APRIL, 165 



where tillage is impracticable, promotes to a high degree both 

 the agricultural and manufacturing interests of individuals, as 

 well as the physical soundness and productive resources of 

 extensive cou)itries. It appears that the influence of forests 

 in a physical, economical, and hygienic point of view, is de- 

 serving of a more complete investigation than it has yet re- 

 ceived. By felling trees which cover the tops and sides of 

 mountains, men in every climate prepare at once two calami- 

 ties for future generations — the want of fuel and the scarcity 

 of water." 



These facts seem to demonstrate that trees on elevated 

 situations have a greater influence as conductors of electricity 

 and causes of showers, and that their benefits are proportional 

 to their elevation. And we may well regard it as one of the 

 instances of the beneficence of nature, who has so arranged 

 it in her economy, that trees should be the most serviceable 

 in those situations which are of the least value for the pur- 

 poses of grazing and tillage. A forest consisting of those 

 trees which, like the oak, extend a tap root deeply into the 

 soil, may be compared to so many hydraulic rams conveying 

 water from the depth of the soil, and afterwards exhaling it 

 into the atmosphere. It seems to me, therefore, an incontro- 

 vertible point, that one of the most available means of pre- 

 venting summer droughts is to preserve the forests on all our 

 lofty hills and barren elevations, and on all sandy plains, and 

 to cover all such places as are already bald, with trees of the 

 most valuable species. 



There can be no doubt that many a rain cloud migiit be 

 arrested, when passing over a tract of country, by means of 

 lightning rods, attached to the tallest trees in the most elevated 

 places. These rods would conduct the electric fluid from the 

 passing cloud, which would then descend in showers upon 

 that region. It is undoubtedly attributable to the rods and 

 spires and chimneys of a large city that showers are more 

 frequent and abundant there than in similar open situations in 

 the country. I allude to the efl^ect of lightning rods in this 

 connection, not to recommend the use of them, but to illus- 

 trate more clearly an important principle of meteorology. 



