80 EFFECTS OF FOEESTS ON MABSHES. 



even than the sunflower. But when we consider the vast perspiring 

 surface presented by a large tree in full leaf, it is evident that the 

 quantity of watery vapour it exhales must be immense." 



Of the moisture thus evaporated and passed into the.atmosphere a 

 very great quantity must have been withdrawn from the soil and 

 dissipated, and thus even a marsh might in course of time be dried up. 



Of this effect let me give one illustration, one which was communi- 

 cated to me by a distinguished agriculturist in Berwickshire, not less 

 distinguished for his knowledge of the science and literature of agricul- 

 ture than he is for the practical application he has made of the know- 

 ledge he possesses. On the farm in his possession, and which has been 

 long in the hands of himself and his family, there is a rising ground 

 at the base of which there was a piece of waste land, which, though 

 not a bog, was characterised by its large and luxuriant crop of rushes, 

 and into which sunk the feet of horses, if not of men, when they got 

 upon it, leaving footprints wet, if not filled with water, and there was 

 adjoining this a corner of enclosed cultivated land which it was 

 attempted to make dry by drains, but the attempt was vain. 



Shortly after 1820 the top of the rising ground was planted with 

 iirs and larch. The plantation covered a space of 20 acres. From 

 this time both the swampy waste land and the enclosed drained but 

 damp land became more dry, and at length became perfectly so. 

 Some forty years after the planting of these trees a furious gale pro- 

 duced great devastation in the plantation, uprooting or breaking over 

 most of the trees and leaving standing only here and there one. The 

 scene was unsightly, and ultimately the whole were felled and the 

 land cleared ; but immediately the low-lying ground became swampy 

 as before, and this was its condition when I visited the locality some 

 eight years thereafter. 



The phenomena were accounted for by my friend and informant by 

 the supposition that there must have been a fissure in the rising 

 ground, from which the water oozed out, formerly and now ; but that 

 the rootlets of the trees, during the growth of these, absorbed the 

 moisture, and though their doing so may have increased the humidity 

 of the atmosphere enveloping the trees, it prevented the percolation 

 of the moisture into the ground below, which was previously so wet ; 

 but the removal of the trees allowed it, in oozing out, to descend to 

 the lower-lying soil as before. 



To this explanation I offer no objection — an examination of the 

 rock alone would enable me to test the correctness of it. At the 



