64 ECONOMICS OF FORESTRY. 



with three pairs of parallel stations, and in 1875 

 Prussia established an investigation, which still con- 

 tinues, with seventeen stations, observations being 

 taken at each on instruments set up within the 

 forest and another set in a neighboring field. In 

 1884, Austria instituted a series of radial stations 

 at which not only the difference of meteorological 

 data within and without a forest, but the influence 

 of the forest on its surroundings, were to be meas- 

 ured directly^ 



Although, by these many and long continued 

 observations, some valuable facts have been estab- 

 lished, and our ideas as to the elements which enter 

 into the problem have been cleared up, the real 

 object of inquiry, namely, whether and how far 

 forests exercise an influence upon climate, cannot 

 be said to have progressed far to a solution, and it 

 is questionable whether the present methods will 

 ever lead to a solution. 



'i^ The reasons for this failure are at least three- 

 fold. Both instruments and methods of meteoro- 

 logical inquiry are as yet unsatisfactory. When, 

 for instance, rain gauges will, according to their 

 construction, the manner of their position, and the 

 character of the wind and rain, during the same 

 storm, register amounts varying from 7 to 40 per 

 cent, we are without any means of applying a con- 

 stant factor of correction, and it would appear that 

 no reliance can be placed on such measurements for 

 the purpose of determining the difference of rain- 



