212 EFFECTS OF FORESTS ON SPRINGS AND RIVERS. 



early and effectual measures to provide against the injuries that might 

 soon follow a further neglect of interests in this regard. 



Sect. IV. — Immediate Action of Trees in Arresting the Flow and 

 Escape of Rainfall. 



While it is true that the rainfall is only the precipitation from the 

 air of a quantity of moisture which it could no longer hold in solution, 

 it is no less true that thus often a much larger supply of moisture is 

 brought to a locality than it would have obtained in the same 

 time, or in a much longer time, either by deposit of dew, or by the 

 attraction of moisture from the atmosphere by any of the constituents 

 of the soil; and we have now to consider the immediate effect of 

 trees upon it when thus precipitated. Some of these have been 

 adverted to in documents which have been quoted ; but they require 

 more detailed consideration. 



The testimony which goes to show that the destruction of forests 

 has occasioned the drying up of springs, and that the replanting of 

 woods has been followed by their re-appearance, seems to be incon- 

 trovertible ; but it has been questioned whether the views which 

 have been advanced and have been generally received in regard to 

 some of the phenomena connected therewith be correct. 



Marshal Vaillant, whose experiments on the emission of moisture 

 from the leaves of trees have been cited in a preceding chapter, 

 remarks : — " In the report read by Monsieur Becquerel, at the 

 Academy of Science, it is asserted that sprinc/s genercdly have their rise 

 in mountains. It is true, and according to nature, that the causes 

 which formed the mountains have at the same time broken up the 

 impermeable strata in which are stored the water which creates and 

 supplies the springs. That forests are more usually formed on 

 mountain declivities than in the plains is generally true, and this is a 

 simple consequence of the superior fertility of the plains and valleys, 

 and of the greater trouble which the agriculturist would have in 

 cultivating such difficult localities where there are often not even 

 forest tracks ; but to conclude from this that there is a necessary 

 and intimate relation between the existence of forests and of springs 

 is perhaps a rather far-fetched conclusion ; and we think it would 

 be well to examine what the conclusion is really worth. 



" The same report states that, ' the roots of the trees by dividing 

 the soil make it more permeable and facilitate infiltration.' 



" May we be permitted to make some observations on this point. 



