186 WATER AND FOREST. 



quantities require about 2 per cent, as much water as the water of 

 transpiration and in additioon thereto. On these figures a coniferous 

 forest, which of all the trees makes the best showing, will give a net 

 increase to the ground storage of about 10 per cent, of the rainfall, to 

 say nothing of the storm water held back until the earth has had 

 time to drink its fill — an important item in itself. 



As a practical illustration of actually observed results, the fol- 

 lowing quotations from a report of the State engineer of New Jersey 

 are most appropriate: 



"We believe it will be helpful to the cause of forestry in the 

 "future if the effects of forests upon stream-fiow are more carefully 

 "and accurately stated. 



"Their effect of holding and preserving the soil upon slopes is very 

 "well known, and besides this they create a mass of humus and ab- 

 "sorbent matter upon the surface which has an effect upon stream- 

 "fiow, and the general evils resulting from de-forestation are a mat- 

 "ter of careful observation and record, so that too much stress cannot 

 "be laid upon the desirability of preserving a proper area of forest. 



"The study of the streams shows that in every case, almost, it 

 "is the watershed on which is the largest proportion of forest which 

 "shows the largest flow from ground water." 



This is a very positive statement, but. being based upon continu- 

 ous gaugings of the streams in question, it cannot be controverted. 



