BAINS AND BIVERS. 105 



within the region of the north-east trades, and these winds carry its- 

 vapours off to the westward, and deliver them in rain to the hills, 

 and the valleys, and the rivers of Mexico and Central America. 

 The winds that bring the rains for the upper Mississippi Yalley 

 come not from the south ; they come from the direction of the 

 Eocky Mountains, the Sierra Nevada, and the great chain that 

 skirts the Pacific coast. It is, therefore, needless to search in the 

 Gulf, for the rain that comes from it upon that valley is by no- 

 means sufficient to feed one half of its springs. Let us next 

 examine the Atlantic Ocean, and include its slopes also in the- 

 investigation. 



277. The north-east trade-wind region of this ocean extends 

 S'tSlScS^^^ (§ 210) from the paraUel of 30° to the equator, 

 ply rains only for the These muds carrv their vapour before them, and. 



rivers oi Central and , . , , ,*<, , , \ • t 1 1 i r> 



South America. mcctmg the south-cast trade-wmd, the two lorm 

 clouds which give rain not only to Central America, but they drop 

 down, also, water in abundance for the Atrato, the Magdalena, the- 

 Orinoco, the Amazon, and all the great rivers of intertropical 

 America ; also for the Senegal, the Niger, and the Congo of i\.frica. 

 So completely is the rain wi'ung out of these winds for these 

 American rivers by the Andes, that they become dry and rainless 

 after passing this barrier, and as such reach the western shores of 

 the continent, producing there, as in Peru, a rainless region. 

 The place in the sea v/hence our rivers come, and whence Europe- 

 is supplied with rains, is clearly not to be found in this part of the 

 ocean. 



«^ 278. Between the parallels of 30° and 35° N. lies the calm belt 

 The calm belt of of Caucor, a rcgiou where there is no jprevaili7ig 

 litSe or nJ'rain. wiud (sco Diagram of the Winds, Plate I.). It is a 

 belt of light airs and calms — of airs so baffling that they are often 

 insufficient to carry off the "loom," or that stratum of air, which, 

 being charged with vapom-, covers calm seas as with a film, a& 

 if to prevent fe,rther evaporation. This belt of the ocean can scarcely 

 be said to fm-nish any vapour to the land, for a rainless country, 

 both in Africa, and Asia, and America, lies ^^dthin it. 



279. All Em'ope is on the north side of this calm belt. Let us 

 The North Atlantic cxtcud OUT scarch, thou, to that part of the Atlantic 

 STofJ^^ig:^;"'^ which hes between the parallels of 35° and 60° N., 

 Sone"sritb'of'au^ to sce if WO havo water smface enough there to 

 *he land. supply raius for the 8J- milhons of square miles that 



are embraced by the water-sheds under consideration. The area of 



