95 



elevation. In studies made by Schubert (31) in Silesia a few years ago, 

 the experiments indicated that the rainfall varies with forest cover and 

 altitude as 529 + 0.7S p. + 0.57 a, that is, precipitation varies above a con- 

 stant amount by 0.7S nun. for each per cent, of the surface of the country 

 under forest cover and 0.57 mm. for each meter in altitude. It is further 

 stated that beyond about 50 per cent, of tlie total forest area, forest cover 

 seems to have little additional influence uiwn I'ainfall, so that in Silesi;v, 

 which has about OCO mm. rainfall and 29 per cent, forest cover, complete 

 deforestation would reduce this amount only 5 per cent., and 20 to 80 per 

 cent, additional forest cover would increase it but by 1 per cent. Schu- 

 bert (32) has also presented data for the provinces of West Prussia and 

 I'osen and this data corresponds closely with that compiled in Liberia and 

 Sweden. "Correlating these three series of data it may be stated gener- 

 ally that at altitudes under 500 meters an elevation of 100 meters increases 

 the rainfall by S-12 per cent. — the higher tigure for the drier region — 

 while in a country averaging 1.5-25 per cent, forest an increase of 10 per 

 cent, in the forested area gives a corresponding increase of 1-2 per cent, in 

 rainfall." Near Nancy, France, observations were made for seven years 

 in two stations, one in a forest and .the other in an almost woodless country. 

 The results were as follows: 



Excess in Forest. 



February to April 7 per cent. 



May to July 13 per cent. 



August to October 23 per cent. 



November to January 21 per cent. 



Mean of year 16 per cent. 



This shows an increase of 16 per cent, at the forest station. Even 

 this, however, cannot be taken as entirely conclusive proof because other 

 factors may have helped to produce the difference. Willis L. Moore, Chief 

 of the U. S. Weather Bureau, says : "The records of precipitation of the 

 United States Weather Bureau do not show that there has been any ap- 

 preciable permanent decrease in the rainfall of any section of the United 

 States." It should be said of the statement of Moore's that this conclu- 

 sion was given in a pai^er pi-epared to prove that the removal of the for- 

 este has not influenced the erosion of the surface of the ground or the 



