TREATISE BY HERB WEX, 197 



researches in this study in the two following chapters, in the hope 

 that distinguished collahorateurs in the same calling and men of 

 scientific attainments may prosecute further the researches I have 

 been privileged to commence, and that the results of their study 

 may bring great good to generations yet unborn." 

 \ The chapter which follows is occupied with a discussion of the 

 cause or occasion of a diminution having taken place in the quantity 

 of water flowing in streams and rivers, which he thus concludes : — 



" When we fully realise what is implied in the opinions expressed 

 by jnen of science, and practical men expert in such matters, in 

 various countries and in very difierent parts of the world, after long 

 experience, observation, and research, we find that forests affect to a 

 very great extent the quantities of water coming from springs and 

 flowing in rivers ; that they affbct the climate ; and that they have a 

 great effect upon the fertility of the lands in which they exist ; and 

 that thus : — 



" 1. The deposit of rain from the atmosphere is greatly increased 

 by the amount of woods in a district, in as much as mists and clouds 

 passing along" the surface, striking upon the forests, have the moisture 

 of which they are formed condensed and precipitated as rain. 

 Further, the temperature within the woods is cooler by day, and, on 

 the contrary, warmer by night than it is in the open fields and 

 meadows ; and by reason of this, there is a continual cii'culation of 

 air in the vicinity of forests whereby mists and clouds are precipitated 

 and led to discharge themselves of their contents. This happens not 

 through the forests in and for themselves, nor as a consequence of 

 the forests of themselves, but through the difference between the 

 forests and the open fields ; and on this depends the abundance of 

 the rain. It is also very manifest that the forests exercise an 

 attractive influence upon the clouds, by their attracting from them 

 electricity with which they are charged, and with this the water of 

 which they are composed, increasing thereby the rainfall. It is also 

 an ascertained fact that a great part of the water precipitated as rain 

 remains on the leaves of the trees, one part of which falls to the 

 ground, but another portion of which evaporates into the atmosphere, 

 and is again precipitated as fog, mist, dew, or rain, — whence it comes 

 to pass that rain water is kept longer within forest lands, and may be 

 precipitated oftener than once, whereby the rainfall is increased. 



" 2. Through the abundance of forests will the copiousness of the 

 subterranean drainage flow, and springs be increased, while the rain 

 water retained by the foliage of the forest trees, falling slowly to the 



