Yet the mystery is not yet entirely explained. In the study of electricity we are accustomed to accept demonstrated facts as we find them. When it is askedhowa battery acts, what produces the mysterious current, the only answer that can now be given is that it isby the conversion of the energy of chemical affinity into the energy of electrical vibrations. Many mixtures produce heat. The explanation can be no clearer than that for electricity. Electricity and heat are bothforms of energy, and, indeed, are so similar that one is almost synonymous with the other. The enquiry into the original sources of energy, latent but present always, will, when finally answered, give us an insight into mysteries that we can only now infer are reserved for that hereafter, here or elsewhere, which it is part of our nature to believe in and hope for. The theory of electrical vibrations is explained elsewhere as the only tenable one by which to account for electrical action. One may also ask how fire burns, or, rather, why a burning produces what we call "heat," and the actual question cannot be answered. The action of fire in consuming fuel, and the action of chemicals in consuming metals, are similar actions. They each result in the production of a new form of energy, and of energy in the form of vibrations. In the action of fire the vibrations are irregular and spasmodic; in electricity they are controlled by a certain rhythm or regularity. Between heat and electricity there is apparently only this difference, and they are so similar, and one is so readily converted into the other, that it is a current scientific theory that one is only a modified form of the other. Many acute minds have reflected upon the problem of how to convert the latent energy of coal into the energy of electricity without the interposition of the steam engine and machinery. There apparently exist reasons why the problem will never be solved. There is no intelligence equal to answering the question as to precisely where the heat came from, or how it came, that instantly results upon the striking of a common match. It wasevolvedthrough friction. The means were necessary. Friction, or its precise equivalent in energy, must occur. The result is as strange, and in the same manner strange, as any of the phenomena of electricity. Precisely here, in the beginning of the study of these phenomena, the student should be warned that an attitude of wonder or of awe is not one of enquiry. The demonstrations of electricity are startling chiefly for three reasons: newness, silence, and inconceivable rapidity of action. Let one hold a wire in one's hand six or eight inches from the end, and then insert that end into the flame of a gas-jet. It is as old as human experience that that part of the wire which is not in the flame finally grows hot, and burns one's fingers. A change has taken place in the molecules of the wire that is not visible, is noiseless, and that hastraveled along the wire. It excites neither wonder nor remark. No one asks the reason why. Yet it cannot be explained except by some theory more or less tenable, and the phenomenon, in kind though not in degree, is as unaccountable as anything in the magic of electricity. In a true sense there is, nothing supernatural, or even wonderful, in all the vast universe of law. If we would learn the facts in regard to anything, it must be after we have passed the stage of wonder or of reverence in respect to it. That which was the "Voice of God"--as truly, in a sense, it was and is--until Franklin's day, has since been a concussion of the air, an echo among the clouds, the passage of an electric discharge. It is the first lesson for all those who would understand.
The time had now come when that which had seemed a lawless wonder should have its laws investigated, formulated and explained. A man named Coulomb, a Frenchman, is the author of a system of measurements of the electric current, and he it was who discovered that the action of electricity varies, not with the distance, but, like gravity,in the inverse ratio of the square of the distance. Coulomb was the maker of the first instrument for measuring a current, which was known as thetorsion balance. The results of his practical investigations made easier the practical application of electrical power as we now use it, though he foresaw nothing of that application; and the engineer of to-day applies his laws, and those of his fellow scientists, as those which do not fail. Volta was one of these, and he also furnished, as will hereafter be seen, a name for one of the units of electrical measurement.
Both Galvani and Volta passed into shadow, when, in 1820, Professor H. C. Oersted, of Copenhagen, discovered the law upon which were afterwards slowly built the electrical appliances of modern life. It was the great principle of INDUCTION. The student of electricity may begin here if he desires to study only results, and is not interested in effects, causes, and the pains and toils which led to those results. The term may seem obscure, and is, doubtless, as a name, the result of a sudden idea; but upon induction and its laws the simplest as well as the most complicated of our modern electrical appliances depend for a reason for action. Its discovery set Ampère to work. They had all imagined previously that there was some connection between electricity and magnetism, and it was this idea that instigated the investigations of Ampere. It was imagined that the phenomena of electricity were to be explained by magnetism. This was not untrue, but it was only a part of the truth. Ampere proved thatmagnetism could also readily be produced by a current of electricity. From this idea, practically carried out, grew the ELECTRO MAGNET, and to Ampère we are indebted for the actual discovery of the elementary principles of what we now call electrodynamics, or dynamic electricity, [19] in which are included the Dynamo, and its twin and indispensable, the Motor. Ampère is also the author of themolecular theory, by which alone, with our present knowledge, can the action of electricity be explained in connection with the iron core which is made a magnet by the current, and left again a mere piece of iron when the current is interrupted. Ten years later Faraday explained and applied the laws of Induction, basing them upon the demonstrations of Ampère. The use of a core of soft iron, magnetized by the passage of a current through a helix of wire wrapping it as the thread does a spool, is the indispensable feature, in some form meaning the same thing, with the same results, in all machines that are given movement to by an electric current. This is the electro-magnet. It is made a magnet not by actual contact, or by being made the conductor of a current, but by being placed in the "electrical field" and temporarily magnetized by induction.
