46 



PARAGRAPH XVII. 



HUMIDITY. 



The humidity of the air depends more on altitude and proximity 

 to the ocean than on the presence or absence of forests. 



The absolute humidity of forest air, all the year round, is equal 

 to the absolute humidity of field air. The relative humidity, 

 however, is less in the field than in the forest during summer 

 by 10 per cent, during winter by 3 per cent, and during the 

 year by 6 per cent owin^ to the lower temperature of forest 

 air. As a consequence, radiation is checked during the night; 

 sudden changes of temperature are mitigated in the forest; and 

 the forest soil is kept more moist during the summer. 



