22 THE UTILITY OF FORESTS. 



(4) They reduce the temperature of the air and soil and render 



the climate more equable. 



(5) They increase the relative humidity of the air, reduce 



evaporation and maintain a more continuous degree of 

 moisture in the soil. 



(6) They tend to increase precipitation of moisture. 



(7) They assist in regulating the water supply, produce a more 



sustained feeding of springs, reduce violent floods and 

 render the flow of water in rivers more continuous. 



(8) They assist in preventing erosion, landslips, avalanches, 



the silting up of rivers and low lands, arrest shifting sands, 

 consolidate too loose soils and assist the aeration of too 

 firm soils. 



(9) They reduce the velocity of air currents, protect adjoining 



fields against cold or dry winds, and afford shelter to 

 cattle, game and birds. 



(10) They increase the artistic beauty of a country, may, under 



certain conditions, increase its healthiness, and at any 

 rate have a beneficial effect upon the human mind. 



(11) Forests render considerable assistance in the defence of a 



country. 



CHAPTER II.— THE FACTORS OF FOREST 

 PRODUCTION. 



In forestry, as well as in the cultivation of field crops, the 

 factors of production may be arranged under three heads : 

 Natural Forces, Capital and Labour, 



1. Natural Forces. 

 They are represented by : — 



(a) The chemical and physical properties of the soil ; and 



(b) The climate, which depends on the geographical position 



and the local conditions governing the intensity of the 

 sun's rays, and the condition of the atmosphere 

 generally. 

 The summary of these forces is in forestry called the " locality." 



