CONTENTS, IX 



elsewhere by Marsh (p. 106); by Hooker (p. 108); by Schleidea 

 and Fries (p. 108); Fraas (p. 109); Becqaerel (p. 110); Laurent, 

 &c. (p. Ill); Humboldt (p. 112); Boussingault (p. 113) ; and 

 Hough (p. lis;. 



Section III, — Cases in which the Destruction of Trees have been 

 followed by desiccation ; and the planting of Trees has been 

 followed by the restoration of humidity, - - 117 



St. Helena fp. 117) and the Mauritius (p. 124) are adduced as cases 

 in which the destruction of trees has been followed by desiccation ; 

 and the replanting of trees with restoration of humidity. The 

 Island of Ascension is brought forward as a case, in which the 

 •absence of trees was accompanied by aridity, and the planting of 

 trees was followed by humidity (p. 128) ; the measures adopted are 

 detailed (p. 134) ; and the successful results are reported (p. 141). 



Section IV. — Cases illustrative of Effects of Forests on 



Humidity corresponding to such as have been adduced, - 144 

 Accounts are given of climatal changes on the Island of Madeira 

 (p. 144) ; and reference is made to alleged changes in Alexandria 

 and in Egypt fp. 146^; South Africa Cp. 148); South America, &c. 

 (p. 149). 



Chapter V. — Local Effects of Forests o7i the Rainfall and on 



Rivers, - - - - - - 150 



Section I. — On the production of Rain, - . . 151 



The production of rain is traced to the deposit of moisture in excess 

 of what can be retained at a reduced temperature by air by which 

 it had been absorbed ; and in view of this there is detailed the rise 

 of the Trade Winds (p. 151), the course of currents of air from 

 the polar to the equatorial regions, and their return thither deposit- 

 ing moisture absorbed while proceeding toward the equator (p. 152). 

 Reference is made to the quantity which must have been so absorbed 

 (p. 153). The production of clouds by eddies and whirlwinds is 

 described (p. 156) ; and the production of rain as detailed by Sir 

 John Herschel (p. 158). 



Section II. — The Effects of Forests on the quantity of the Local 



Rainfall, - - - - - - 159 



There are brought forward the views of Boussingault and Becquerjl 

 that forests increase the local rainfall (p, 159), Observations by 

 Mr Draper are again brought forward, but with them an illustration 

 of the effect of forests by Coultas (p. 160) ; and statements of the 

 views of Marsh and the observations of Mat hieu in accordance with 

 the views of Boussingault (p. 161); with remarks on the same by 

 M. C6zanne (p. 162). 



