are made to take a south-east course. They keep in this upper 

 stratmn until they reach the calms of Capricorn, between the 

 parallels of 30"" and 40^, after which they become the prevailing 



* Keith Johnston. 



