268 CENTRAL AMERICAN FORESTS. 



constant rains at the equator. If these rains were to 

 cease to fall, and the land was to become parched by 

 the intense solar heat, which would certainly follow 

 that catastrophe, there can, we think, be little doubt 

 that the great equatorial forests would wither away 

 and perish. So also, if these abundant rains were by 

 some combination of causes, carried up into the region 

 of the great bush country, they would carry the equa- 

 torial forest growths with them. 



This is exactly what occurs in Central America. A 

 glance at the map will show how narrow the continent 

 is at that point ; and the vast expanses of ocean, which 

 stretch forth from its shores on either side. 



Now, the prevailing set of the trade winds are from 

 the North East; these winds blow, with marvellous 

 regularity, for many months throughout the year, and 

 arrive upon the Central American coasts surcharged 

 with watery vapour, gathered in their passage across 

 the ocean. The next fact to be observed is, that all 

 through Central America a lofty range of mountains 

 forms the back-bone of the continent there. It is 

 known among the Spanish speaking people as the 

 Sierra Madre. These mountains necessarily cause an 

 upcast draught to take place, and thus the water-laden 

 winds are driven upwards into a colder atmosphere, 

 which at once condenses a great part of their vapour 

 hence the damp, moist heat and abundant rainfall 

 of these regions. The formation of clouds prevents 

 the rapid radiation of heat by night, and thus a high 

 temperature is constantly kept up. The luxuriant 

 equatorial forest growths therefore, following the lead 

 of Nature, have overspread the whole of this country. 

 A great deal of the vegetation is evergreen, but the 



