22 VOLCANIC FORCES. 



philosophers. But the general fact to which 1 

 would here invite attention is, that the number of 

 volcanos and the forces they exert are in proportion 

 to the heating power of the sun* For example, 

 among the 200 volcanos now in action in different 

 parts of the earth, about one half are confined to 

 the tropical regions. In the island of Java alone, 

 Mr. Lyell says there are thirty-eight : and there is 

 about the same number in other tropical portions of 

 the old world. Between latitudes 10 and 15, in the 

 Provinces of Guatimala and Nicaragua in South 

 America, there are twenty-one; while in Peru, 

 between latitudes 14 and 20, there are sixteen ; 

 and I know not how many in the West Indies. 



Again ; that the subterranean forces by which 

 the dry land has been elevated from beneath the 

 ocean, have in all past ages been in proportion 

 to the heating power of the sun, would appear 

 from the relative heights of the earth in different 

 latitudes. Nearly the whole of tropical America 



* In every point of view, a complete theory of volcanos is of 

 fundamental importance: for they regulate the distribution of 

 land and sea, the magnitude and elevation of continents, the 

 diversities of temperature in given latitudes, the character of 

 rivers, and modify the direction of winds, which are impeded 

 or deflected by mountain ranges. They are also the great ter- 

 restrial laboratories in which most of the precious gems are 

 formed, in which carbon is liquified, and by slowly cooling under 

 an immense pressure, assumes the crystalline form of that beau- 

 tiful ornament the diamond, which has been aptly designated as 

 " a lump of light." Nor is it unworthy of notice, that all the 

 richest gems and metals have been found in greatest abundance 

 in the tropical mountains, or among the materials washed down 

 from them by rains, rivers, and springs. 



