288 GENERAL VIEWS, 



weight of the load, and sinks to the bottom of the wa- 

 ter. These appearances are by no means uncommon 

 in the north of Europe. The effect they hare in chang- 

 ing the face of the soil is greater or less according to 

 circumstance?, and in certain districts they may even 

 affect perceptibly the temperature and quality of the 

 atmosphere ; but scarcely beyond the spot where they 

 take place. Jn regard to forests, however, the case is 

 very different ; their influence is felt far around. Their 

 usual effect is to'cool the atmosphere, to a greater extent 

 even than the degree of latitude. When France and Ger- 

 man} r were covered with wood, Europe was much colder 

 than at present ; the winters of Italy were longer ; the 

 Vine could not be cultivated on this sidejof Grenoble ; 

 the Seine froze every year. The parts of the coast of 

 Cayenne which have been cleared of their wood by 

 Europeans, experience in summer in its full force the 

 overwhelming heat of the sun of the torrid zone, while, 

 in the same season, the interior of the country is cool- 

 ed to such a degree by forests, that a fire or shelter is 

 found necessary in order to pass the night. 



The causes why forests thus lower the temperature, 

 are plain. They detain and condense the clouds as these 

 pass ; they pour into the atmosphere volumes of water 

 dissolved into vapour ; winds do not penetrate into their 

 recesses ; the sun never warms the earth they shade ; 

 and the soil being porous, as formed in part of the de- 

 cayed leaves, branches, and stems of trees, and coated 

 over besides by a thick bed of brushwood and moss, is 

 constantly in a state of moisture. The hollows in them 

 serve as reservoirs for cold and stagnant waters, their 

 declivities give rise to numberless brooks and rivulets ; 

 and, as we see, the best wooded countries are ever 

 those which are watered by the largest rivers. 