19.In all science there is a continual going back to the past for a means of expression for things whose application is most modern.Dynamic; DYNAMO, is the Greek word for power; to be able. Once established, these names are seldom abandoned. There is no more reason for calling our electrical power-producing machine a "Dynamo" than there would be in so designating a steam engine or a water-wheel. But, a term of general significance if used at all, it has come to be the special designation of that one machine. It is brief, easily said, and to the point, but is in no way necessarily connected withelectricalpower distinctively.
Faraday began his brilliant series of experiments in 1831. To express briefly the laws of action under which he worked, he wrote the celebrated statement of the Law of Magnetic Force. He proved that the current developed by induction is the same in all its qualities with other currents, and, indeed, demonstrated Franklin's theory that all electricity is the same; that, as tokind, there is but one. All electrical action is now viewed from the Faradic position.
The story of electricity, as men studied it in the primary school of the science, ends where Faraday began. Under the immutable laws he discovered and formulated we now enter the field of result, of action, of commercial interest and value. We might better say the field of usefulness, since commercial value is but another expression for usefulness. A revolution has been wrought in all the ways and thoughts of men since a date which a man less than sixty years old can recall. The laws under which the miracle has been wrought existed from all eternity. They were discovered but yesterday. Progress, the destiny of man, has kept pace in other fields. We live our time in our predestined day, learning and knowing, like grown-up children, what we may. In a future whose distance we may not even guess, the children of men shall reap the full fruition of the prophesy that has grown old in waiting, and "shall be as gods, knowing good from evil."
Electricity, in all its visible exhibitions, has certain unvarying qualities. Some of these have been mentioned in the preceding chapter. Others will appear in what is now to follow. These qualities or habits, invariable and unchangeable, are, briefly:
(1) It has the unique power of drawing, "attracting" other objects at a distance.
(2) For all human uses it is instantaneous in action, through a conductor, at any distance. A current might be sent around the world while the clock ticked twice.
(3) It has the power of decomposing chemicals (Electrolysis), and it should be remembered that even water is a chemical, and that substances composed of one pure organic material are very rare.
(4) It is readily convertible into heat in a wire or other conductor.
These four qualities render its modern uses possible, and should be remembered in connection with what is presently to be explained.
These uses are, in application, the most startling in the entire history of civilization. They have come about, and their applications have been made effective, within twenty years, and largely within ten. This subtlest and most elusive essence in nature, not even now entirely understood, is a part of common life. Some years ago we began to spell our thoughts to our fellow-men across land and sea with dots and dashes. Within the memory of the present high school boy we began to talk with each other across the miles. Now there is no reason why we shall not begin to write to each other letters of which the originals shall never leave our hands, yet which shall stand written in a distant place in our own characters, indisputably signed by us with our own names. We apparently produce out of nothing but the whirling of a huge bobbin of wire any power we may wish, and send it over a thin wire to where we wish to use it, though every adult can remember when the difficulty of distance, in the propelling of machinery, was thought to have been solved to the satisfaction of every reasonable man by the making of wire cables that would transmit power between grooved wheels a distance of some hundreds of feet. We turn night into day with the glow of lamps that burn without flame, and almost without heat, whose mysterious glow is fed from some distant place, that hang in clusters, banners, letters, in city streets, and that glow like new stars along the treeless prairie horizon where thirty years ago even the beginnings of civilization were unknown. Yet the mysterious agent has not changed. It is as it was when creation began to shape itself out of chaos and the abyss. Men have changed in their ability to reason, to deduce, to discover, and to construct. To know has become a part of the sum of life; to understand or to abandon is the rule. When the ages of tradition, of assertion without the necessity for proof, of content with all that was and was right or true because it was a standard fixed, went by, the age not necessarily of steam, or of steel, or of electricity, but the age of thought, came in. Some of the results of this thought, in one of the most prominent of its departments, I shall attempt to describe.
A wire is the usual concomitant in all electrical phenomena. It is almost the universally used conductor of the current. In most cases it is of copper, as pure as it can be made in the ordinary course of manufacture. There are other metals that conduct an electrical current even better than copper does, but they happen to be expensive ones, such as silver. The usual telegraph-line is efficient with only iron wire.
