FISHERIES, GAME AND FORESTS. 



407 



said amounts including, so far as possible, expenses of every sort and kind. The 

 following statement of the actual cost of the work has been compiled from force 

 accounts so kept and from information furnished by the contractors: 



Labor, not including clearing margins, 

 General expense, ..... 



Raw material, ...... 



Interest, ....... 



Payments made or to be made, account clearing. 

 Team work, delivery of cement and supplies, 

 Insurance, ...... 



Freight, ....... 



Barn account, teams owned by contractor, 



Total amount, 



$31,218 



9,601 



18,830 



13,000 

 6,836 



J < 2 35 

 960 



725 



$83,555 



WHY FORESTS CONSERVE STREAM FLOW.* 



We now approach the third division of our subject — the data of stream flow in 

 relation to forests. As stated at the beginning of the paper this subject has been as 

 yet only casually considered in the United States, although abroad the general 

 question of forest influences has been extensively considered, not only as regards 

 run- off of streams, but in its relations to many other questions as, for instance, the 

 relation of the temperature under woods and outside; the determination of rainfall 

 under woods and outside; the influence of the forest floor covering on the humidity of 

 the soil and on evaporation from the same; the amount of evaporation in the forest 

 and without; the quantity of ground water at different depths under woods and 

 outside, with various aspects and under various kinds of trees; the hygrometric 

 condition of the air under woods and outside; the rain and snow reaching the ground 

 under woods and outside; and many other questions have been studied. In the 

 United States, thus far, the foregoing divisions of the subject have, with one or two 

 exceptions, been left untouched, although measurements of stream flow have, during 

 the last few years, been carried on in many places. 



Moreover, the subject has, for the reasons already assigned, attracted considerable 

 attention, and been, in consequence, the object of a great deal of popular writing, in 

 which the most diverse views have been expressed. It has been held that forests not 

 only increase rainfall, but that they increase the total annual flow of streams, at the 

 same time retarding the rate of surface run-off, thereby decreasing the severity of 



* A portion of the following chapters is from a lecture on The Data of Stream Flow in Relation 

 to Forests, before the engineering classes of Cornell University, April 14, 1899. 



