THE FORESTS OF THE UNITED STATES: 
THEIR USE. 
WHAT FORESTS DO. 
Our industries which subsist wholly or mainly upon wood pay the wages of 
more than 1,500,000 men and women. 
Forests not only grow timber, but they hold the soil and they conserve the 
streams. They abate the wind and give protection from excessive heat or 
cold. Woodlands make for the fiber, health, and happiness of each citizen 
and of the nation. 
The fish which live in forest waters furnish each year $21,000,000 worth of 
food, and not less than half as much is furnished by the game which could 
not exist without the forest. 
The industries which use wood wholly or mainly in manufacture 
represent an investment of over $2,250,000,000 and yield each year a 
product worth nearly $3,000,000,000. 
Forests conserve streams by regulating their flow. Our knowledge 
of the effect of forests upon the quantity of water carried by streams 
is not yet complete. Our knowledge of the effect of forests upon 
_ the regularity of stream flow has an adequate basis of observation 
and record. 
We do not possess complete scientific proof that forests increase 
rain, but known laws governing rainfall and the known physical 
effects of forests lead straight to that conclusion. <A part of the 
falling rain or snow is checked by the tree tops and returned to the 
air by evaporation. But this evaporation is wholly or nearly com- 
pensated for by the smaller evaporation from the soil under forest 
cover than from the soil in the open. The forest soil gives up water 
to the air more slowly than either brush land, meadow land, or 
cultivated fields. 
Both observation and record show fully that forests powerfully 
afiect the manner in which water reaches streams and passes down 
them. The forest floor is a blanket, and like a blanket it will hold 
[Cir. 171] 3 
