INFLUENCE OF THE FOREST ON SPRINGS. 215 



Besides, even admitting that the water from summer rains is so 

 completely evaporated as to contribute nothing directly to the 

 supply of springs, it at least tends indirectly to maintain their 

 flow, because it saturates in part the atmosphere, and at the same 

 time prevents the heat of the sun from di'ying the earth to still 

 greater depths, and from bringing within the reach of evapora- 

 tion the moisture of strata which ordinarily do not feel the effects 

 of solar irradiation. 



Influ&nce of the Forest on the Flow of Springs. 



It is an almost universal and, I believe, well-founded opinion, 

 that the protection afforded by the forest against the escape of 

 moisture from its soil by superficial flow and evaporation insures 

 the permanence and regularity of natural springs, not only within 

 the limits of the wood, but at some distance beyond its borders, 

 and thus contributes to the supply of an element essential to both 

 vegetable and animal life. As the forests are destroyed, the 

 springs which flowed from the woods, and, consequently, the 

 greater watercourses fed by them, diminish both in number and 

 in volume. This fact is so famihar throughout the American 



for the entire territory, not including Aliaska, being thirty-six inches. In the 

 different sections of the Union it is as follows : 



Northeastern States 41 inches. 



NewTork 36 " 



Middle States 40^ " 



Ohio 40 " 



Southern States 51 " 



8, W. States and Indian Territories 39i " 



"Western States and Territories . 30 " 



Texas and New Mexico 24^ " 



California 16^ " 



Oregon and Washington Territory 50 " 



The mountainous regions, it appears, do not receive the greatest amount of 

 precipitation. The average downfall of the Southern States bordering on the 

 Atlantic and the Gulf of Mexico exceeds the mean of the whole United States, 

 being no less than fifty-one inches, whUe on the Pacific coast it ranges from 

 fifty to fifty-six inches. 



As a general rule, it may be stated that at the stations on or near the sea- 

 coast the precipitation is greatest in the spring months, though there are sev- 

 eral exceptions to this remark, and at a large majority of the stations the down- 

 fall is considerably greater in the summer months than at any other season. 



