REPORT ON FORESTS. 165 



Raritan. The same effect is. noticed on several other streams, 

 and while it is not always easy to determine whether it is due 

 to the forests or to differences of soil and sub-soil, it appears to be 

 true that the forested catchments generally show about the rela- 

 tive superiority in absorptive power over those largely deforested 

 that is shown by the Passaic over the Raritan. Again, during 

 the four years from 1890 to 1893, inclusive, there were on the 

 Raritan thirteen floods exceeding 8,000 cubic feet per second, 

 one of which reached 23,746 cubic feet per second, while on the 

 Passaic during the same time there were but five such floods, 

 and the highest reached only 11,701 cubic feet per second, while 

 the rain-fall on the two streams shows no corresponding differ- 

 ence. 



On the Delaware the more frequent occurrence of floods 

 since 1835 has been pointed out in a report by Professor Mans- 

 field Merriman, printed in Appendix U — XIX of the Annual 

 Report of the Chief Engineer, U. S. Army, for 1873. (See, also. 

 Report on Water-Supply, 1894.) 



EFFECT ON THE PURITY OF THE WATER. 



It is not easy to prove by analysis or statistics any effect of 

 forests upon the quality of the water in the streams. It must 

 be borne in mind that extensive forests are always attended by 

 a scanty population, and for this reason the waters are usually 

 superior in quality, but it is a matter of common observation 

 that the amount of sediment carried is much less upon a forested 

 stream than when the catchment" is under cultivation. The 

 difference in this respect on our red sandstone streams is 

 especially noticeable. On the cultivated portions the amount 

 of mud carried in suspension is very large, but where the catch- 

 ment is well protected with forests it is much less. 



The same fact may be observed if we compare the well- 

 forested Highlands streams, such as the Pequairnock, Rockaway 

 and Ramapo, with those in the more cultivated portions of the 

 Highlands, such as the Musconetcong and the head-waters of 

 the Raritan. From observation, we are disposed to think that 

 water of the best quality is obtained when the slopes and the 

 higher lands of the catchment are covered with forests, while 



