154 
ELECTRICITY AND VEGETATION. 
receive the fluid at the ground, ought to stretch from pole to pole, directly under 
those suspended above ; and from these main wires, or prime conductors, others 
ought to proceed in various directions, especially on dry land." 
In the figure, the round dots at the ends of the black lines indicate the 
, . situations of the four poles ; the black lines theni- 
\ \ / / selves representing the main underground conducting 
--" wires. The secondary dotted lines show the branch 
wires, which are joined to those main cross wires. 
When a stream of electricity passes into a con- 
ductor, whether from the air or from an artificial 
machine, it excites all the particles of which that 
^y""- — conductor is composed : they are all rendered polar ; 
/ \ \ and thus, as in voltaic electricity, an interchangeable 
reciprocating series of attractions takes place, which 
assumes the form of a current : at the same time every exterior particle radiates, 
and communicates the fluid to any surrounding medium. Thus, in the above 
examples given in the figures, the cross wires upon the poles, receiving a charge 
whenever the atmospheric electricity is positive, convey the fluid from particle to 
particle, to the underground series — consisting of the four main, and twelve sub- 
sidiary wires — which then pour forth an electric effluvium, not only from their 
points, but from their entire surface ; so that the ground becomes electrified to a 
considerable extent beyond the boundaries of the wires themselves. 
In dry settled weather the air is generally positive, and then so long as the 
ground shall remain rather free and moist there can be little doubt that a very effi- 
cient supply will be afforded from above ; but as by becoming parched its conducting 
power is greatly lessened, it would be prudent to. bury the ground wires four or five 
inches below the surface, so as to secure the advantage to be derived from some 
moisture retained even during the longest periods of ordinary drought. 
In order to explain the conducting power of soil, its increase during moist 
weather, and its abatement — if not almost total suspension — under an opposite 
condition, we will appeal to an hypothesis, which some may deem extravagant, 
although supported by an experiment rather familiarly known. As it is admitted 
that electric and voltaic electricity cannot decompose any fluid or solid, unless that 
which is termed a current pass into and through it, the converse of the proposition 
is claimed, and our hypothesis requires that the current, or electric stream, shall be 
the inevitable concomitant of decomposition. Water, or ground moisture, is a 
conductor ; dry earth, which is composed chiefly of flinty matter, is the reverse : the 
conducting quality, therefore, is in proportion either great or small. 
Water is decomposable by electro-voltaic action; that is, all and each of its 
particles are electrized, and reciprocally convey electricity from one to the other, 
with a development of the elements, oxygen gas and hydrogen gas. But the con- 
ducting or decomposable condition of water is greatly promoted by a small degree of 
