78 PIYSICAL GEOGRAPITY 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 
Romans 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 Rhine 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 Rhine, are ascribed by competent 
judges to the excessive clearing of the forests in the mountaimous 
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 
