HYDROLOGY OF NEW YORK 



173 



effect, such as the diminution of rivers and the drying up of 

 streams and springs. Other effects, scarcely less certain, are seen 

 in the occurrence of destructive floods, and of unseasonable and 

 prolonged droughts, with other vicissitudes of climate which it 

 is alleged did not occur when the country was covered with forests. 

 These appear to have been brought about by their removal, and 

 might, in a great degree, be alleviated by the restoration of wood- 

 lands to a degree consistent with our best agricultural interests. 



On the other hand, there are many facts tending to show that 

 the presence or absence and the character of forests are the effect 

 of climate, and that their cultivation generally, or the planting of 

 particular species, is closeh T dependent upon it. These conditions 

 of climate should be understood before forest cultivation is 

 attempted. It is also to be noticed that differences of opinion 

 have been expressed among men of science as to the extent of 

 influence that forests exert upon the climate, and it is quite prob- 

 able that the advocates of extreme theories may have erred on 

 both sides. But where principles depend upon facts that may be 

 settled by observation, there should be no differences of opinion ; 

 and as there is no fact in this subject that may not be verified or 

 disproved, the existence of such differences only shows the want 

 of accepted evidence derived from trustworthy records. 



The interested reader is referred to Dr Hough's report, which 

 may be easily obtained, for an extended discussion on this point. 



Relation of forests to stream flow. The extent of forestation 

 has probably a considerable effect on the runoff of streams. With 

 similar rainfalls, two streams, one in a region having dense 

 primeval forests, the other in a region wholly or partially 

 deforested, will show different runoff. The one with the dense 

 forests will show larger runoff than the stream in the deforested 

 area. In some parts of the State of Xew York these differences 

 may amount to as much as 5 or 6 inches in depth over the entire 

 catchment area. Yet it must be said that this proposition is, for 

 the present, tentative in its character. 



The writer is particular to specify dense forests, because a good 

 deal of discussion has clustered around this point. Of such for- 

 ests, the most effective are those composed of spruce, pine, and 

 other evergreen trees. Where the forest is more or less open to 

 wind and sunshine, its effect, while considerable, is still much less 

 marked than that of dense evergreen forests where the sun seldom 