We habitually use the words "conductor" and "conduct" in reference to the electric current. A definition of that common term may be useful. It is a relative one.A conductor is any substance whose atoms, or molecules, have the power of conveying to each other quickly their electricities. Before the common use of electricity we were accustomed to commonly speak of conductors of heat; good, or poor. The same meaning is intended in speaking of conductors of electricity.Non-conductors are those whose molecules only acquire this power under great pressure. Electricity always takes theeasiestroad, not necessarily the shortest. This is the path that electricians call that of "least resistance." There are no absolutely perfect conductors, and there are no substances that may be called absolutely non-conductors. A non-conductor is simply a reluctant, an excessively slow, conductor. In all electrical operations we look first for these two essentials: a good conductor and a good non-conductor. We want the latter as supports and attachments for the first. If we undertake to convey water in a pipe we do not wish the pipe to leak. In conveying electricity upon a wire we have a little leak wherever we allow any other conductor to come too near, or to touch, the wire carrying the current. These little electrical leaks constantly exist. All nature is in a conspiracy to take it wherever it can find it, and from everything which at the moment has more than some other has, or more than its share with reference to the air and the world, of the mysterious essence that is in varying quantities everywhere. Glass is the usual non-conductor in daily use. A glance at the telegraph poles will explain all that has just been said. Water in large quantity or widely diffused is a fair conductor. Therefore, the glass insulators on the telegraph-poles are cup-shaped usually on the under side where the pin that holds them is inserted, so that the rain may not actually wet this pin, and thus make a water-connection between the wire, glass, pin, pole and ground.
We are accustomed to things that are subject to the law of gravity. Water will run through a pipe that slants downward. It will pass through a pipe that slants upward only by being pushed. But electricity, in its far journeys over wires, is not subject to gravity. It goes indifferently in any direction, asking only a conductor to carry it. There is also a trait calledinertia; that property of all matter by which it tends when at rest to remain so, and when in motion to continue in motion, which we meet at every step we take in the material world. Electricity is again an exception. It knows neither gravity, nor inertia, nor material volume, nor space. It cannot be contained or weighed. Nothing holds it in any ordinary sense. It is difficult to express in words the peculiar qualities that caused the early experimenters to believe it had a soul. It is never idle, and in its ceaseless journeyings it makes choice of its path by a conclusion that is unerring and instantaneous.
We find that it is the constant endeavor of electricity toequalize its quantities and its two qualities, in all substances that are near it that are capable of containing it. To this end, seemingly by definite intention, it is found on the outsides of things containing it. It gathers on the surfaces of all conductors. If there are knobs or points it will be found in them, ready to leap off. When any electrified body is approached by a conductor, the fluid will gather on the side where the approach is made. If in any conductor the current is weak, very little of it, if any, will go off into the conductor before actual contact is made. If it is strong, it will often leap across the space with a spark. One body may be charged with positive, and another with negative, electricity. There is then a disposition to equalize that cannot be easily repressed. The positive and the negative will assume their dual functions, their existence together, in spite of obstacles. So as to quantity. That which has most cannot be restrained from imparting to that which has less. The demonstration of these facts belongs to the field of experimental, or laboratory, electricity. The most common of the visible experiments is on a vast scale. It is the thunder-storm. Mother Earth is the great depository of the fluid. The heavy clouds, as they gather, are likewise full. Across the space that lies between the exchange takes place--the lightning-flash.
In the preceding chapter I have hastily alluded to the phenomenon known as the key to electricity as a utilitarian science; a means of material usefulness. These uses are all made possible under the laws of what we term INDUCTION. To comprehend this remarkable feature of electric action, it must first be understood that all electrical phenomena occur in what has been termed an "Electrical Field" This field may be illustrated simply. A wire through which a current is passingis always surrounded by a region of attractive force. It is scientifically imagined to exist in the form of rings around the wire. In this field lie what are termed "lines of force." The law as stated is that the lines in which the magnetism produced by electricity actsare always at right angles with the direction in which the current is passing. Let us put this in ordinary phrase, and say that in a wire through which a current is passing there is a magnetic attraction, and that the "pull" is alwaysstraight toward the wire. This magnetism in a wire, when it is doubled up and multiplied sufficiently, has strong powers of attraction. This multiplying is accomplished by winding the wire into a compact coil and passing a current through it. If one should wind insulated wire around a core, or cylinder, and should then pull out the cylinder and attach the two ends of the wire to the opposite poles of a battery, when the current passed through the coil the hollow interior of it would be a strong magnetic field. The air inside might be said to be a magnet, though if there were no air there, and the coil were under the exhausted receiver of an air-pump, the effect would be the same, and thevacuumwould be magnetized. A piece of iron inserted where the core was, would instantly become a magnet, and when the insulated wire is wound around a soft iron core, and the core is left in place, we have at once what is known as anElectro-Magnet.
