1849.] 



exercised by Trees on CUmaie. 



451 



general fertility of the soil, rapidly, promoting the regrowth of forests 

 on the tracts previously cleared. At the same time I have no doubt 

 that the process of clearing is slowly advancing under these sirkars, 

 and that it may in due time have a certain effect on the climate and 

 apparent productiveness. 



I have been able to procure but little satisfactory information on 

 these subjects from individuals settled in the country, but I have 

 forwarded herewith copy of a letter from the Dewan of Cochin, as 

 also copy of a private note from the Reverend Mr. Mault, of the 

 London Mission Society, who has been settled for the last 30 years 

 nearly at Nagercoil in the south of Travancore, and who has had 

 much opportunity of observation in his visits to his different schools 

 and chapels in the interior. 



It is facts, as the Reverend Mr. Mault observes, however, and not 

 opinions, that are really valuable, but after all, how few are the facts 

 that are procurable : we can obtain little else any where than the re- 

 sult of casual observation and experience : — the remarks even of the 

 celebrated Humboldt appear to be suppoi ted by but few, if any, actual 

 meteorological data. 



On the effect of cutting down forests he observes, that '* they 

 affect the copiousness of springs, not as was long believed by a pe- 

 culiar attraction for the vapours diffused through the air, but be- 

 cause by sheltering the soil from the direct action of the sun, they 

 diminish the evaporation of the water produced by rain." 



" When forests are destroyed, as they are every w^here in Ame- 

 rica by the European planters, with an imprudent precipitation, the 

 springs are entirely dried up or become less abundant." — Personal 

 Narrative, vol. 4, p, 143-4— and 



Again " with the destruction of the trees, and the increase of the 

 cultivation of sugar, indigo, and cotton, the springs and all the na- 

 tural supplies of the lake of Valencia have diminished from year to 

 year." Vol. 4, p. 144. 



No meteorological observations, however, are given in support of 

 these conclusions, at least not in the Personal Narrative. 



Monsieur A. Moreau de Jonnes, a Staff Officer in the Army of Bel- 

 gium, obtained about the year 1828 a prize for an essay on these sub- 

 jects, from the Philosophic Society of Brussels. He maintained: 



1st. That " the clearing of woods makes the temperature of coun- 

 tries warmer." 



roL. XT, :>:o. jiiti. El 1 



