6o TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



such a great quantity of water. It looks as if the saturation 

 point is not reached for a long time, and that much water 

 passes through the dead covering and mosses before they 

 become saturated. 



In sudden rainstorms the flow per second of the stream in 

 the wooded basin is a third, or at most a half, of that in the 

 poorly wooded basin. The difference would certainly be 

 greater were it not for the steeper slopes of the former, and 

 also were the latter basin not partially wooded. 



When the rains are prolonged, if the preceding period has 

 been dry the effect of the forest is great in retarding the flow, 

 but otherwise it is not. 



However, in any case, a wooded area does not become cut up 

 as much as a bare soil, and the water does not carry away 

 detritus — so that though a forest cannot always stop an inunda- 

 tion it can do much to prevent damage in steep country. 



During drought the stream in the wooded basin never ceases 

 to flow, whereas the other stream may be quite dry for months 

 together. 



The following table, compiled from the observations of 

 thirteen years (1903-1915), is very significant: — 



Daily Floiv in cubic metres of the Streams per square kilometi-e 

 of each Basin. 



For those who can read German, and can face 625 pages, we 

 may note that Engler's book is called Untersuchungen liber den 

 Einfluss des Waldes auf den Stand der Gewdsser, and that it is 

 published by Beer, at Zurich. 



