NOTES. 443 



Whether large or small areas of forest and open fields alter, 

 nating, or what percentage of forest is most favorable, can- 

 not as yet be discussed, since we are not clearly informed 

 even as to the manner and the amount of influence which 

 forest cover exercises. In general we may expect that an 

 alternation of large forested and unforested areas in regions 

 which on account of their geographic situation have a dry and 

 rigorous climate is more beneficial than large uninterrupted 

 forest areas, which would fail to set up that local circulation 

 which is brought about by differences in temperature and per- 

 mits an exchange of the forest climate to the neighboring 

 field. 



More recent experiments tend to modify somewhat the con- 

 clusions arrived at heretofore, and indicate, as has been sug- 

 gested, that the differences in temperature and humidity of 

 woods and of open land that have been recorded are largely 

 to be attributed to variability of instruments and of readings, 

 and to nonconformity of conditions. 



Even the well-planned Austrian experiments have produced 

 neither striking nor consistent results. In 1893 Dr. Lorentz 

 Liburnau concluded that forests did not cool the air of the 

 surrounding country, and that temperature extremes were 

 even heightened in the immediate vicinity of the woods. 

 Concerning humidity, it was found that while with one set of 

 stations this appeared increased by an uncertain trifle through 

 the proximity of the forest, in another set no influence was 

 observed, and in one case the air current from the woods was 

 positively drier at noontime than that of the open country, 

 and even though Lorentz Liburnau is still hopeful in the mat- 

 ter, he felt compelled to admit that a " distance effect " of 

 forest influence was so far not demonstrated. 



Schubert, in 1895 and again in 1897, published results of 

 extensive temperature measurements which point to an entire 

 absence of influence in this respect, the air of the forest being 

 in no case sufficiently cooler to warrant a decision. His ex- 

 periments gave a difference of only 5 F. in favor of the pine 



