478 CURRENTS AND WHALING. 



as we neared the coast, by the equatorial stream that sets down the 

 Mozambique Channel. This slream is usually confined to narrow 

 limits, but at some seasons becomes strong enough to throw its waters 

 in a southwest direction beyond the Aguillas Bank. There is little 

 doubt that this equatorial stream is superficial, overlying the Southern 

 Polar Stream, a portion of which latter, touching the Aguillas Bank, 

 is forced up by that obstruction to the surface. This is evident by its 

 reducing the temperature of the waters on soundings at the Cape 

 to 62°. This Polar Stream is divided by the Cape: the eastern part 

 sets along the east coast of Africa as a submarine stream, and on 

 reaching the island of Madagascar is found to flow north, along its 

 west shores. The other and larger portion is deflected, and flows to 

 the northward, along the west coast, and finally forms the Great Equa- 

 torial Stream of the South Atlantic. 



We have seen that a great equatorial stream, flowing westward, is 

 found both in the Atlantic and Pacific. One also, according to Hors- 

 burgh, exists in the Indian Ocean, in the latitude of 3° N., which may 

 be traced to that polar stream which we have seen to flow along the 

 western coast of New Holland, and which must of necessity sweep the 

 coast of Java and Sumatra. This stream has in the Indian Ocean 

 been observed to flow at the rate of fifty-six miles in twenty-four hours. 

 Upon the same authority, it appears that on the Malabar coast a 

 current sets constantly to the southward. 



About the Chagos Archipelago, the currents are periodic, setting 

 west and northwest during the prevalence of the southeast monsoon, 

 and southeast in the months of December and January, when the wind 

 blows from the northwest. About the Comorro Islands, on the con- 

 trary, the prevailing current is from the westward; and off the north 

 end of Madagascar, likewise, a westerly current prevails throughout 

 the year. On this account the ports of that island are difficult to make, 

 and ought to be approached from the windward, as it would be difficult 

 to beat up to them against the current. 



In the Mozambique Channel, a current sets northward, along the 

 western shore of Madagascar ; while on the coast of Africa opposite, 

 the water sets almost continually to the south. But on the same coast 

 to the north of the line, a weak current is found setting towards the 

 Persian Gulf, and thus causing the current we have stated to run 

 southwards on the Malabar coast. 



The Equatorial Stream of the South Atlantic may be cited as fur- 

 nishing a good instance of the effect that currents may produce on 

 climate. It always includes the island of Anno Bon within its influ- 

 ence, while St. Thomas, in longitude 6^° E., and immediately under 



