and Subterranean Water Storage. 79 



obtained from decayed leaves, ranks however at 49 ; and the 

 soil that is clothed with forest will thus radiate heat twice as 

 rapidly as that which is uncultivated and naked. 



In Italy the removal of forest has introduced the scirocco, 

 the effect of which is unfavourable to life of all kinds, and many 

 of the crops have suffered thereby. Near Ravenna a pine forest, 

 extending' for about 22 English miles, being cut down, the 

 scirocco was introduced, but was got rid of when the wood was 

 allowed to grow again. In other parts of Italy, where the wood 

 was cut down during the time of the French republic, to enable the 

 manufacture of iron to be carried on, the result was at once seen 

 in an increased severity of climate, the maize no longer ripening. 

 The forests have since been restored, and the climate is restored 

 also. In Belgium favourable results have been obtained by the 

 planting of trees on the right bank of the Scheldt, where large 

 tracts of land, formerly waste, have been rendered fertile. The 

 produce of the plains of Alsace, in the east of France, has 

 suffered since the forests of the Vosges were removed ; and the 

 centre and south of France has felt the influence of the mistral and 

 other injurious winds only since the forests of the Cevennes have 

 been removed. The cultivation of certain plants and trees has 

 thus become difficult or impossible where it was once easy and 

 natural ; and as this has taken place within the period of history, 

 and has followed the disforesting in every case where observation 

 has been made, there can be little doubt as to the cause. Although 

 it is difficult to verify with precision the extent of these changes 

 of climate where accurate and detailed observations are wanting, 

 still the testimony of experience and the comparison of historic 

 accounts point to such a change in Europe within the last 

 thousand years. These conclusions are fully justified and con- 

 firmed by such tabular statements as exist, and are not contra- 

 dicted by any statements, either of fact or opinion. They 

 tend to show that throughout the north temperate zone the 

 summers are cooler, moister, and shorter than they were for- 

 merly ; and that, on the other hand, the winters are milder, 

 drier, and longer, than when forests covered a great part of the 

 land, and cultivation was the exception, and not the rule. It is 

 certain that the rivers and streams have also undergone change, 

 and that where their course has not been interfered with, they 

 are more irregular now than formerly, passing more frequently 

 into torrents, becoming dried up more frequently, and carrying 

 off more rapidly the heavy rains. 



The influence of forests on rain is well recognised within the 

 tropics and wherever in temperate latitudes there are means of 

 observation. In all wooded and undrained countries the atmo- 

 sphere is permanently humid, the rain and dew fertilise the soil. 



