and Nations on the extent and situation of Forests, 255: 



those atmospheric elements which assist in fertilizing the 

 country ; or, finally, by originating that rich humus, which, 

 being so beneficial to the growth of plants, provides the peo- 

 ple with food, the trades and manufactures with raw mate- 

 rials, and commerce with the articles for barter. 



In mountainous but woodless countries, dislocated masses; 

 of soil carry desolation down to the valleys ; torrents of rain; 

 remove and detach from the rocks the loose and fertile mould, 

 and deprive the mountain slopes, thus exposed in all their 

 gloomy nakedness, of the share they had in the irrigation of 

 the plains. The forests extending along the sea-coast^ by in- 

 terlacing their roots with the sand and alluvial soil, help to 

 render it more compact ; they also assist in arresting the mud, 

 deposited by rivers, and in forming the so-called deltas at the 

 estuaries of these latter : thus, a girdle of palm-trees, stretching 

 along the w^estern edge of the valley of the Nile, prevents the 

 fertile plains of the latter from being buried by clouds of 

 Lybian sand, and protects agriculture against the masses of 

 flying sand, drifted about by the blasts of whirlwinds. Large 

 plantations are now acting as a check to the sands blown 

 about on the plains of Gascony, and have laid the founda- 

 tion for an increase of fertility never anticipated. In the 

 larger countries of Europe, even in many parts of Germany, 

 there occur instances of the beneficial influence of plantations. 



Forests occasion the condensation of atmospheric vapours, 

 convey nourishment to the springs, brooks, and rivers, and 

 send moisture to the fields ; they also render the climate 

 more settled, and ward 03" from the crops whatever injury 

 might arise from sudden and violent changes in the weather. 

 By depressing the temperature, they prove, according to 

 the localities, elevations, and degrees of latitude, either 

 beneficial or injurious, and they constitute the chief cause that 

 a woody country, the temperature of which stands, by their 

 means, 1° or 2° R. lower than that of a corresponding wood- 

 less country, assumes the same physical aspect as if it occupied 

 a situation 1-2° latitude farther north, or 224 toises of greater 

 altitude ; hence we conclude, that forests cannot but in- 

 tensely afi^ect the productiveness, the physical condition, 

 and agricultural interests of a country. They establish, if 



