On the Influence of the Gulf Stream. 301 



after flowing nearly 3000 geographical miles. Our own islands 

 enjoy its warmth, and many a Spirula and lantJdna is cast by its 

 waters on our western shores. 



Scoresby observed its influence in Spitzbergen, in the 79° of N. 

 latitude, the Glaciers being all stopped abruptly on their descent to 

 the sea by the remnant of heat which the ocean still derives from this 

 source ; whilst Dr. Petermann has shown that the stream extends 

 beyond Spitzbergen along the coast of Siberia to an open sea near 

 the pole.^ 



Mr. Croll ~ has estimated the total quantity of water conveyed by 

 the Gulf-stream to be equal to that of a stream 50 miles broad and 

 1,000 feet in depth, flowing at the rate of four miles an hour, with 

 a mean temperature of 65°.^ Before it returns from its northern 

 journey he concludes it has cooled down at least 25°. Each cubic 

 foot of water, therefore, has carried from the tropics upwards of 1,500 

 units of heat, or 1,158,000 foot-pounds. According to the above 

 estimate of the size and velocity of the stream, 5,575,680,000,000 

 cubic feet of water are conveyed from the Gulf per hour, or 

 133,816,320,000,000 cubic feet per day. 



Capt. Maury's and Sir John Herschel's estimates are still greater 

 than Mr. Croll's, the calculation of the former giving 6,166,700,000,000 

 cubic feet per hour, and the latter 7^359,900,000,000 cubic feet per 

 hour. Sir John Herschel estimates the temperature at 86° F. 



Principal J. D. Forbes has calculated that the quantity of heat 

 thrown into the Atlantic Ocean by the Gulf-stream on a winter's 

 day would raise the temperature of the atmosphere which rests on 

 France and Great Britain from the freezing point to summer's heat.* 

 Mr. Croll has calculated the heat received by the earth from the sun 

 at the equator at the time of the equinoxes as equal to 1,780,474 

 foot-pounds per square foot of surface daily, and per square 

 mile 40,636,750,000^000 foot-pounds daily. But this represents 

 oiily 31.2 ] 870 part of the quantity of heat daily conveyed from the 

 tropics by the Gulf-stream. 



At the very time the Gulf-stream is rushing in greatest volume 

 through the Straits of Florida, and hastening to the north, there is a 

 cold stream from Baffin's Bay, Labrador, and the coasts of the north, 

 running to the south with equal velocity. This current is ever 

 flowing inshore on the North American sea-board, and beneath the 

 Gulf-stream, but does not mingle with its waters. 



It will be sufficient to remind our readers that the great cause of 

 these currents is identical with that which produces the atmospheric 

 circulation, and that it exercises an important modifying influence in 

 each case. The currents of the waters of the ocean, however, cannot 

 travel with the same freedom as those of the air, being constantly 

 aff'ected by land-barriers, which deflect or impede their course. To 



^ Lyell Principles, p. 215. 



2 Trans. Geol. Soc, Glasgow, vol. ii. p. 177. 



3 liyell gives the temperature on the authority of Prof. Bache as 80°. 

 * Travels in Norway, p. 202. 