The wire windings of an electro-magnet are always insulated; wound with a non-conductor, like silk or cotton; so that the coils may not touch each other in the winding and thus permit the current to run off through contact by the easiest way, and cut across and leave most of the coil without a current. For it may as well be stated now that no matter how good a conductor a wire may be, two qualities of it cause what is called "resistance"--the current does not pass so easily. These two qualities arethinnessandlength. The current will not traverse all the length of a long coil if it can pass straight through the same mass, and it is made to go the long wayby keeping the wires from touching each other--preventing "contact," and lessening the opportunity to jump off which electricity is always looking for.
When this coil is wound in layers, like the thread upon a spool, it increases the intensity of the magnetism in the core by as many times as there are coils, up to a certain point. If the core is merely soft iron, and not steel, it becomes magnetized instantly, as stated, and will draw another piece of iron to it with a snap, and hold it there as long as there is a current passing through the coil. But as instantly, when the current is stopped, this soft iron core ceases to be a magnet, and becomes as it was before--an inert and ordinary piece of iron. What has just been described is always, in some form, one of the indispensable parts of the electromagnetic machines used in industrial electricity, and in all of them except the appliances of electric lighting, and even in that case it is indispensable in producing the current which consumes the points of the carbon, or heats the filament to a white glow. The current may traverse the wire for a hundred miles to reach this little coil. But, instantly, at a touch a hundred miles away that forms a contact, there is a continuous "circuit;" the core becomes a magnet, and the piece of iron near it is drawn suddenly to it. Remove the distant finger from the button, the contact is broken, and the piece of iron immediately falls away again. It is the wonder ofthe production of instant movement at any distance, without any movement of any connecting part. It is a mysterious and incredible transmission of force not included among human possibilities forty years ago. It is now common, old, familiar. Conceive of its possibilities, of its annihilation of time and space, of its distant control, and of that which it is made to mean and represent in the spelled-out words of language, and it still remains one of the wonders of the world: the Electric Telegraph.
MAGNETS AND MAGNETISM.--Having described a magnet that is made and unmade at will, it may be appropriate to describe magnets generally. The ordinary, permanent magnet, natural or artificial, has little place in the arts. It cannot be controlled. In common phrase, it cannot be made to "let go" at will. The greatest value of magnetism, as connected with electricity, consists in the fact of the intimate relationship of the two. A magnet may be made at will with the electric current, as described above. A little later we shall see how the process may be reversed, and the magnet be made to produce the most powerful current known, and yet owe its magnetism to the same current.
The wordMagnetcomes from the country ofMagnesia, where "loadstone" (magnetic iron ore) seems first to have been found. The artificial magnet, 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 temper, which has been magnetized, usually by having had a current passed through or around it, and sometimes by contact with another magnet. For the singular property of a magnet is that it may continually impart its quality, yet never lose any of its own. Steel alone, of all the metals, has the decided quality of retaining its property of being a magnet. A "bar" magnet is a straight piece of steel magnetized. A "horseshoe" magnet is a bar magnet bent into the form of the letter "U."
Every magnet has two "poles"--the positive, or North pole, and the negative, or South pole. If any magnet, of any size, and having as one piece two poles only, be cut into two, or a hundred pieces, each separate piece will be like the original magnet 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 mysterious code. All bar magnets, when suspended by their centers, turn their ends to the North and South, a familiar example of this being the ordinary compass. But in magnetism,like repels like. The world is a huge magnet. The pole of the magnet 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, becomes a powerful and effective magnet 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 permanently. Iron and steel are the magnetic metals, but there is a considerable list of metals not magnetic that are better than they asconductorsof 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 impossible. All the phenomena of combined magnetism and electricity, all that goes 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-magnet, 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 becomes a magnet, not necessarily by any actual contact with any other magnet, or by touching or rubbing, but by being placed in an electric field. It acquired its magnetism by induction; bydrawing in(since that is the meaning of the term) the electricity that was around it. But induction has a still wider field, and other characteristics than this alone. Some distinct idea of these may be obtained by supposing a simple case, in which I shall ask the reader to follow me.
DIAGRAM THEORY OF INDUCTION
Let us imagine 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 may pass through 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 anopposite directionfrom the first wire's current. But this current in the second wire does not continue. It is a momentary impulse, existing only at the moment of the first passing of the current through 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 wire will show another impulse, this time in thesame directionwith 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 thePrimary. The second unattached wire, with its impulses, is called theSecondary.
Let us now imagine the primary to be attached to the battery-poles permanently. We will not make or break the circuit, and we can still produce currents, "impulses," in the secondary. Let us imagine the primary to be brought nearer to the secondary, and again moved away from it, the current passing all the time through it. Every time it is moved nearer, an impulse will be generated in the secondary which will be opposite in direction to the current in the primary. Every time it is moved away again, an impulse in the secondary will be in the same direction as the primary current. So long, 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 beincreased or diminishedwe shall have impulses in the secondary.
