1884.] LETTERS TO THE EDITOR. 65 



Betters to the Editor. 



EFFECTS OF LIGHTNING ON TEEES. 



SIE, — I am glad to see this interesting subject, but one about 

 which, unfortunately, great ignorance prevails, brought before 

 your readers hy ilr. ]\Iichie. 



Like himself, I have often been puzzled to account for the strange 

 manner in which trees are affected by the electric fluid, there 

 seemingly being no regularity whatever either in the cause of the 

 lightning or its powers of destruction. This is amply proved, as 

 Jlr. Michie points out, by the course of lightning on trees, the fluid 

 sometimes passing along one side of the stem, at others making a 

 spiral twist ; at others it spreads out and covers a considerable 

 surface, while at others it seems as if concentrated in the form of a 

 ball. 



Professor Calladon, of Geneva, a great authority on electricity 

 and meteorology, has ascertained that when lightning strikes a tree, 

 it leaves but very few marks of its passage on the upper and middle 

 parts of the trunk — a peculiarity which he ascribes to thefact of those 

 parts being more impregnated with sugar, a good conductor, than 

 the lower part. As the electric fluid descends to the neighbourhood 

 of the heavier branches where there is less saccharine matter, it 

 tears open the bark, and in many instances shivers the tree. 



It is also stated, on the same authority, that the reason why tlie 

 passage of the lightning on certain trees is circuitous or screw-shape, 

 is that the lightning follows the cells of which the bark is composed 

 lengthwise, and in cei'tain sorts of wood these cells are arranged 

 spirally. A remarkable instance of this occurred here lately, iii 

 which a larch-tree, growing in the centre of one of our largest 

 plantations, was struck by lightning, and partially denuded of its 

 bark for a distance of thirty feet from the gi-ound. After careful 

 examination, I come to the conclusion that the lightning struck the 

 tree close to the ground, and travelled up the stem in a spiral form 

 for thirty feet, at which point the intervention of a large branch 

 caused it to change from the regular course and slide off the tree. 

 A strip of bark fully two inches wide at the base, and gradually 

 tapering to about half that width at the top, was completely removed 

 from the tree, and strewn in shreds on the ground beneath. Strange 

 to say, the wood of the tree was not in the least damaged, nor had 

 the bark removed by the liglitning either a scorched appearance or 



F. 



