348 DIVERSITY OF CLIMATE. 
perature is under 62°6°, are named Tverras frias. 
The whole table-land of Mexico belongs to this de- 
scription, which the natives consider cold, although 
the ordinary warmth is equal to that of Rome. There 
are plains of still greater elevation, on which, al- 
though 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 win- 
ters 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 posi- 
tion upon the vegetation is much less than that of 
the height of the ground above the sea. In the 
nineteenth and twentieth degrees of latitude, sugar, 
cotton, 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 subsist, 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. 
The internal provinces of the temperate zone en- 
joy a climate essentially different from that of the 
same parallels in the Old Continent. So remark- 
able an inequality prevails indeed between the tem- 
perature of the seasons, that while the winters re- 
semble those of Germany the summers are like 
those of Sicily. A similar difference exists between 
