The Winds. 251 



This, from its greater weight, preserves a relatively sluggish, 

 motion up to the equator. A c ' main equatorial current "• is 

 thus produced in the Atlantic Ocean, flowing with a velocity 

 of from two to four miles an hour towards the west (with 

 various branches towards the north and south), and finally 

 losing itself in the Carribean Sea. The level of the Gulf of 

 Mexico is thereby raised, and a stream of water, without a 

 parallel for magnitude and velocity, flows from this gulf 

 through the narrow Straits of Florida. Where it enters the 

 Atlantic Ocean, the Gulf Stream, as it is called, is thirty-two 

 miles in width, two or three hundred fathoms deep, and its 

 average velocity is about five miles an hour. Its temperature 

 is 83° Fahrenheit. 



Off Cape Hatteras the Gulf Stream leaves the American 

 coast ; and spreading itself over the Atlantic Ocean, in two or 

 three months it attains the longitude of the Azores. Beyond 

 this point, at all seasons in ordinary years, and in every direction 

 in the great ocean-space comprised between the Azores and the 

 coasts of Europe and Western Africa, the sea is of the ordi- 

 nary temperature for its latitude, and the warm water of the 

 Gulf Stream is not found. But Major Rennell has shown 

 that on two occasions — namely, in 1776, as observed by Dr. 

 Franklin, and in the winter of 182 J -2, — the warm water 

 which characterizes the Gulf Stream was found to extend 

 across this great expanse of ocean. In November and Decem- 

 ber, 1822, and January, 1822, the weather in the south of 

 England and in France was characterized as most extraordi- 

 narily hot, damp, stormy, and oppressive. The gales from W. 

 and S.W. were almost without intermission, the fall of rain 

 was excessive, and the barometer was lower than it had ever 

 been known for thirty-five years before. If an unusual velocity 

 at its outset, or a greater height than usual of the water at the 

 head of the stream, causes these invasions of the Gulf Stream, 

 these might be recognized by proper attention. As they must 

 precede by many weeks the arrival of the warm water on the 

 coasts of Europe (more than 8000 miles from its source), in 

 this manner the climatic effects arising from this stream, and 

 the occurrence of such unusual seasons upon our coasts as that 

 of 1821-2, might probably be anticipated. 



On land, where no such movement as that upon the surface 

 of the ocean can exist, the focus of greatest heat follows the 

 motion of the sun once in every year to either tropic. The 

 annually alternating winds that arise in this manner are called 

 iC monsoons/'' 



Table VI. — Mean Annual oscillation of the barometer at 

 Greenwich, above and below par height, for nineteen years 

 (1840—58). 