This is a supposed case, to render the facts, the laws of induction, clear to the understanding. The experiment might actually be performed if an instrument sufficiently delicate were attached to the terminals of the secondary to make the impulses visible. The following facts are deduced from it in regard to all induced currents. They are the primary laws of induction:--
A current which begins, which approaches, or which increases in strength in the primary, induces, with these movements or conditions, a momentary current in theopposite directionin the secondary.
A current which stops, which retires, or which decreases in strength in the primary, induces a momentary currentin the same directionwith the current in the primary.
To make the results of induction effective in practice, we must have great length of wire, and to this end, as in the case of the electro-magnet, we will adopt the spool form. We will suppose two wires, insulated so as to keep them from actually touching, held together side by side, and wound upon a core in several layers. There will then be two wires in the coil, and the opposite ends of one of these wires we will 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 primary, we fix two separate coils, one small enough to slip inside of the other. This smaller, inner coil is made with coarser wire than the outer, and the latter has an immense length of finer wire. The current is passed through the smaller, inside coil, and each time that it is stopped, or started, there will be an impulse, and a very strong one, through the outer--the secondary coil. Leave the current uninterrupted, and move the outer coil, or the inner one, back and forth, and the same series of strong 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 theInduction Coil. In the old times of a quarter of a century ago 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 imitation of a flash of lightning, 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 simultaneous lighting of the gas-jets in public buildings, 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 a medical battery. There must be a means of making and breaking the current (the circuit) as described above. This, in the medical battery, is automatic, and it is that which produces the familiar buzzing 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 may be stated in other words to be how to make an electromagnet, and how to produce an induced current. Such information has an end in view. A knowledge of these two items, an understanding 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 come.
But in the prominent field of electric lighting (to which presently we shall come), there is still another principle involved, and this requires some explanation (as well given here as elsewhere) of the current theory as to what electricity is. [20] As to this, all we may be said to know, as has been remarked, is that it is one of theforms of energy, and its manifestations are in the form ofmotionof the minute and invisible atoms of which it is composed. This movement is instantaneously communicated along the length of a conductor. There must, of course, be an end to this process in theory, because all the molecules once moved must return to rest, or to a former condition, before being moved again. Therefore it is necessary to add that when the motion of the last molecule has been absorbed by some apparatus for applying it to utility, the last particles, atoms, molecules, are restored to rest, and may again receive motion from infringing particles, and this transmission of energy along a conductor is continuous--continually absorbed and repeated. This isdynamicelectricity; not differing in kind, in essence, from any other, but only in application.
20.There are several "schools" among scientists, those who pursue pure science, irrespective of practical applications, and who are rather disposed to narrow the term to include that field alone, that are divided among 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 "form of Energy," 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 matter, or bound ether.'" Professor Lodge 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 chemistry enters into the discussion as perhaps having 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 demonstrate the fallacies of the old, but give us nothing absolute. Nevertheless, under his investigations, the possibilities of the near future are widely extended. By means of currents alternating with very high frequency, he has succeeded in passing by induction, through the glass of 1 lamp, energy sufficient to keep a filament in a state of incandescencewithout the use of any connecting wires. He has even lighted a room by producing in it such a condition that an illuminating appliance may be placed anywhere and lighted without being electrically connected with anything. He has produced the required condition by creating in the room a powerful electrostatic field alternating 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 remains always luminous.
Something of the unquestionable possibilities are shown in the following quotation fromNature, 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, experiments alone can decide. In any case, our insight into the possibilities of static electricity has been extended, and the ordinary electric machine will cease to be regarded as a mere toy.
Alternating currents have, at the best, a rather doubtful reputation. But it follows from Tesla's researches that, is the rapidity of the alternation increases, they become not more dangerous but less so. It further appears that a true flame can now be produced without chemical aid--a flame which yields light and heat without the consumption of material and without any chemical process. To this end we require improved methods for producing excessively frequent alternations and enormous potentials. Shall we be able to obtain these by tapping the ether? If so, we may view the prospective exhaustion of our coal-fields with indifference; we shall at once solve the smoke question, and thus dissolve all possible coal rings.
Electricity seems destined to annex the whole field, not merely of optics, but probably also of thermotics.
Rays of light will not pass through a wall, nor, as we know only too well, through a dense fog. But electrical rays of a foot or two wave-length, of which we have spoken, will easily pierce such mediums, which for them will be transparent.
Another tempting 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 manifestations of energy. Nevertheless, electricity has an important influence upon vital phenomena, and is in turn set in action by the living being--animal or vegetable. We have electric fishes--one of them the prototype of the torpedo of modern warfare. There is the electric slug which used to be met with in gardens 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 attempt to picture the marvels of the future. Progress, as Dean Swift observed, may be "too fast for endurance."
If the conductor is entirely insulated, so that no molecular movements can be communicated by it to contiguous bodies, all its particles become energized, and remain so as long as the conductor is attached to a source of electricity. In such a case an additional charge is required only when some of the original charge is taken away, escapes. This isStaticelectricity; the same as the other, but in theory differing 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 remaining conclusions may be left in abeyance, and without argument.
