1857. 



NEW ENGLAND FARMER. 



325 



•will hold good as long as any other potato, and is 

 entirely free from disease. I think them fully equal 

 to the Carters, A SUBSCRIBER. 



Granhy, Mass., 1857. 



For the New England Farmer. 



ELECTRIC AGENCY OF TEEES AND 

 PLANTS. 



BY WILSON FLAGG. 



The highly electric state of the atmosphere and 

 the prevalence of thunder showers, during the sea- 

 son in which vegetation is growing with the great- 

 est rapidity, render it important to ascertain the 

 connection of these phenomena with the growth of 

 plants. Some theorists have supposed that plants 

 when freely vegetating, draw ofi' the electric fluid 

 from the earth and discharge it into the atmo- 

 sphere. It is more probable that the production 

 of the electric fluid is due to direct solar influ- 

 ence ; it may be caused by the action of the sun's 

 rays upon the clouds or upon the earth, or it may 

 ascend from the earth with the heat and moisture 

 that evaporates from the surface. In that case the 

 action of plants may be so far the cause of this 

 electric condition, as they are promotive of increased 

 evaporation of moisture. All plants are imperfect 

 conductors, and must serve to equalize the electric 

 condition of the atmosphere, by presenting an infi- 

 nite number of points, both for the discharge and 

 the absorption of electricity, and their united ac- 

 tion must be immense. Trees differ in this respect 

 from other plants, only by presenting a greater 

 number of points at a greater elevation, where they 

 can act more immediately upon the clouds in the 

 upper regions of the atmosphere. 



This subject includes a great deal of debatable 

 ground, and it must be admitted ihat the most of 

 the theories that relate to the electric agency of 

 trees and other plants, are hypothetical. That a 

 tree is not a perfect conductor of the electric fluid 

 is an e tablished point ; otherwise a growing tree 

 would never be shattered by lightning, which passes 

 through a perfect conductor without leaving any 

 marks. A series of letters published by Mr. Pine, 

 of Maidstone, Kent, in the Mechanic's Magazine, 

 (England,) contains an account of some interesting 

 experiments, made by him and his friend Mr. 

 Weekes, with a view to show the connection be- 

 tween vegetation and the electricity of the atmo- 

 sphere. I shall omit his conjectures in relation to 

 the facts which he communicates, and proceed to 

 give an account of his experiments in his own lan- 

 guage. 



"The vast superiority (he remarks) of vegetable 

 over metallic points, in drawing off and accumulat- 

 ing electric matter is, I conceive, a subject of great 

 interest and importance. A coated jar, having for- 

 ty six inches of metallic surface, was repeatedly 

 charged by the activity of a vegetable point, in 

 four minutes and six seconds, while the same jar 

 charged to the same degree, required eleven min- 

 utes and eigMeen seconds, to free it from its elec- 

 tric contents by means of a metallic point — the 

 points, in both cases, being equidistant. I find, 

 also, that Bennett's gold leaf electroscope is power- 

 fully affected by a charged jar, at the distance of 

 nearly seven feet, when the brass cap of the instru- 

 ment is furnished with a branch of the shrub called 

 butcher's broom, and which I have found of great 



use in my experiments. The same delicate instru- 

 ment, when mounted with pointed metallic wires, 

 is not perceptibly affected, until the charged jar 

 approaches to within two feet of the cap." 



This last fact in Mr. Pine's experiment may be 

 explained on the supposition that an invisible cur- 

 rent of moisture which is constantly Issuing from 

 the surfaces of a growing plant, acts as an electric 

 conductor, in the same manner as if the branches 

 of the ])lant were extended. Had the experiment- 

 er, therefore, exposed his apparatus to a draught 

 of dry air, passing between the branch of butcher's 

 broom and the electroscope, the action of the plant 

 upon the electroscope would have been impaired. 

 If my conjecture be true, it involves an important 

 consideration, which is, that trees, being surround- 

 ed by a sphere of moisture having more or less 

 conducting power, must act at a greater distance as 

 conductors of the electric fluid contained in clouds, 

 than metallic points of equal force. 



"In order (continues Mr. Pine) to try the elec- 

 tric action of a vegetable point immediately upon 

 the atmosphere, Mr. Weekes placed a large street 

 lamp, in an inverted position, mounted with a brass 

 cap, through which passed a stout wire, with a 

 brass knot at its nether extremity, and a pair of 

 pith balls, attached by threads to the wire above 

 the knob. Within the lamp was placed a portable 

 stand, with two metallic discs, one on each side of 

 the wire, and rising to a level with the pith balls. 

 To the summit of the wire he attached a small 

 branch of the butcher's broom. This apparatus I 

 have many weeks past had in daily use ; nor can I 

 express the pleasure it has afforded myself and 

 friends, by its frequent indications of atmospheric 

 electricity ; for armed with vegetable detectors, it 

 has shown symptoms of electricity from the pass- 

 ing of clouds at a great altitude, and under various 

 other circumstances, in which electrometers with 

 metallic points placed by its side gave no indica- 

 tion whatever. This appears to me so decided a 

 proof of the superiority of vegetable conductors, 

 that it admits of no contradiction." 



It would appear from these experiments that 

 plants, and more especially trees, whose branches 

 extend towards the clouds, must exert a powerful 

 agency in drawing down the electric fluid from an 

 overcharged atmospheric stratum, thereby prevent- 

 ing, in a degree, those accumulations that produce 

 thunder-storms. Nature employs this grand vege- 

 table apparatus as one of the means of preserving 

 that equilibrium, either of moisture, or of the elec- 

 tric fluid, which cannot be disturbed without dan- 

 gerous consequences. .Growing plants are con- 

 stantly evaporating moisture with greater rapidity 

 than it could be evaporated from the naked sur- 

 face of the ground which they cover; yet notwith- 

 standing this evaporation, they preserve the earth 

 as well as the atmosphere in a moist condition, by 

 attracting to themselves the visible and invisible va- 

 pors that exist in the air. In the same manner 

 growing plants are constantly discharging electric- 

 ity into the air, while absorbing it from the earth. 

 Yet they likewise act as conductors of this fluid 

 from the clouds to the earth, whenever the former 

 are overcharged. Hence we perceive a perpetual 

 circulation both of moisture and of electricity, kept 

 up between the earth and the atmosphere, through 

 the agency of plants. 



Mr. Emerson, author of the "Report on the 

 Trees of Massachusetts," remarks in relation to this 



