78 PHYSICAL GEOGRAPHY OF THE SEA. 



of wind and weather. This paves the way for a more vigorous 

 and fortunate offspring ; and as every year adds something to 

 the vegetation on the mountain's side, and opposes increasing 

 obstacles to the winds, the falling leaves and decaying herbage 

 accumulate more and more, until dwarfish trees first find a 

 sufficiency of soil to root upon, and finally, the proud monarch 

 of the forest spreads out his powerful arms and raises his 

 majestic summit to the skies. 



While Greece and Asia Minor have seen their fertility de- 

 crease or vanish with the trees that once covered their hills, 

 other countries have improved as their vast woods have beer, 

 thinned by the axe of the husbandman. In the time of the 

 Bomans all Germany formed one vast and continuous forest, 

 and its climate was consequently much more rigorous than it 

 is at present. All the low grounds were covered with imper- 

 vious morasses, and the winter is described by historians in 

 terms like those we should employ to paint the cold of Siberia. 



But the scene gradually changed as tillage usurped the sylvan 

 domain. The excessive humidity of the soil diminished, the swamps 

 disappeared, and the heat of the sea, penetrating into the bosom of 

 the earth, developed its productive powers. Thus the chestnut 

 and the vine now thrive and ripen their fruits on the banks of 

 the Ehine and the Danube, where 2000 years ago they could not 

 possibly have existed. But Germany would also see her fertility 

 decline, if the destruction of the forests which still crown the 

 brow of many of her hills should continue in a considerable 

 degree. Numerous rivulets would then be dried up during the 

 warm season, in consequence of the more rapid descent and 

 thaw of vernal rains and wintry snows, and most likely, refresh- 

 ing summer showers would be far less frequent. Even now 

 the inundations which almost annually desolate the banks of 

 the Elbe, the Oder, and the Ehine, are ascribed by competent 

 judges to the excessive clearing of the forests in the mountainous 

 countries where those rivers originate. These few examples 

 suffice to prove to us the power of man in modifying the climates 

 of the earth, and the vast importance of the study of terrestrial 

 physics. By planting or destroying woods, he is able to compel 

 nature to a more equitable distribution of her gifts. In marshy 

 and low countries, he may remove the surperfluous waters by 

 drainage, and increase the productiveness of arid plains by 