Science began 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 amber, etc., and the long course of investigations that were suggested by that antique, accidental discovery. What we know as the dynamic branch of the subject was created by the investigations of Faraday; induction was its mother. It is the practically important branch, but its investigation required the invention of machinery to perform its necessary operations. Between the two branches the sole difference--a difference that may be said not actually to exist--is inquantity and pressure.
To the department of static electricity all those industrial appliances first known belong, as the telegraph, electro-plating, etc. I shall first consider this class of appliances and machines. The most important of the class is
THE ELECTRIC TELEGRAPH.--The word is Greek, meaning, literally, "to write from a distance." But long since, and before Morse's invention, it had come to mean the giving of any information, by any means, from afar. The existence of telegraphs, not electric, is as old as the need of them. The idea of quickness, speedy delivery, is involved. If time is not an object, men may go or send. The means used in telegraphing, in ancient and modern times, have been sound and sight. Anything that can be expressed so as to be read at a distance, and that conveys a meaning, is a telegram. [21] Our plains Indians used columns of smoke, or fires, and are the actual inventors of theheliograph, now so called, though formerly meaning the making of a picture by the aid of the sun--photography. The vessels of a squadron at sea have long used telegraphic signals. Some of the celebrated sentences of our history have been written by visual signals, such as "Hold the fort, for I am coming," "Don't give up the ship," etc. Order of showing, positions, and colors are arbitrarily made to mean certain words. The sinking of the "Victoria" in 1893, was brought about by the orders conveyed by marine signals. Bells and guns signal by sound. So does the modern electric telegraph, contrary to original design. It is all telegraphy, but it all required an agreed and very limited code, and comparative nearness. None of the means in ancient use were available for the multifarious uses of modern commerce.
21.This word is of American coinage, and first appeared in theAlbany Evening Journal, in 1852. It avoids the use of two words, as "Telegraphic Message," or "Telegraphic Dispatch," and the ungrammatical use of "Telegraph," for a message by telegraph. The new word was at once adopted.
As soon as it was known that electricity could be sent long distances over wires, human genius began to contrive a way of using it as a means of conveying definite intelligence. The first idea of the kind was attempted to be put into effect in 1774. This was, however, before the discovery of the electro-magnet (about 1800), or even the Galvanic battery, and it was seriously proposed to have as many wires as there were letters; each wire to have a frictional battery for generating electricity at one end of the circuit, and a pith-ball electroscope at the other. The modern reader may smile at the idea of the hurried sender of a message taking a piece of cat-skin, or his silk handkerchief, and rubbing up the successive letter-balls of glass or sulphur until he had spelled out his telegram. Later a man named Dyer, of New York, invented a system of sending messages by a single wire, and of causing a record to be made at the receiving office by means of a point passing over litmus paper, which the current was to mark by chemical action, the paper passing over a roller or drum during the operation. The battery for this arrangement was also frictional. They knew of no other. Then came the deflected-needle telegraph, first suggested by Ampère, and a few such lines were constructed, and to some extent operated. In one of the original telegraph lines the wires were bound in hemp and laid in pipes on the surface of the ground. The expedient of poles and atmospheric insulation was not thought of until it was adopted as a last resort during the construction of Morse's first line between Washington and Baltimore.
In the year 1832, an American named Samuel F. B. Morse was making a voyage home from Havre to New York in the sailing packetSully. He was an educated man, a graduate of Yale, and an artist, being the holder of a gold medal awarded him for his first work in sculpture, and no want of success drove him to other fields. But during this tedious voyage of the old times in a sailing vessel he seems to have conceived the idea which thenceforth occupied his life. It was the beginning of the present Electric Telegraph. During this same voyage he embodied his notions in some drawings, and they were the beginnings of vicissitudes among the most long-continued and trying for which life affords any opportunity. He abandoned his studies. He paid attention to no other interest. He passed years in silent and lonesome endeavors that seemed to all others useless. He subjected himself to the reproaches of all his friends, lost the confidence of business men, gained the reputation of being a monomaniac, and was finally given over to the following of devices deemed the most useless and unpromising that up to that time had occupied the mind of any man.
The rank and file of humanity had no definite idea of the plan, or of the results that would follow if it were successful. In reality no one cared. It was Morse's enterprise exclusively--a crank's fad alone. There has been no period in the history of society when the public, as a body, was interested in any great change in the systems to which it was accustomed. There is always enmity against an improver. In reality, the question of how much money Morse should make by inventing the electric telegraph was the question of least importance. Yet it was regarded as the only one. He is dead. His profits have gone into the mass, his honors have become international. The patents have long expired. The public, the entire world, are long since the beneficiaries, and the benefits continue to be inconceivably vast. Nothing in all history exceeds in moral importance the invention of the telegraph except the invention of printing with movable types.
