DIVERSITY OF CLIMATE. 301 



On the declivities of the cordil'lera, at the eleva- 

 tion of 3937 or 4921 feet, there prevails a mild cli- 

 mate, never varying more than four or five degrees. 

 To this region, of which the mean annual tempera- 

 ture is from 68 to 69*8, the natives give the name 

 otTierras templadas. Unfortunately these tracts are 

 frequently covered with thick fogs, as they occupy 

 the height to which the clouds usually ascend above 

 the level of the sea. 



The plains which are elevated more than 7218 feet 

 above that level, and of which the mean temperature 

 is under 62*6, are named Tierras frias. The whole 

 table-land of Mexico belongs to this description, 

 which the natives consider cold, although the ordi- 

 nary warmth is equal to that of Rome. There are 

 plains of still greater elevation, on which, although 

 they have a mean temperature of from 51 '8 to 55*4, 

 equal to that of France and Lombardy, the vegetation 

 is less vigorous, and European plants do not thrive so 

 well as in their native soil. The winters there are 

 not extremely severe, but in summer the sun has 

 not sufficient power over the rarified air to bring 

 fruits to perfect maturity. 



From the peculiar circumstances of New- Spain, as 

 here sketched, the influence of geographical position 

 upon the vegetation is much less than that of the 

 height of the ground above the sea. In the nine- 

 teenth and .twentieth degrees of latitude, sugar, cot- 

 ton, cacao, and indigo are produced abundantly only 

 at an elevation of from 1968 to 2625 feet. Wheat 

 thrives on the declivities of the mountains, along a 

 zone which commences at 4593 feet, and ends at 

 9843. The banana (Musa paradisiaca), on the fruit 

 of which the inhabitants of the tropics chiefly sub- 

 sist, is seldom productive above 5085 feet ; oaks 

 grow only between 2625 and 9843 feet ; and pines 

 never descend lower than 6096, nor rise above 13,124 

 feet. 



Cc 



