INTRODUCTION. 15 



southward by the African coast, and confined by the 

 island of Madagascar, it forms a current of consi- 

 derable force, which rounds the Cape of Good Hope, 

 and mercres into the Atlantic. Besides these, there 

 are other more local currents, which are not so easily 

 explained, such as that which constantly flows out of 

 the Baltic, and that which flows into the Mediterra- 

 nean. In each of these cases, while the main current 

 occupies the middle of the channel, there is a subor- 

 dinate current on each side close to the shore, which 

 sets in the opposite direction. As in the case of the 

 tides, it is obvious how serviceable these motions of 

 the sea often are in aiding navigation, particularly as 

 they are most strong and regular in latitudes where 

 calms often prevail. 



But we, who inhabit Western Europe, derive a much 

 more obvious advantage from this great marine river, 

 in our mild and equable climate. If we compare the 

 Atlantic coasts of North America and of Europe in 

 this respect, we shall better appreciate this advantage. 

 St. John's, in Newfoundland, is nearly on the same 

 parallel of latitude as Vannes, on the shore of the 

 Bay of Biscay; but its climate is that of Norway. 

 The coast of Labrador lies immediately opposite to 

 Ireland ; but its climate is about the same as that of 

 T.apland. On the other hand, the nearest resemblance 

 to an Ensflish climate on the American side of the 

 Atlantic, — at least so far as the mildness of the 

 winters is concerned, for the summers are far hotter, — 

 must be sought in Alabama and Florida, which cor- 

 respond in latitude to the north of Africa. 



It has been ascertained that the American climate 



