134 SCIENTIFIC AGRICULTURE. 



upon future generations two calamities at once, a want of 

 fuel and a scarcity of water." [Humboldt.] 



The rainy season is less regular in countries where the soil 

 is dry and naked, than where it is moist and covered with 

 dense forests or luxuriant vegetation. In some parts of South 

 America, which are clothed with ancient and large forests, rain 

 is falling almost incessantly : but in the same country, where 

 there are wide extended plains and little vegetation, it seldom 

 or never rains. Boussingault states, that when he was in 

 Payta, in South America, the inhabitants informed him it had 

 not rained there in seventeen years. The conclusions to which 

 he arrived on this subject, part of them sustained also by 

 Humboldt and Dr. Hitchcock, are as follows. 



1. "That extensive destruction of forests lessens the quan- 

 tity of running water in a country. 



2. " That it is impossible to say precisely whether this dimi- 

 nution is due to a less mean annual quantity of rain, or to 

 more active evaporation, or to these two effects combined. 



3. " That the quantity of running water does not appear to 

 have suffered any diminution or change in countries which 

 have known nothing of agricultural improvement. 



4. "That independent of preserving running streams, by 

 opposing an obstacle to evaporation, forests economize and 

 regulate their flow. 



5. "That agriculture established in a dry country, not 

 covered with forests, dissipates an additional portion of its 

 running water. 



6. "That clearings of forest land of limited extent may 

 cause the disappearance of particular springs, -without our 

 being therefore authorised to conclude that the mean annual 

 quantity of rain has been diminished. 



7. " That in assuming the meteorological data collected in 

 intertropical countries, it may be presumed that clearing off 

 the forests does actually dimmish the mean annual quantity 

 of rain which falls." 



