RAINS AND RIVERS. 127 



of rain. They should be on the slopes -of those mountains 

 which the trade-winds or monsoons first strike after hav- 

 ing "blown across an extensive tract of ocean. The more 

 abrupt the elevation, and the shorter the distance between the 

 mountain top and the ocean (§ 298), the greater the amount of 

 precipitation. If, therefore, we 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, we ought to find such a place of heavy 

 rains. Commencing at this parallel of 30°, therefore, in the 

 North 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 course in the upper 

 stratum of winds through the southern hemisphere, they, in 

 consequence of the rotation of the earth (§ 207), are made to 

 take a south-east course. They keep in this upper stratum 

 until they reach the calms of Capricorn, between the parallels of 

 30° and 40°, after which they become the prevailing north-west 

 winds of the southern hemisphere, which correspond to the 

 south-west of the northern. Continuing on to the south-east, 

 they are now the surface winds ; they are going from warmer to 

 cooler latitudes; they become as the wet sponge (§ 292), and are 

 abruptl}^ intercepted by the Andes of Patagonia, whose cold 

 summit compresses them, and with its low dew-point squeezes 

 the water out of them. Captain King found the astonishing fall 

 of water here of nearly thirteen feet (one hundred and fifty-one 

 inches) in forty-one days; and Mr. Darwin reports that the 

 surface water of the sea along this part of the South American 

 coast is sometimes quite fresh, from the vast quantity of rain 

 that falls. A similar rain-fall occurs on the sides of Cherra- 

 ponjie, a mountain in India. Colonel Sykes reports a fall there 

 during the south-west monsoons of 605i inches. This is at the 

 rate of 86 feet during the year ; but King's Patagonia rain-fall is 

 at the rate of 114 feet during the same period. Cherraponjie is 

 not so near the coast as the Patagonia range, and the monsoons 

 lose moisture before they reach it. We ought to expect a corre- 

 sponding rainy region to be found to the north of Oregon ; but 

 there the mountains are not so high, the obstruction to the 

 south-west winds is not so abrupt, the highlands are farther 

 from the coast, and the air which these winds carry in their 



