Part 4 (1/2)

MAGNETS AND MAGNETISM--Having described a net that is nets generally The ordinary, pernet, natural or artificial, has little place in the arts It cannot be controlled In coreatest value of netism, as connected with electricity, consists in the fact of the intinet may be made at ith the electric current, as described above A little later we shall see how the process net be made to produce the netisnet_ conetic iron ore) seenet, as made and used in early experiments and still common as a toy or as a piece in some electrical appliances, is a piece of fine steel, of hard te had a current passed through or around it, and soular property of a net is that it may continually impart its quality, yet never lose any of its own Steel alone, of all theits property of being a netized A ”horseshoe” net bent into the fornet has two ”poles”--the positive, or North pole, and the negative, or South pole If anyas one piece two poles only, be cut into two, or a hundred pieces, each separate piece will be like the original net and have its two poles

The law is arbitrary and invariable under all circumstances, and is a law of nature, as unexplainable and as invariable as any in that nets, when suspended by their centers, turn their ends to the North and South, a fa the ordinary conetisnet The pole of the net which points to the North is not the North pole of the needle as we regard it, but the opposite, the South

No one can explain precisely why iron, the purer and softer the better, beconet under the influence of the current, and instantly loses that character when the current ceases, and why steel, the purer and harder the better, at first rejects the influence, and comes slowly under it, but afterwards retains it pernetic netic that are better than they as _conductors_ of the electric current In a certain sense they are also the electric metals A Dynamo, or Motor, made of brass or copper entirely would be inetisoes to make up the field of industrial electric action, would be impossible without the indispensable of ordinary iron, and for the sole reason that it possesses the peculiar qualities, the affinities, described

There is now an understanding of the electro-net, with some idea of the part it may be made to play in the movement of pieces, parts, and machines in which it is an essential It has been explained how soft iron beconet, not necessarily by any actual contact with any otherplaced in an electric field It acquired itsin_ (since that is theof the term) the electricity that was around it But induction has a still wider field, and other characteristics than this alone So a simple case, in which I shall ask the reader to follow me

[Illustration: DIAGRAM THEORY OF INDUCTION]

Let us iine a wire to be stretched horizontally for a little space, and its two ends to be attached to the two poles of an ordinary battery so that a current h it Another wire is stretched beside the first, not touching it, and not connected with any source of electricity Now, if a current is passed through the first wire a current will also show in the second wire, passing in an _opposite direction_ from the first wire's current But this current in the second wire does not continue It is aonly at the h the wire attached to the poles of the battery After this first instantaneous throb there is nothing more But now cut off the current in the first wire, and the second ill show another impulse, this time in the _same direction_ with the current in the first wire Then it is all over again, and there is nothing more The first of these wires and currents, the one attached to the battery poles, is called the _Primary_ The second unattached wire, with its iine the primary to be attached to the battery-poles permanently We will not make or break the circuit, and we can still produce currents, ”iine the priain h it Every tienerated in the secondary which will be opposite in direction to the current in the priain, an impulse in the secondary will be in the sa, as before, as the primary wire is quiet, there will be no secondary current at all

There is still a third effect If the current in the primary be _increased or diminished_ we shall have impulses in the secondary

This is a supposed case, to render the facts, the laws of induction, clear to the understanding The experiht actually be performed if an instrument sufficiently delicate were attached to the terminals of the secondary tofacts are deduced froard to all induced currents They are the priins, which approaches, or which increases in strength in the primary, induces, with these movements or conditions, a momentary current in the _opposite direction_ in the secondary

A current which stops, which retires, or which decreases in strength in the primary, induces a momentary current _in the same direction_ with the current in the primary

To make the results of induction effective in practice, we th of wire, and to this end, as in the case of the electro-net, ill adopt the spool form We will suppose tires, insulated so as to keep theether side by side, and wound upon a core in several layers There will then be tires in the coil, and the opposite ends of one of these wires ill attach to the poles of a battery, and send a current through the coil

This would then be the primary, and the other would be the secondary, as described above But, since the power and efficiency of an induced current depends upon the length of the secondary wire that is exposed to the influence of the current carried by the prih to slip inside of the other This smaller, inner coil is made with coarser wire than the outer, and the latter has an ih the smaller, inside coil, and each time that it is stopped, or started, there will be an ih the outer--the secondary coil Leave the current uninterrupted, and move the outer coil, or the inner one, back and forth, and the sa impulses will be observed in the coil that has no connection with any source of electricity

What I have just described as an illustration of the laws governing the production of induced currents, is, in fact, what is known as the _Induction Coil_ In the old tio it was extensively used as an illustrator of the power of the electric current Sometimes the outer coil contained fifty miles of wire, and the spark, a close i, would pass between the terminals of the secondary coil held apart for a distance of several feet, and would pierce sheets of plate glass three inches thick Before the days of practical electric lighting the induction-coil was used for the sis, and is still so used to a limited extent Its description is introduced here as an illustration of the laws of induction which the reader will find applied hereafter in newer and more effective ways The commonest instance now of the use of the induction-coil is in the very frequent small machine known as athe current (the circuit) as described above This, in the medical battery, is auto sound The mechanism is easily understood upon examination

