169 



Bj experiments, it lias been shown that a living plant erapo 

 rates from one third to one fourth more Avhen electrified, than 

 in its natural state ; so that not only the tree, but its column 

 of vapor, serves as an electrode through -which the positive 

 electricity of the air passes to the earth. Animals, in like 

 manner, bj their profuse evaporation, greater than that of 

 vegetables from their higher temperature, furnish better con- 

 ductors than trees ; in confirmation of this, is the common 

 direction given in our scientific works, to avoid the shelter of 

 trees. The electricity, leaving the worse conductor the tree, 

 selects the better the animal. It may even be lured from a 

 lightning rod of small capacity, by a mass of the same metal 

 ol greater magnitude. 



Some facts furnished by Mr. Warner, before quoted, are 

 here available. 



He writes, "there were apple trees of good size on the 

 North and the South of the barn that was struck, at about the 

 distance of three rods. I have a barn 65 rods west of my 

 house, which has been struck ; the same shock went through an 

 apple tree to a post in a fence some seven feet from the tree, 

 which it split and tore in pieces. I could see no mark on the 

 tree, but it has since died. This tree is 30 feet from the 

 barn. Six rods northerly is wood land ; lightning has struck 

 in these woods. I do not know of any minerals in the land in 

 this vicinity, which would attract the lightning, but the land 

 is rolling and of a strong moist soil." 



In South Abington, an oak was shivered, and a pine was 

 struck ; and another in Reading. In Plymouth, an apple tree 

 was struck. In Exeter, a pine tree w-as cut off, and fell to the 

 earth in an erect position. July 15, a locust was split in 

 Hamilton, 80 rods from Dea. Loring's house. A large elm 

 •was struck in Dedham. 



In every instance of the passage of lightning through trees, 

 brought to the attention of the Committee, the tree has been 

 found to suffer to a greater or less extent. 



If then we find the tree incapable from its conducting power, 

 of defending itself, we should judge that lightning would need 

 little inducement to forsake it for a building in which iron to a 

 greater or less extent is employed; nay, even animals in the 

 vicinity of trees would be exposed to greater danger than 

 in an exposed situation in the open air ; for the tree by its 

 great height would first receive the shock, but Avould not 

 withhold it from an animal within the sphere of attraction. The 



ESSEX INST, PROCEED. VOL ii. 22. 



