384 THE CLIMATE OF IRELAND, AND 



an hour. Following the line of the coast from the Straits, it 

 trends in a north-easterly direction as far as the great hank of 

 Nantucket, off Newfoundland, where its direction is changed to 

 easterly ; and it leaves the land near Cape Fear, and crosses the 

 Atlantic. Here reaching the colder water, it rises to the surface 

 "by its relative lightness, while, at the same time, it spreads super- 

 ficially. When it reaches the meridian of 38 W. longitude, it 

 subdivides, the main portion of the current proceeding in a north- 

 Avesterly direction to the North Sea, hathing the western coasts of 

 Ireland and Scotland on its way while another portion bends 

 round to the southward, and forms a great eddy not far from the 

 Azores, in the midst of which is found that vast floating mass of 

 .sea-weed known as the sargasso, which lies between the Azores 

 and the Cape de Verd Islands. It thus at length rejoins the 

 waters of the Equatorial sea, and completes the circuit of the 

 Atlantic. 



Confining our attention, for the present, to that portion of the 

 circuit which is more especially designated as the Grulf-Stream, 

 and whose limits are the Straits of Florida and the Azores, we 

 find that it runs its entire course of 3000 miles in 78 days ; so 

 that its average rate of progress is 38 miles per diem. Its speed is, 

 however, very different in different parts of its course. In the 

 Straits of Florida it has a velocity of 100, and sometimes 120 

 miles in the day ; but by the expansion of its waters this is soon 

 lessened. Its average velocity in the first portion of its course 

 /. e., from its origin to the point at which it leaves the American 

 shore is 63 miles a day ; in mid- Atlantic it is 55 miles ; and in 

 longitude 42|, where it begins to bend southward, it is 35 miles. 



And the temperature of the waters decreases with their speed, 

 although much less rapidly. When they issue from the Gulf of 

 Mexico, they have a temperature of 86 Fahr. ; and near the 

 termination of their course at the Azores, in 40 W. longitude, 

 they have a temperature of 74, having lost only 12 in traversing 

 a space of 3000 miles. It is to this great mass of heated water, 

 and to the westerly and south-westerly winds which carry to us 

 the heated air above it, that we owe the genial climate of the 

 British islands. 



A circuit of waters, similar in its principal features, is per- 

 formed in the South Atlantic also. I have already mentioned 

 that the great Equatorial current breaks into two at the Cape 



