26 INDIRECT UTILITY OF FORESTS. 



cases, however, two or more agencies were at work at the 

 same time, and the observations were not always sufficiently 

 accurate and direct to decide in how far the produced effect 

 was due to the one or the other cause. The consequence, 

 naturally, was exaggerated confidence and belief on the part 

 of some and doubt and unbelief on the part of others. This 

 led in modern times to the commencement of accurate 

 observations, first by Becquerel in France, and then by 

 Nordlinger and Krutzsch in Germany, who recorded the 

 effects of forests upon temperature and rainfall at stations 

 situated in, or in the vicinity of, forests. A thoroughly 

 practical and conclusive method was, however, not intro- 

 duced until the year 1867, when both in France and 

 Germany, so-called parallel or double stations were started, 

 one being situated inside a fully stocked forest and the other 

 at some distance from its external boundary in the adjoining 

 open country, all other conditions, such as elevation, soil, etc., 

 being as nearly as possible the same in both cases. Ebermayer 

 started seven double stations of this kind in various parts of 

 Bavaria. Switzerland soon followed with three double 

 stations in the Canton Bern ; then Austria, Italy, Prussia, 

 Alsace-Lorraine, Thiiringia, Brunswick, Wiirtemberg, Sweden 

 and others. Similar double stations were started in India 

 (Dehra Dun, Berar, Ajmer). In Cape Colony, observations 

 were commenced about seven years ago. The result has 

 been a rich crop of reliable observations. Although many 

 questions await as yet a final solution, much has been learned 

 and established which it is proposed to indicate in the 

 following pages. The results of the Bavarian observations 

 were published by Dr. E. Ebermayer in his excellent book, 

 "Die physicalischen Einwirkungen des Waldes auf Luft und 

 Boden," and Prof. Dr. E. Weber has subsequently brought 

 together the more important results of all European observa- 

 tions in his Introduction to the second edition of Lorey's 

 " Handbuch der Forstwissenschaft," edited by Dr. Stoetzer, 

 published in 1903. 



