INFLUENCE OF FORESTS ON CLIMATE. 11 



the most rapid departure of all the water that may fall in 

 the form of rain. A few showers at a certain season^ may 

 produce a great amount of water, and still the section be 

 so dry as to be almost uninhabitable the remainder of the 

 year. One-half the quantity of water, if distributed 

 through a longer period, might be all that was actually 

 necessary to make the soil fertile and the climate de- 

 lightful. 



In many instances the destruction of large forests ap- 

 pears to have diminished the amount of rainfall, while in 

 others no diminution has been observed. Col. Plavfair, 

 British Consul for Algiers, in a report to the home Gov- 

 ernment, instances some remarkable effects of extensive 

 destruction of forests in that country. " During the 

 first twelve years, since 1838, from which time meteoro- 

 logical observations have been carried on in Algiers, the 

 rainfall averaged 32 inches annually. During the sec- 

 ond twelve years it had decreased to 30.8 inches, and 

 during the last fourteen years, it has been but 25. 5 inches. 

 The decrease became apparent after the principal clear- 

 ings of wood in 1845, and in 1876 so exhausted had the 

 soil become, that a famine seemed imminent in Western 

 Algiers.^' 



Similar instances in the decrease in the amount of rain- 

 fall following the destruction of forests, have been re- 

 ported by several observers in various parts of the world, 

 but principally by those residing in hot climates. AVher- 

 ever forests of any considerable extent have been de- 

 stroyed in Australia, Africa, India, Ceylon, or in the is- 

 lands of the Indian and Atlantic oceans, lying within 

 what may be termed the tropical belt, drouths seem to 

 have almost invariably f ollow^ed. These drouths, however, 

 have not in all instances been traceable to a diminished 

 amount of rain, but to rapid dispersion of moisture by 

 winds, as well as evaporations from a soil exposed to the 

 direct rays of a tropical sun. In fact, all written history 



