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much occurs without giving any evidence that can be appreciated by our five senses. When a wire is tapped here and there and a part of the electrical energy is translated into some other form that we recognize, such as light or heat, it seems an unreasonable and miraculous occurrence, for with our limited perceptions we cannot follow from cause to effect. When a little familiarity with the phenomena is acquired we are apt to forget the miraculous part just as we do on seeing an object drop toward the earth. We become content simply to give a name to the force. It seems to bring electricity nearer when it is thought how little we should know about heat for instance, if there were no sense of feeling. A good deal could be learned about it in a slow way, but its actions would be very mysterious. We should, perhaps, see a piece of wood suddenly blaze up, and a kettle of water a foot above it begin to dance about and boil, and yet we might pass our hands between the fire and the kettle with no appreciation of anything happening there. Steam might be carried from a closed kettle through a pipe to a small engine. The pipe might be of glass and nothing would be seen, so if we had no sense of feeling we should see only a piece of wood blazing, and a machine, with no apparent connection, doing work. This would surely not be less mysterious than the working of an electric motor.

Electricity is not an erratic, uncertain thing. The laws that govern electrical forces are well known, the forces can be controlled without great trouble, they can be measured with the greatest accuracy, and the way they will act under given conditions can be definitely foretold. Whatever electricity really is and whatever may ultimately be found true with regard to its nature, it is known that it acts very much as if it were a fluid, and all the actions of water flowing in a pipe are closely analogous to electricity "flowing" in a wire. We cannot go very far wrong when we look upor it in this way, and as water flowing in a pipe is such a familiar phenomenon, a great number of useful analogies are at hand, and an easy way is open to understand many of the actions of electric currents.

In the earlier days of electricity, when trained workmen were scarce and the needs were not so well understood, and when, it might be added, the underwriters were not so hard upon the heels of the contractors, there was a great deal of exceedingly poor and slipshod work done. Electricity was fast getting the reputation of being most untrustworthy, if not actually dangerous. This idea is being dispelled under the improved conditions, and although much bad work is still done and most of the wiring is far from perfect, still it has been proved that even in the most difficult places, electricity can be employed with the greatest surety of action and

freedom from danger. The underwriters have done much to bring about the improved state of affairs, for surety of action and freedom from fire causation are very closely related.

Faulty circuits are not always easily discovered, for there is often no sensible evidence of defects until they are looked for with great painstaking or until they suddenly become worse and give sensational notice of fault. It is consequently of great importance that the work be done thoroughly at the start. It is not a difficult matter to confine electricity to its proper conductor, but to do so it is absolutely necessary that every care be taken with the insulation. With all metals such good conductors, and with brickwork, plaster, and damp wood conductors in some degree, there is great liability that the current will go astray. It is common to compare a current of water with a current of electricity, but there is one striking differWater flows freely in space, and to conduct it we surround a certain amount of space with metal we use a pipe. The metal is the insulator through which the water cannot pass unless the metal be punctured. Electricity does not "flow" freely in space, but does through metals. Space is the impassable and the metal is the "hole." When wires are strung it may be looked upon as punching holes for the electricity to flow in, and if these "holes" are not surrounded by

ence.

some non-conductor it is of course impossible to keep the electricity in the path intended for it. Pipes are strengthened and joints are looked after with regard to the pressure upon them. Electrical insulation should also be looked after with regard to the pressure which it is to withstand, for there is an electro-motive force that is analogous to water-pressure. In insulating wires the difficulty comes from the fact that electric insulators can be either punctured or permeated by conductors. Sometimes the insulators themselves become conductors through the action of heat or other deteriorating agents, and it is thus necessary to provide, in one way or another, against a number of accidents. If a nail pierce the insulation, if dampness permeate it, or if it become charred by heat, there may be leakage. It is as if a water-system were tapped by small pipes through which the water constantly leaked away, only the waste with electricity is far more subtle and attracts no attention unless, because of the leak, there is a lack of power in the circuit. And it is by no means the waste only that makes leaks undesirable. There is often a very small margin between a small leak and a great one, and if it is large it carries off practically all of the electricity, leaving nothing for useful purposes, and in doing so is very apt to cause a part of the circuit to heat to a dangerously high temperature. But even in damp cellars, tunnels, and mines, electric circuits are in

successful operation. If a few principles are kept in mind and a few rules carefully followed leaks will be impossible under normal conditions.

The strangeness of electrical terms is, perhaps, largely accountable for the lack of knowledge about electrical matters. It is discouraging to meet at the start with "volts," "ampères," "ohms," "watts," and other names and expressions as mysterious as the cabalistic signs on a physician's prescription. But it is only another illustration for Carlyle's "Philosophy of Clothes." Electricity is not the only subject that is looked upon with increased respect and awe because of the peculiar names given to ideas concerning it.

This clothing of the ideas no doubt obscures many simple facts and fails to suggest their semblance to ideas that are familiar, but in the end it is an aid to clearness to have the terms distinctive. When once there is clear conception of the fundamental ideas, the electrical nomenclature is found simple and direct, and it is an advantage to have specific terms that will not suggest too readily, foreign ideas not analogous in all particulars. It is, perhaps, this very directness, the absence of all roundabout terms, that makes most electrical talk sound highly technical. It is encouraging to the uninformed to meet in explanations with "pounds," "feet," and other common quantities, because they are familiar, and the most abstruse talk in

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