24 Baron N. Schilling on the Constant Currents 



the origination of these natural phenomena is at present ac- 

 counted for. 



Constant Currents and Trade-winds. Views hitherto held on 

 their origin. 



The analogy which subsists between the constant currents of 

 the different oceans, as well as between the trade-winds and the 

 equatorial currents, is most striking. 



Both in the Atlantic and in the Pacific and Indian Oceans 

 there flows from east to west, on each side of the equator, a cur- 

 rent extending over about 20 degrees of latitude* and many 

 thousand feet deep. This is named the equatorial current, 

 while for more particular designations the names of the ocean 

 and hemisphere in question are added. Between these two 

 equatorial currents, there is found in all three oceans, nearly on 

 the equator, a relatively narrow zone, in which either no current 

 or one flowing in the opposite direction is observed. The equa- 

 torial streams continue their westward course till they encounter 

 coasts, which turn aside their direction, according to the posi- 

 tion of the coasts, and give them a more or less meridional direc- 

 tion, until, in both hemispheres, in the vicinity of 40° lat. they 

 turn eastward to intersect the ocean again in this direction. 

 This latter stream, flowing from west to east, pretty well takes 

 in a zone of 10 degrees of latitude, and in all the oceans and 

 both hemispheres is met with between the 40th and 50th 

 parallels. This stream has different denominations in different 

 oceans ; but Muhry gives it the general name of the equatorial- 

 compensation stream ; for, arrived at the eastern boundary of 

 the ocean in question, the stream turns back again into the 

 equatorial region, to begin afresh its westward course. In this 

 way, in each hemisphere, regular circulations are formed, which 

 are comprehended under the denomination of rotation-currents. 

 In the centre of these circulations, about in the region of the 

 30th degree of latitude, there is in all the oceans a broad strip 

 in which no current is observed, and which is known by the 

 name of the Sargasso- sea. To these currents parallel to the 

 equator, with their included streamless zones, the trade-winds 

 with their zones of calms exactly correspond. On each side of 

 the equator there is a zone from 15 to 20 degrees broad in which 

 a constant trade-wind blows in the principal direction of east to 

 west. In the vicinity of the polar boundary of this zone the di- 

 rection of the wind is indeed mostly, in the northern hemisphere, 

 from the north-east — and in the southern, from the south-east. 

 In the middle latitudes, chiefly between the 40th and 50th 



* In the Indian Ocean the northern equatorial current, interrupted by 

 the south coast of Asia, has less breadth. 



