57 



pics and that of the trade winds vary according 

 to the seasons, the Gulf-stream also changes it's 

 place and direction. These changes become very 

 perceptible from the 38th degree of latitude as 

 far as the great bank of Newfoundland, and are 

 observed even between the 48th degree of longi- 

 tude west of Paris, and the meridian of the 

 Azores. The variable winds of the temperate 

 zone, and the melting of the ice of the northern 

 pole, whence in the months of July and August 

 a great quantity of fresh water flows towards the 

 south, may be considered as the principal causes, 

 which modify in these high latitudes, the force 

 and direction of the Gulf-stream. 



We have just seen that between the parallels 

 of 11 and 43 degrees, the waters of the Atlantic 

 are drawn on by the currents in a continual 

 whirlpool. Supposing that a molecule of water 

 returns to the same place from which it departed, 

 we can estimate, from our present know ledge o 

 the swiftness of currents, that this circuit of 3800 

 leagues is not terminated in less than two years 

 and ten months. A boat, which may be sup- 

 posed to receive no impulsion from the winds, 

 would require thirteen months from the Canary 

 islands to reach the coast of Caraccas, ten months 

 to make the tour of the Gulf of Mexico and 

 reach Tortoise Shoals opposite the port of th e 

 Havannah, while forty or fifty days might be suf- 

 ficient to carry it from the Straits of Florida to the 



