GEOGRAPHICAL RELATIONS OF MEXICO. 299 



miles. The question of opening a communication 

 by a canal between the two oceans at this point, the 

 isthmus of Panama, or several others which he 

 mentions, is fully discussed by the author. He dis- 

 credits the idea that the level of the South Sea is 

 higher than that of the Gulf of Mexico, and imagines 

 that were a rupture of the intervening barrier ef- 

 fected, the current would establish itself in the di- 

 rection opposite to that usually apprehended. 



When a general view is taken of the whole sur- 

 face of Mexico, it is seen that one-half is situated 

 within the tropic, while the rest belongs to the tem- 

 perate zone. This latter portion contains 775,019 

 square miles. The physical climate of a country 

 does not altogether depend upon its distance from 

 the pole, but also upon its elevation, its proximity 

 to the ocean, and other circumstances ; so that of 

 the 645,850 square miles in the torrid zone, more 

 than threerfifths have a cold, or at least temperate 

 atmosphere. The whole interior of Mexico, in fact, 

 constitutes an immense table-land, having an eleva- 

 tion which varies from 6562 to 8202 feet above the 

 level of the sea. 



The chain of mountains which forms this vast 

 plain is continuous with the Andes of South Amer- 

 ica. In the southern hemisphere the cordillera is 

 everywhere broken up by fissures or valleys of small 

 breadth ; but in Mexico it is the ridge itself that con- 

 stitutes the platform. In Peru the most elevated sum- 

 mits form the crest of the Andes, while in the other 

 the prominences are irregularly scattered over the 

 plain, and have no relation of parallelism to the di- 

 rection of the cordillera. In Peru and New- Grenada 

 there are transverse valleys, having sometimes 4590 

 feet of perpendicular depth, which entirely prevent 

 the use of carriages ; while in New-Spain vehicles 

 are used along an extent of more than 1726 miles. 

 The general height of the table-land of Mexico is 

 equal to that of Mount Cenis, St. Gothard, or the 



