§G76,677. SEA ROUTES, CALM BELTS, ETC. 361 



676. The investigations that have taken place at the Observato- 

 The influence of the rv show that the influence of the land upon the 



land upon the winds t t • ^ i • i 



Kt sea. normal directions oi the wind at sea is an immense 



influence. It is frequently traced for a thousand miles or more 

 out upon the ocean. For instance, the action of the sun's rays 

 upon the great deserts and arid plains of Africa, in the summer 

 and autumnal months, is such as to be felt nearly across the At- 

 lantic Ocean between the equator and the parallel of 13° north. 

 Between this parallel and the equator, the northeast trade-winds, 

 during these seasons, are arrested in their course by the heated 

 plains of Africa, as observation shows they are in India, and instead 

 of " blowing home" to the equator, they stop and ascend over the 

 desert sands of the continent. The southeast trade-winds, arriving 

 at the equator during this period, and finding no northeast trades 

 there to contest their crossing the line, continue their course, and 

 blow home as a southwest monsoon to the deserts, where they as- 

 cend. These southwardly monsoons bring the rains which divide 

 the seasons in these parts of the African coast. The region of the 

 ocean embraced by these monsoons is cuneiform in its shape, hav- 

 ing its base resting upon Africa, and its apex stretching over till 

 within 10° or 15° of the mouth of the Amazon. Indeed, when 

 we come to study the effects of South America and Africa (as 

 developed by the Wind and Current Charts) upon the winds at 

 sea, we should be led to the conclusion — had the foot of civilized 

 man never trod the interior of these two continents — that the cli- 

 mate of one is humid ; that its valleys are, for the most part, cov- 

 ered with vegetation, which protects its surface from the sun's 

 rays ; while the plains of the other are arid and naked, and, for 

 the most part, act like furnaces in drawing the winds from the sea 

 to supply air for the ascending columns which rise from its over- 

 heated plains. Pushing these facts- and arguments still farther, 

 these beautiful and interesting researches seem already sufficient 

 almost to justify the assertion that, were it not for the great desert 

 of Sahara and other arid plains of Africa, the western shores of 

 that continent, within the trade-wind region, would be almost, if 

 not altogether, as rainless and sterile as the desert itself. 



677. Lieutenant Jansen has called my attention to a vein of 



der Nord-Amerikaansche Marine, vertaald door M. H. Jansen, Luitenant der Zee. 

 (Bijdrage.) Dordrecht, P. K. Braat. 1855. 