AN ELECTRO-MAGNET OF MORSE'S TIME
After eight years of waiting, and the repeated instruction of the entire Congress of the United States in the art of telegraphy, that body was finally induced to make an appropriation of thirty thousand dollars to be expended in the construction of an experimental line between Washington and Baltimore. And now begins the actual strangeness of the story of the Telegraph. After many years of toil, Morse still had learned nothing of the efficient construction of an electro-magnet. The magnet which he attempted to use unchanged was after the pattern of the first one ever made--a bent U-shaped bar, around which were a few turns of wire not insulated. The bar was varnished for insulation, and the turns of wire were so few that they did not touch each other. The apparatus would not work at a distance of more than a few feet, and not invariably then. Professor Leonard D. Gale suggested the cause of the difficulty as being in the sparseness of the coils of wire on the magnet and the use of a single-cell battery. He furnished an electro-magnet and battery out of his own belongings, with which the efficiency of the contrivance was greatly increased. The only insulated wire then known was bonnet-wire, used by milliners for shaping the immense flaring bonnets worn by our grandmothers, and when it finally came to constructing the instruments of the first telegraphic system the entire stock of New York was exhausted. The immense stocks of electrical supplies now available for all purposes was then, and for many years afterwards, unknown. Previous to the investigations of Professor Henry, in 1830, only the theory of causing a core of soft iron to become a magnet was known, and the actual magnet, as we make it, had not been made. Morse, in his beginnings, had not money enough to employ a competent mechanic, and was himself possessed of but scant mechanical skill or knowledge of mechanical results. Persistency was the quality by which he succeeded.
DIAGRAM OF MORSE'S INSTRUMENT, 1830, WITH ITS WRITING
The battery used first by Morse, as stated, was a single cell. The one made later by his partner, Alfred Vail, the real author of all the workable features of the Morse telegraph, and of every feature which identifies it with the telegraph of the present, was a rectangular wooden box divided into eight compartments, and coated inside with beeswax so that it might resist the action of acids. The telegraphic instrument as made by Morse was a rectangular frame of wood, now in the cabinet of the Western Union Telegraph Company, at New York, which was intended to be clamped to the edge of a table when in use. He knew nothing of the splendid invention since known as the "Morse Alphabet," and the spelling of words in a telegram was not intended by him. His complicated system, as described in his caveat filed by him in 1837, consisted in a system of signs, by which numbers, and consequently words and sentences, were to be indicated. There was then a set of type arranged to regulate and communicate the signs, and rules in which to set this type. There was a means for regulating the movement forward of the rule containing the types. This was a crank to be turned by the hand. The marking or writing apparatus at the receiving instrument was a pendulum arranged to be swungacrossthe slip of paper, as it was unwound from the drum, making a zig-zag mark the points of which were to be counted, a certain number of points meaning a certain numeral, which numeral meant a word. A separate type was used to represent each numeral, having a corresponding number of projections or teeth. A telegraphic dictionary was necessary, and one was at great pains prepared by Morse. His process was, therefore, to translate the message to be sent into the numerals corresponding to the words used, to set the types corresponding to those numerals in the rule, and then to pass the rule through the appliance arranged for the purpose in connection with the electric current. The receiver must then translate the message by reference to the telegraphic dictionary, and write out the words for the person to whom the message was sent. This was all changed by Vail, who invented the "dot-and-dash" alphabet, and modified the mechanical action of the instrument necessary for its use. The arrangement of a steel embossing-point working upon a grooved roller--a radical difference--was a portion of this change. The invention of the axial magnet, also Vail's, was another. Morse had regarded a mechanical arrangement for transmitting signals as necessary. Vail, in the practice of the first line, grew accustomed to sending messages by dipping the end of the wire in the mercury cup,--the beginning of the present transmitting instrument, which is also his invention--and Morse's "port-rule," types, and other complicated arrangements, went into the scrap-heap.
MODERN TRANSMITTER
Yet there were some strange things still left. The receiving relay weighed 185 pounds. An equally efficient modern one need not weigh more than half a pound. Morse had intended to make arecordingtelegraph distinctively; it was to his mind its chiefest value. Almost in the beginning it ceased to be such, and the recording portion of the instrument has for many years been unknown in a telegraph office, being replaced by the "sounder." This was also the invention of Vail. The more expert of the operators of the first line discovered that it was possible to read the signalsby the soundmade by the armature lever. In vain did the managers prohibit it as unauthorized. The practice was still carried on wherever it could be without detection. Morse was uncompromising in his opposition to the innovation. The wonderful alphabet of the telegraph, the most valuable of the separate inventions that make up the system, was not his conception. The invention of this alphabetical code, based on the elements of time and space, has never met with the appreciation it has deserved. It has been found applicable everywhere. Flashes of light, the raising and lowering of a flag, the tapping of a finger, the long and short blasts of a steam whistle, spell out the words of the English language as readily as does the sounder in a telegraph-office. It may be interpreted by sight, touch, taste, hearing. With a wire, a battery and Vail's alphabet, telegraphy is entirely possible without any other appliances.
