OCEAN CURRENTS 239 



West-wind drift is again continued in part in the northward-flowing 

 West Australian current, the close analogue of the Benguelan cur- 

 rent of the South Atlantic. The velocity of this current generally 

 ranges from 18 to 36 nautical miles per day, though sometimes it is 

 scarcely perceptible. The main part of the West- wind drift, how- 

 ever, continues eastward past Cape Leeuwin and along the South 

 Australian coast past Tasmania to the Pacific, forming part of the 

 great circumpolar current of the Antarctic region. That this great 

 eastward drift around the antarctic continent is a reality has been 

 shown by many tests with floating bottles, one of which, thrown 

 overboard December 16, 1900, off the Patagonian coast (long. 60° 

 W.), was picked up June 9, 1904, on the north coast of New 

 Zealand (long. 172°) having traveled in 1,271 days a distance of 

 10,700 nautical miles, or nearly 2/3 the circumference of the earth, 

 between latitude 40° and 50° south, a distance equal to that from 

 pole to pole, or an average of 8^2 nautical miles per day. (Map, 

 Krummel-42 : 6//.) 



A characteristic accompanying feature of the wind-drift cur- 

 rents is a vertical compensatory movement, the upwelling of the 

 colder, deeper waters where the velocity of the surface stream is 

 such that the lateral compensation is insufficient. An example of 

 this has already been cited in the tongue of deep-green, colder wa- 

 ter extending westward from the Galapagos into the blue warm 

 water of the South Equatorial current of the Pacific. A similar 

 phenomenon occurs along the west American coast, where the Cali- 

 fornia current draws up the colder, deeper water on its landward 

 side. This is likewise the case in the Canary and Benguelan 

 streams, as well as along the west coast of South America. The 

 upwelling follows the wind, while a compensating downward move- 

 ment of the warmer water must occur before the wind. This ex- 

 plains the phenomenon that a persistent land breeze will cause the 

 upwelling along the coast of the colder waters, the warmer being 

 blown out to sea, while a sea breeze brings the warmer surface wa- 

 ters. Thus it is observed at the bathing beaches on the North Ger- 

 man coast that the north winds cause a warming, but south winds 

 a distinct cooling of the water. 



Currents in Mediterraneans and Epicontinental Seas. 

 The currents of intracontinental water bodies are generally mere 

 branches of the main oceanic circulation, and sometimes indeed, as 

 in the case of the Caribbean and Mexican seas, are an integral part 

 of it. The circulation of the North Sea is a southward-l)ending 

 branch from the Gulf Stream, and the main currents of the East 

 Greenland mediterranean are also a part of this larger circulation. 



