66 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS BIETEOICOLOGY. 



Stream exercises upon the storms of the North Atlantic, which 

 take their rise within the tropics, is felt as far over even as the 

 coast of Africa: it is also felt upon those which, though not 

 intertropical in their origin, are known to visit the offings of the 

 American coasts. These gales, in whatever part of the ocean 

 east of the Gnlf Stream they take their rise, march to the north- 

 west initil they join it, Avhen they " recurvate," as the phrase is, 

 and take uj) their line of march to the north-east along with it. 

 Gales of wind have been traced from latitude 10'^ N. on the other 

 side of the Atlantic to the Gulf Stream on this, and then with it 

 back again to the other side, off the shores of Europe. By 

 examining the log-books of ships, the tracks of storms have been 

 traced out and followed for a week or ten days. Their path is 

 marked. by wreck and disaster. At a meeting of the American 

 Association for the Advancement of Science, in 1854, Mr. 

 Eedfield mentioned one which he had traced out, and in which 

 no less than seventy odd vessels had been wrecked, dismasted, 

 or damaged. 



175. More observations in and about the Gulf Stream a desideratum. — 

 Now, what should attract these storms to the Gulf Stream, is a 

 question which yet remains to be satisfactorily answered. A 

 good series of simultaneous barometric observations within and 

 on either side of the Gulf Stream is a great desideratum in the 

 meteorology of the Atlantic. At the equator, where the trade- 

 winds meet and ascend, where the air is loaded with moisture, 

 and where the vapour from the warm waters below is condensed 

 into the equatorial cloud-ring above, we have a low barometer, 



176. Certain storms make for it and follow it. — How is it with 

 the Gulf Stream when these storms from right and left burst in 

 upon it, and, turning about, course along with it? Its waters 

 are warm ; they give oif vapour rapidly ; and, were this vapour 

 visible to an observer in the moon, he no doubt would, on a 

 winter's day especially, be able to trace out by the mist in the 

 air the path of the Gulf Stream through the sea. 



177. Hoio aqueous va^your assists in producing idnds. — Let us 

 consider the effect of vapour upon winds, and then the import- 

 ance of the observations proposed (§ 175) will perhaps be better 

 appreciated. Aqueous vapour assists in at least five, perhaps 

 six, ways to put air in motion and produce winds. (1.) By 

 evaporation the air is cooled ; by cooling its specific gravity is 

 changed, and, consequently, here is one cause of movement in 



