376 STATE HORTICULTURAL SOCIETY. 



Atlantic, the other the vicinity of Behring's sea, and the cyclones often come 

 from them. Again a large anti-cyclone usually lies over the central north 

 tropical Atlantic just east of the African coast, and another varies in position 

 from Mexico to our southern states, and the paths taken by our cyclones seems 

 to depend much on these anti-cyclones. The positions, activity and motions 

 of the great northern cyclones, the position and motions of the great semi- 

 tropical anti-cyclones are undoubtedly due to general conditions, relative to 

 the earth as a whole or to itsgeutifal features of distribution of laud and water. 

 They cause the large features of weather and it is evident that they are be- 

 yond the reach of the comparatively small changes caused by man. Whether 

 Michigan were covered with forest, or entirely cleared, would probably make 

 no difference with them; their general features for Michigan would be the 

 same. Indeed we may doubt if the foresting or disforesting of the entire 

 United States or the presence or absence of the great lakes would make much 

 difference with these general features. 



There is however one element of a storm area which seems much dependent 

 on the character of the territory passed over, and that is its intensity. A 

 cyclone, in the limited scientific sense, is an atmospheric condition favorable 

 to rainfall, but whether rain falls or there is only cloudiness without rainfall 

 depends on the intensity of action in the cyclone and this intensity changes 

 from region to region. Not even a cyclone can squeeze rain out of atmos- 

 phere in which sufficient moisture does not exist. Now it is a matter of 

 scientific observation and of practical experience that forests are relatively 

 moist, both because the roots and dead leaves tend to hold the water, pre- 

 venting it from flowing away, and because the tree is a natural evaporating 

 machine, through the thousands of mouths of which moisture is constantly 

 pouring into an atmosphere not already too dry. Hence the cyclone finds in 

 forest air the moisture it needs, and that of its functions which is most ir- 

 regular and uncertain, viz. : that of precipitating moisture, is more probable 

 over forests than over plains, and more probable over grassy plains than over 

 deserts. Tliis entirely agrees with Von Bebber's empirical conclusions III., 

 IV.. XL and XII. In this too we also find one reason for the conclusions 

 which relate the greater frequency of floods in regions which are disforested 

 (conclusions IX., XV. and XVI). The rainfall b^iug more frequent in 

 forest areas is less likely to be so severe as to cause floods. 



But it is especially in the perodic and local features of climate that the 

 forest plays a valuable part. By the covering which it gives the soil the ex- 

 tremes of temperature are much reduced. Just as in the Artie regions they 

 wear clothiug to protect from the cold and in the tropics to protect from the 

 heat, the clothing of forests limits that direct exposure to the radiation of the 

 sun which gives us our hottest days and that re-radiation of heat into space 

 which gives us our coldest nights. 



Again the forest serves as a sort of break water to protect the residents iu 

 or near it from the action of high winds, and they serve as another sort of 

 protector in a much more important sense. They protect and hold the water 

 which reaches them, the shade of the trees protect from evaporation and it 

 occurs but slowly except as rhis occurs through the leaves. Besides, the 

 covering layer of dead leaves serves as a sponge to soak up and keep the water 

 which reaches it, and still more to keep the water which passes into the soil 

 beneath. Ilence the conservation of moisture and that of springs in or near 

 woods, and as they let this water escape only slowly and gradually, hence. 



