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entirely destitute of rain. This is the case along an extent of 

 several hundred miles of the coast of Peru, and many other parts. 

 At Cumana, on the north coast of South America, the annual 

 quantity of rain is scarcely 10 inches ; and there are other places 

 on the shores of that continent where none falls for several 

 years, but where, nevertheless, vegetation is exceedingly luxu- 

 riant, owing to the humidity of the atmosphere. 



In Santa Ana, on the central Cordillera, at an elevation of 

 3648 feet above the level of the sea, mean temperature 75° 5 lati- 

 tude 5° 10' north, no rain falls for months together, yet the air 

 is so strongly saturated that vegetation (excepting the plains 

 below) flourish in their usual luxuriance. In the torrid zone, 

 generally, the temperature ranges within comparatively small 

 limits, and the various phenomena of the atmosphere occur from 

 one year to another with a regular and uniform succession un- 

 known in this part of the world : the dry and rainy seasons are 

 the divisions of the year, depending on the position of the sun 

 and elevation. 



The subject of climate is in itself highly interesting ; but it be- 

 comes still more so when w r e extend our view, and consider its 

 effects upon the numerous animal and vegetable tribes which are 

 dispersed over the earth, and compare them with those of the 

 past, which are now entombed in our rocks. 



Every climate, as we pass from the plains just raised above 

 the level of the ocean to the curve of congelation, has its pecu- 

 liar vegetation. At the equator palms flourish within the zone, 

 varying from 80° to 70° of mean annual temperature ; but on 

 ascending to the elevation of 4000 feet above the level of the 

 sea, to a mean temperature below 'JO , they almost cease to 

 grow ; however, a few isolated groups of particular species con- 

 tinue to flourish at a higher elevation in New Grenada. On 

 ascending to the elevation of about 5000 feet the arborescent 

 ferns cease to grow, and in the next zone (above) the vegetable 

 tribe of the hot region disappears, and new varieties make their 

 appearance, such as the oak, firs, and several others common in 

 the temperate zones. Near the equator the oak grows at an 

 elevation of 9200 feet above the level of the sea, and never de- 

 scends lower than 5500 feet. It therefore follows that if the 

 whole of the land within the tropics were to be elevated to 8000 



H 