At some risk of tediousness with those who have already made an examination of elementary electricity, I have now endeavored to convey to the reader a clear idea of (1), what electricity is, so far as known

(2) Of how the current is conducted, and its influence in the field surrounding the conductor (3) The nature of the induced current, and the manner in which it is produced The sum of the information so far net, and how to produce an induced current Such infore of these two ite of the details, will be found, collectively or separately, to underlie an understanding of all the machines and appliances of modern electricity, and in all probability, of all those that are yet to co (to which presently we shall come), there is still another principle involved, and this requires soiven here as elsewhere) of the current theory as to what electricity is [Footnote: There are several ”schools” a scientists, those who pursue pure science, irrespective of practical applications, and who are rather disposed to narrow the ter themselves upon the question of what electricity is The ”Substantialists” believe that it is a kind of matter Others deny that, and insist that it is a ”fory,” on which point there can be no serious question Still others reject both these views Tesla has said that ”nothing stands in the way of our calling electricity 'ether associated with e says it is ”a form, or rather a mode of manifestation, of the ether” The question is still in dispute whether we have only one electricity or two opposite electricities The great field of che the solution of the question within its possibilities The practical electrician acts upon facts which he knows are true without knowing their cause; empirically; and so far adheres to the molecular hypothesis The demonstrations and experiments of Tesla so far produce only new theories, or de absolute Nevertheless, under his investigations, the possibilities of the near future are widely extended By h frequency, he has succeeded in passing by induction, through the glass of 1 lay sufficient to keep a filament in a state of incandescence _without the use of any connecting wires_

He has even lighted a roo applianceelectrically connected with anything He has produced the required condition by creating in the roo very rapidly He suspends two sheets of metal, each connected with one of the terminals of the coil If an exhausted tube is carried anywhere between these sheets, or placed anywhere, it re of the unquestionable possibilities are shown in the following quotation from _Nature_, as expressed in a lecture by Prof Crookes upon the implied results of Tesla's experiments

The extent to which this method of illumination may be practically available, experiht into the possibilities of static electricity has been extended, and the ordinary electric arded as acurrents have, at the best, a rather doubtful reputation

But it follows from Tesla's researches that, is the rapidity of the alternation increases, they becoerous but less so It further appears that a true flame can now be produced without cheht and heat without the consumption of material and without any chemical process To this end we require i excessively frequent alternations and enor the ether? If so, we may view the prospective exhaustion of our coal-fields with indifference; we shall at once solve the ss

Electricity seems destined to annex the whole field, not merely of optics, but probably also of therh a wall, nor, as we know only too well, through a dense fog But electrical rays of a foot or tave-length, of which we have spoken, will easily pierce such mediu field for research, scarcely yet attacked by pioneers, awaits exploration I allude to the mutual action of electricity and life No sound man of science indorses the assertion that ”electricity is life” nor can we even venture to speak of life as one of the varieties or y Nevertheless, electricity has an important influence upon vital pheno--anietable We have electric fishes--one of them the prototype of the torpedo ofwhich used to be ardens and roads about Hoinsey Rise; there is also an electric centipede In the study of such facts and such relations the scientific electrician has before him an almost infinite field of inquiry

The slower vibrations to which I have referred reveal the bewildering possibility of telegraphy without wires, posts, cables, or any of our present costly appliances It is vain to atteress, as Dean Swift observed, may be ”too fast for endurance”] As to this, all we may be said to know, as has been rey_, and its manifestations are in the form of _motion_ of the minute and invisible atoms of which it is co the length of a conductor There must, of course, be an end to this process in theory, because all the molecules once movedain Therefore it is necessary to add that when the motion of the lastit to utility, the last particles, atoain receiveparticles, and this trans a conductor is continuous--continually absorbed and repeated This is _dyna in kind, in essence, from any other, but only in application

If the conductor is entirely insulated, so that no uous bodies, all its particles beco as the conductor is attached to a source of electricity In such a case an additional charge is required only when soe is taken away, escapes This is _Static_ electricity; the sa in application

The molecular theory is, unquestionably, tenable under present conditions It is that to which science has attained in its inquiries to the present date The electric light is scarcely explainable upon any other hypothesis The reuan with static electricity, so called, because its sources were more readily and easily discovered in the course of scientific accidents, as in the original discovery of the property of rubbed aations that were suggested by that antique, accidental discovery What we know as the dynaations of Faraday; induction was its mother It is the practically iation required the invention of machinery to perform its necessary operations