CHAP. viii.J THE GULF-STREAM. 381 



with it of the waters of the river Amazon, it rises to 

 one hundred miles (6 '5 feet in a second), but it soon 

 falls off again when it gets into the Caribbean sea. 

 Plowing slowly through the w r hole length of this sea, 

 it reaches the Gulf of Mexico through the Strait of 

 Yucatan, when a part of it sweeps immediately round 

 Cuba ; but the main stream "having made the circuit 

 of the Gulf of Mexico, passes through the Strait of 

 [Florida ; thence it issues as the ' Gulf-stream ' in a 

 majestic current upwards of thirty miles broad, two 

 thousand two hundred feet deep, with an average 

 velocity of four miles an hour, and a temperature of 

 86 Fahr. (30 C)." l The hot water pours from the 

 strait with a decided though slight north-easterly 

 impulse on account of its great initial velocity. Mr. 

 Croll calculates the Gulf-stream as equal to a stream 

 of water fifty miles broad and a thousand feet deep 

 flowing at a rate of four miles an hour ; consequently 

 conveying 5,575,680,000,000 cubic feet of water per 

 hour, or 133,816,320,000,000 cubic feet per day. This 

 mass of water has a mean temperature of 18 C. as it 

 passes out of the gulf, and on its northern journey it 

 is cooled down to 4*5, thus losing heat to the amount 

 of 13* 5 C, The total quantity of heat therefore trans- 

 ferred from the equatorial regions per day amounts 

 to something like 154,959,300,000,000,000,000 foot- 

 pounds. 2 



This is nearly equal to the whole of the heat 



1 Physical Geography. From the 'Encyclopaedia Britannica.' By 

 Sir John F. W. Herschel, Bart., K.H.P. Edinburgh, 1861, p. 49. 



2 On Ocean Currents. By James Croll, of the Geological Survey of 

 Scotland. Part I. Ocean Currents in relation to the Distribution of 

 Heat over the Globe (Philosophical Magazine. February 1870.) 