MODERN 'SOUNDER.'
A brief sketch of the difficulties attending the making of the first practical telegraph line will be interesting as showing how much and how little men knew of practical electricity in 1843. [22] To begin with, it was a "metallic circuit;" that is, two wires were to be used instead of one wire and a "ground connection." They knew nothing of this last. Vail discovered and used it before the line was finished. The two wires, insulated, were inclosed in a pipe, lead presumably, and the pipe was placed in the ground. Ezra Cornell, afterwards the founder of Cornell University, had been engaged in the manufacture and sale of a patent plow, and undertook to make a pipe-laying machine for this new telegraph line. After the work had been begun Vail tested and united the conductors as each section was laid. When ten miles were laid the insulation, which had been growing weaker, failed altogether. There was no current. Probably every schoolboy now knows what the trouble was. The earth had stolen the current and absorbed it. The modern boy would simply remark "Induction," and turn his attention to some efficient remedy. Then, there was consternation. Cornell dexterously managed to break the pipe-laying machine, so as to furnish a plausible excuse to the newspapers and such public as there may be said to have been before there was any telegraph line. Days were spent in consultation at the Relay House, and in finding the cause of the difficulty and the remedy. Of the congressional appropriation nearly all had been spent. The interested parties even quarreled, as mere men will under such circumstances, and the want of a little knowledge which is now elementary about electricity came near wrecking forever an enterprise whose vast importance could not be, and was not then, even approximately measured.
22.There was no possibility of their knowing more, notwithstanding that, viewed from the present, their inexperienced struggles seem almost pathetic. So, also, do the ideas of Galvani and the experiments and conclusions of all except Franklin, until we come to Faraday. It is one of the features of the time in which we live that, regardless of age, we are all scholars of a new school in which mere diligence and behavior are not rewarded, and in which it is somewhat imperative that we should keep up with our class in an understanding ofwhat are now the facts of daily life, wonders though they were in the days of our youth.
ALFRED VAIL
Finally, after some weeks delay, it was decided to introduce what has become the most familiar feature of the landscape of civilization, and string the wires on poles. There is little need to follow the enterprise further. Morse stayed with one instrument in the Capitol at Washington, and Vail carried another with him at the end of the line. Already the type-and-rule and all the symbols and dictionaries had been discarded, and the dot-and-dash alphabet was substituted. On April 23d, 1844, Vail substituted the earth for the metallic circuit as an experiment, and that great step both in knowledge and in practice was taken.
Within an incredibly brief space the Morse Electric Telegraph had spread all over the world. No man's triumph was ever more complete. He passed to those riches and honors that must have been to him almost as a fulfilled dream. In Europe his progresses were like those of a monarch. He was made a member of almost all of the learned societies of the world, and on his breast glittered the medals and orders that are the insignia of human greatness. A congress of representatives of ten of the governments of Europe met in Paris in 1858, and it was unanimously decided that the sum of four hundred thousand francs--about a hundred thousand dollars--should be presented to him. He died in New York in 1872.
PROF. HENRY'S ELECTROMAGNET AND ARMATURE
Yet not a single feature of the invention of Morse, as formulated in his caveat and described in his original patent, is to be found among the essentials of modern telegraphy. They had mostly been abandoned before the first line had been completed, and the arrangements of his associate, Vail, were substituted. Professor Joseph Henry had, in 1832, constructed an electromagnetic telegraph whose signals were made by sound, as all signals now are in the so-called Morse system. He hung a bar-magnet on a pivot in its center as a compass-needle is hung. He wound a U-shaped piece of soft iron with insulated wire, and made it an electro-magnet, and placed the north end of the magnetized bar between the two legs of this electro-magnet. When the latter was made a magnet by the current the end of the bar thus placed was attracted by one leg of the magnet and repelled by the other, and was thus caused to swing in a horizontal plane so that the opposite end of it struck a bell. Thus was an electric telegraph made as an experimental toy, and fulfilling all the conditions of such an one giving the signals by sound, as the modern telegraph does. It lacked one thing--the essential. [23]
23.The details of the construction of the modern telegraph line are not here stated. There are none that change, in principle, the outline above given.
The Vail telegraphic alphabet had not been thought of. Had such an idea been conceived previously a message could have been read as it is read now, and with the toy of Professor Henry which he abandoned without an idea of its utility or of the possibilities of any telegraph as we have long known them. Morse knew these possibilities. He was one of the innumerable eccentrics who have been right, one of the prophets who have been in the beginning without honor, not only in respect to their own country, but in respect to their times.
DIAGRAM OF TELEGRAPH SYSTEM