at) 



INDIRECT UTILITY OF FORESTS. 



be greater than that of open air, more especiallj^ in summer. 

 The following data will illustrate this : — 



The Bavarian observations of 1868-69 gave the subjoined 

 results, as a general average : — 



These observations show that the mean annual excess 

 amounted to 6'36 per cent. There was, however, a decided 

 difference according to the altitude of the stations. While 

 the excess amounted to only 3'14 per cent, at 1,066 feet above 

 the sea, it was as much as 8-79 per cent, at 2,956 feet eleva- 

 tion. Further differences have been recorded according to 

 the species as the following data will show, representing the 

 averages of the German observations : — 



Evergreen, dense spruce woods i)roduced a much greater 

 effect than the thin crowned Scotch pine, or the deciduous 



