§ 299. RAINS AND RIVERS. 121 



greatest 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 northeast 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 northeast 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 hemi- 

 sphere, they, in consequence of the rotation of the earth (§ 207), 

 are made to take a southeast 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 

 northwest winds of the southern hemisphere, which correspond to 

 the southwest of the northern. Continuing on to the southeast, 

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

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

 abruptly intercepted by the Andes of Patagonia, whose cold sum- 

 mit 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 sea 

 water 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 Cherraponjie, a mountain in India. 

 Colonel Sykes reports a fall there during the southwest 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 

 3"ear. Cherraponjie is not so near the coast as the Patagonia 

 range, and the monsoons lose moisture before they reach it. ^\c 

 ought to expect a corresponding rainy region to be found to 

 the north of Oregon ; but there the mountains are not so high, 

 the obstruction to the southwest winds is not so abrupt, the high- 

 lands are farther from the coast, and the air which these winds 

 carry in their circulation to that part of the coast, though it be as 

 heavily charged with moisture as at Patagonia, has a greater ex- 



