58 BOARD OF AGRICULTURE. 



from them. It remains now to speak of the cause of droughts, 

 and the means of guarding against them. 



There can be no doubt, as already intimated, that the de- 

 struction of our forests has much increased the severity of our 

 summer droughts, and this effect may have been produced with- 

 out any actual change in our mean annual temperature. All 

 growing vegetables, and dense forests in particular, have a ten- 

 dency to lower the temperature of the earth, by the large 

 amount of evaporation which constantly takes place from their 

 leaves, and by protecting the ground against the burning rays 

 of the summer sun. It is a fact well known to every farmer, 

 that deep snows lie much longer in thick forests than in the 

 adjoining open plains. It is also well established by direct 

 experiment, that the temperature of the soil, at the depth of 

 twelve inches, in a forest, in the summer, is no less than ten de- 

 grees lower than at the same depth in an open field adjoining. 



The forests, moreover, play a much more prominent part in 

 producing rains than most persons, at first sight, would sup- 

 pose. This is particularly the case when they stand on hills 

 and elevated ground; in such situations their influence fre- 

 quently extends to a considerable distance. The sources of 

 rivers are found in them ; they also determine the direction of 

 the prevailing winds, and consequently the rains ; hence the 

 importance of protecting the forests which stand on land higher 

 than the surrounding country. 



These are, it is true, but general considerations; but an 

 they explain, to some extent at least, the increase in the 

 frequency and severity of droughts, which must be apparent 

 from the sketch before given, I shall venture to extend them 

 so far as to give place to the remarks of a late eminent French 

 writer, whose statements show that the same causes have oper- 

 ated in the south of France, which is subject to droughts some- 

 what like our own. " The land," says he, " in most parts of 

 France, stripped of the forests which once covered it, now 

 presents a bare surface, which the clouds sweep over without 

 finding any obstacles to arrest their progress and resolve 

 them into rain. The soil, exposed to the rays of a scorching 

 sun, is penetrated to a great depth, the sources of streams 

 have dried up, and the rivers scarcely fill a third of their 



