50 C. A. SCHENCK. 



The Tuckaseegee river is the larger river; it shows, never- 

 theless, slightly greater fluctuations in its discharge than does 

 the Davidson river. The discharges, in the case of the Davidson 

 river, are more even than the discharges of the Tuckaseegee river. 

 It must be admitted, however, that the influence of the forest, 

 or, rather, of a fair measure of soil protection shown at Davidson 

 river, is not very pronounced ; it is slight, and the relative diffe- 

 rences in the discharges of the protected and of the unprotected 

 stream can be expressed by a small percentage. 



The following factors tend to influence the rapidity, if not the 

 amount of water running from the forest-clad watershed : 



1. The greater porosity of the forest soil increases its per- 

 meability; the water precipitated from the clouds sinks into forest 

 soil easier than into field soil. 



2. The litter on the ground, in the forest, checks the super- 

 ficial run-off of water. 



3. The litter and the debris on the ground act as a sponge. 



4. The melting of the snow is retarded under a dense forest 

 cover. If the forest soil is frozen before snow-fall, and if there 

 has been accumulated in the forest on such frozen soil a large 

 quantity of snow, then, indeed, this retardation of the melting 

 process may become disastrous at a time in spring, when the 

 south wind causes the snow to melt rapidly. 



5. The evaporation from forest soil in summer is reduced. 



Floods cannot be avoided; and disastrous floods will occur 

 as often as the atmospheric constellations are such as to bring 

 about in the various headwaters of the various tributaries of 

 a main stream heavy rain-falls, timed in such a manner as to 

 arrive, discharged by the tributaries, simultaneously in the main 

 channel of the stream. 



If the gradient of the streams at their headwaters were smaller 

 than the gradient or fall of the streams in their lower courses, 

 inundations would be rare.' Unfortunately, all over our globe, 

 the opposite is the case. The rivers are fed, like the gutters on 

 the roofs, from steep slopes ; and the fall of the rivers forming 

 the gutters is very gentle. 



Geologically there is no doubt but that floods and inundations 

 were much more formidable in former geological periods than 

 they are in the present era. 



