ELECTRICITY.

What is it? and what some of its manifestations? The name was given to

an occult, but everywhere present, property of material things. First

discovered by the ancients in amber (Gr. _electron_) and brought into

evidence by friction. It is generally spoken of as a highly elastic,

imponderable fluid, or fluids, with which all matter is supposed to be

in a greater or less degree charged. Though such fluids have never been

discovered as entities, and their existence may be but imaginary, it

was asserted to account for facts that otherwise seemed inexplicable.

Definitions of electricity are at hand, and could be easily given; but

they do not define or accurately point out that which they designate.

All that can be said, with confidence, is that certain phenomena which

come within our observation suggest the presence of such fluids, and

are not otherwise explained. The answer to the question, “What is it?”

must be the honest confession, we do not know. But, if ignorant of what

it is, we may yet intelligently study its manifestations. The phenomena

are not less capable of satisfactory discussion because the efficient

agent producing them is unknown.

The theory of two imponderable fluids or electricities having strong

attractive and repellant forces, is adopted because probable, and it

helps make the discussion intelligible.

The awakened interest now so widely felt in this branch of natural

science is more than just the desire to know what is knowable of the

world we live in. At first, and indeed for ages, only the curious

studied electricity, and practical men asked “_Cui bono?_” But in

the present century it has become an applied science. In no other

field have our studies of nature been more fruitful of discoveries

practically affecting the multiform industries, and improving the

rapidly advancing civilization of the age.

Some of the skillful inventions for controlling and utilizing this

power lying all about us will be mentioned hereafter.

It will be well first to state a few facts that are known and mostly

established by experimental tests:

(1) The earth, and all bodies on its surface, with the atmosphere

surrounding it, are charged with electricity of greater or less

potency. This seems their permanent state, though in some cases, its

presence is not easily detected.

(2) In quantity or intensity it is very different in different bodies,

as also in the same under different conditions. In some portions of

vast objects, as the earth and its atmosphere, it accumulates, immense

currents being poured into them, while others are perhaps to the same

extent drained.

(3) Through some bodies the subtle fluid may pass with but slight

obstruction—and they are called _conductors_. In others the hindrance

is greater, and we call them _insulators_. But the difference is only

of degrees; as the best conductors offer some obstruction, and the most

perfect insulators do not completely insulate. The metals, charcoal,

water, and most moist substances, as the earth and animal bodies, offer

but little resistance. The atmosphere, most kinds of glass, sulphur,

india rubber, vulcanite, shellac, and other resins, with dry silk and

cotton, are our best insulators. Friction used to secure electrical

manifestations is the occasion rather than the cause of the electricity

thus developed or set free. That it does not cause it, even in the

sense that it causes heat is evident, since the quantity of electricity

bears no proportion to the amount of friction used to produce it.

Though, really, there are not several distinct kinds of electricity,

as statical, dynamic, magnetic, frictional, and atmospheric, the

nomenclature of the science is at least convenient, and will not

mislead. It indicates the methods of production, and makes the

discussion of the subject more intelligible. And then the electricity

developed or set free by the different methods of excitement, though of

the same kind, differs much in degree and intensity.

What is called statical electricity is the condition of the subtle

force in a state of electrical quiescence; and all electricity in

motion, however excited by friction, heat, chemical action, or

otherwise, is dynamic.

Perpetual modifications are taking place in electrical condition of all

matter, that when made apparent, at first may seem quite inexplicable.

The excited currents flow with amazing rapidity. Their actions and

re-actions baffle our calculations, and the imagination itself is

bewildered by their extent and complexity. Yet by electrical tests and

laboratory experiments, carefully employed, the laws of electricity are

now as well known as those of any other branch of physical science,

and the phenomena, if more startling, are no more mysterious than the

manifestations of heat, light and gravitation.

Atmospheric electricity is not different in kind from that brought into

evidence by the methods of the experimenter in the laboratory, subject

to his control, and much used in the arts and industries of life. The

lightning that shineth from the one part under heaven to the other part

under heaven, a bright light in the cloud, is the same as the electric

spark from the moderately charged receiver, when the positive and

negative poles are brought into contact—the same as the less intense

spark excited by passing the hand rapidly over the fur on the cat’s

back when the electrical conditions are favorable.

The storm cloud is a vast receiver and by induction becomes at times

highly charged with electricity. If the cloud is at rest, and the

heated air grows moist, that which is known as sheet or heat lightning

appears in frequent flashes. The imprisoned electricity leaps forth

from the bosom or edge of the cloud, but as instantly gathers itself

back to its source, and apparently without tension or force enough

to crash through the atmosphere to any distant object. The flashes

are unaccompanied by the noise of thunder, and may be but reflections

on the cloud from a source far beyond. We watch them without fear of

danger, and the subdued impression is that of the beautiful.

Amidst the terrific grandeur of the violent thunder storm another form

of lightning is seen; either the vivid flash that seems to envelop us,

or zigzag, sometimes forked lines that dash across the cloud earthward,

and occasionally, as in a return stroke, from the earth to the cloud.

In about the middle of the eighteenth century the identity of lightning

with electricity was fully ascertained, and since then the most sublime

and startling phenomena of our thunder storms are better understood.

Under certain contingencies they must occur. Since the different

clouds or portions of the same cloud are charged with different

electricities, positive and negative, when these by the winds are

brought near each other, or rolled together, fierce explosions follow,

and great electrical changes take place in the clouds. Vast supplies

of the imprisoned fiery fluid leap from strata to strata, or, if the

distance is not too great, and the earth is at the same time strongly

electrified, crash down to it through whatever sufficient conductors

are found. If those not sufficient to receive and convey the charge

be in the path they are dashed aside; men and beasts are killed by

the shock, trees and other less perfect conductors are scattered in

fragments.

Usually the more prominent objects as masts of ships, trees, and

buildings are struck in the lightning’s course from the cloud, but

occasionally those lowest down, near trees, and even in cellars receive

the shock. In these cases the current is probably from the earth,

whose electric condition is negative with respect to the clouds that

pass over it. In either case the opposite electricities that strongly

attract each other, and whose concurrence produces the destructive

discharge near the earth’s surface are held apart by the stratum of air

between them. When the attraction becomes too strong to be resisted by

the insulating medium they rush together, in their fiery embrace, the

flash and concussion being in proportion to the intensity of the charge.

Do lightning rods protect? Yes; but not perfectly. If properly

constructed, and of sufficient conducting capacity, they are a source

of safety, and to discard them as useless is not wise.

The instances in which buildings provided with rods have been struck

do not prove them useless; or, as some say, that the rods do harm by

attracting the lightning that they are unable to conduct to the earth

without injury to the building. The point does not attract, but only

catches the electricity that sweeps over it. When violent shocks or

explosions occur the rod may be of little service. Its office is to

prevent these by silently conducting the excess of electricity from

the air. The rod, rightly placed, conducts to the earth all it can,

lessening the evil it does not entirely prevent. But all danger is not

removed. The position of the opposite poles in the immense battery may

be such as to give the stroke a horizontal direction, and far below the

point of the rod; such currents have been known to pass long distances

through atmosphere and smite with destructive violence objects lying

in their path. Against these lateral attacks rods above our roofs are

probably little or no protection. Still the more good conductors there

are in any locality the less danger, as they prevent the accumulation

of electricity.