OCEAN CURRENTS 233 



while two polar currents also exist, each flowing westward and 

 forming a complete circulation with the eastward-flowing northern 

 arm of the main circulation. The configurations of the lands are 

 largely responsible for the course of the currents in the different 

 oceans. Broadly outlined, the currents of the several oceans and 

 its main dependencies are as follows : 



The Atlantic Ocean. The North Equatorial current is somewhat 

 variable in its position, its southern border ranging from 6° north 

 latitude in March to 12° north latitude in September, and with an 

 average velocity of 15 to 17 nautical miles per day, or from 32 to 

 36.5 cm. per second, 1.15 to 1.3 km. per hour,* the maximum 

 rising to 2.4 km. per hour or over. The direction of this current 

 is west-southwest to west, east of longitude 35°, then turns due 

 west and becomes west-northwest at the Lesser Antilles. 



The South or principal Equatorial current is of a very constant 

 character, and crosses the equator diagonally. Its southward ex- 

 tent is near 15° south latitude, while its northern border is already 

 i" north latitude in the meridian of Greenwich during the winter 

 and spring months. Its average velocity in June, July and August is 

 20 to 24 nautical miles in 24 hours, or from 1.58 to 1.85 km. or 

 more per hour, while velocities as high as y2 nautical miles per 24 

 hours (5.55 kilometers per hour) occur. The current divides at 

 Cape St. Roque, the eastern point of South America, one arm 

 passing southward to become the Brazil current and the other 

 uniting with the North Equatorial current to produce the Guiana 

 current, which later becomes the Gulf Stream. The velocity of 

 this northern arm near Cape St. Roque is not infrequently from 

 30 to 60 nautical miles per 24 hours (2.3 to 4.6 kilometers per 

 hour). The Guiana stream is continued as the Caribbean stream, 

 with a velocity of 24 to ^2 nautical miles per day (1.85 to 5.55 

 km. per hour). It here becomes a veritable sea in motion rather 

 than a single stream. In the Gulf of Mexico it bends eastward and 

 leaves between Florida and Cuba as the warm Gulf Stream, flowing 

 at first eastward, then turning northward between Florida and the 

 Bahama banks, and then crosses the North Atlantic as the Gulf 

 Stream or West-wind drift. At the Florida Straits the average 

 annual velocity is y2 nautical miles per day (5.55 km. per hour), 



* The nautical or geographic mile (Seemeile) as defined by the United States 

 Coast Survey is "equal to one-sixtieth part of the length of a degree on the 

 great circle of a sphere whose surface is equal to the surface of the earth." This 

 makes the value of a nautical mile 6,080.27 ft. or 1,853.248 meters. The Brit- 

 ish admiralty knot is 6,080 ft. The German Seemeile, in terms of which the 

 following measurements are given, is equal to i. 852016 km. or 6079.55 ft. 



