Chapter VI: Part 6

Among the metallic substances, the one best adapted by its low conductivity to such resistance and transformation of force, is platinum. The high degree of heat necessary to fuse this metal adds to its usefulness and availability for the purpose indicated. When an electrical current is forced along a platinum wire too small to transmit the entire volume, it becomes at once heated--first to a red, and then to a white glow--and is thus made to send forth a radiance like that of the sun. Of the non-metallic elements which offer similar resistance, the best is carbon. The infusibility of this substance renders it greatly superior to platinum for purposes of the electric light.

Near the beginning of the present century it was discovered by Sir Humphry Davy that carbon points may be rendered incandescent by means of a powerful electrical current. The discovery was fully developed in the year 1809, while the philosopher just referred to was experimenting with the great battery of the Royal Institution of London. He observed--rather by accident than by design or previous anticipation--that a strong volume of electricity passing between two bits of wood charcoal produces tremendous heat, and a light like that of the sun. It appears, however, that Davy at first regarded the phenomenon rather in the nature of an interesting display of force than as a suggestion of the possibility of turning night into day.

For nearly three-quarters of a century the discovery made by Sir Humphrey lay dormant among the great mass of scientific facts revealed in the laboratory. In the course of time, however, the nature of the new fact began to be apprehended. The electric lamp in many forms was proposed and tried. The scientists, Niardet, Wilde, Brush, Fuller, and many others of less note, busied themselves with the work of invention. Especially did Gramme and Siemens devote their scientific genius to the work of turning to good account the knowledge now fully possessed of the transformability of the electric current into light.

The experiments of the last named two distinguished inventors brought us to the dawn of the new era in artificial lighting. The Russian philosopher, Jablokhkoff, carried the work still further by the practical introduction of the carbon candle. Other scientists--Carre, Foucault, Serrin, Rapieff, and Werdermann--had, at an earlier or later day, thrown much additional information into the common stock of knowledge relative to the illuminating possibilities of electricity. Finally, the accumulated materials of science fell into the hands of that untutored but remarkably radical inventor, Thomas A. Edison, who gave himself with the utmost zeal to the work of removing the remaining difficulties in the problem.

Edison began his investigations in this line of invention in September of 1878, and in December of the following year gave to the public his first formal statement of results. After many experiments with platinum, he abandoned that material in favor of the carbon-arc _in vacuo_. The latter is, indeed, the essential feature of the Edison light. A small semicircle, or horseshoe, of some substance, such as a filament of bamboo reduced to the form of pure carbon, the two ends being attached to the poles of the generating-machine, or dynamo, as the engine is popularly called, is enclosed in a glass bulb, from which the air has been carefully drawn, and is rendered incandescent by the passage of an electric current. The other important features of Edison's discovery relate to the divisibility of the current, and its control and regulation in volume by the operator. These matters were fully mastered in the Edison invention, and the apparatus rendered as completely subject to management as are the other varieties of illuminating agencies.

It were vain to speculate upon the future of electric lighting. The question of artificial illumination has had much to do with the progress of the human race, particularly when aggregated into cities. Doubtless the old systems of lighting are destined in time to give place altogether to the splendors of the electric glow. The general effect of the change upon society must be as marked as it is salutary. Darkness, the enemy of good government and morality in great cities, will, in great measure, be dispelled by the beneficent agent, over which the genius of Davy, Gramme, Brush, Edison, and a host of other explorers in the new continents of science has so completely triumphed. The ease, happiness, comfort, and welfare of mankind must be vastly multiplied, and the future must be reminded, in the glow that dispels the night, of that splendid fact that the progress of civilization depends, in a large measure, upon a knowledge of Nature's laws, and the diffusion of that knowledge among the people.

THE TELEPHONE.

Perhaps no other great invention of man has been within so short a period so widely distributed as the telephone. The use of the instrument is already co-extensive with civilization. The cost at which the instruments are furnished is still so considerable that the poor of the world are not able to avail themselves of the invention; but in the so-called upper circles of society the use of the telephone is virtually universal. It has made its way from the city to the town, from the town to the village, from the village to the hamlet, and even to the country-side where the millions dwell.

The telephone came by a speedy revelation. It was born of that intense scientific activity which is the peculiarity of our age. The antecedent knowledge out of which it sprang had existed in various forms for a long time. The laws of acoustics were among the first to be investigated after a true physical science began to be taught. The phenomena of sound are so universal and experimentation in sound production so easy, that the governing laws were readily discovered.

Acoustics, we think, foreran somewhat the science of heat, as the science of heat preceded that of light. Electricity came last. The telephone is an instrument belonging not wholly, not chiefly, but only in part, to acoustics. It owes its existence to magnetic induction and electrical transmission as much as to the mere action of sound. One foot of the instrument, so to speak, is acoustics, and the other foot electricity. The telephone philosophically considered is an instrument for the conversion of a sound-wave into electrical motion, and its reconversion into sound at a distance. The sound is, as it were, committed to the electrical current and is thus sent to the end of the journey, and there discharged with its message. The possibility of this result lies first of all in the fact of electrical transmission by wire, and in the second place to the mounting of a sound-rider on the electrical saddle for an instantaneous journey with important despatches!

New results in scientific progress generally seem marvelous. The unfamiliar and unexpected thing is always a marvel; but scientifically considered, the telephone does not seem so surprising as at first view. The atmosphere is a conductor of sound. It is the natural agent of transmission, and so far as the natural man is concerned, it is his only agent for the transmission of oral utterance. If the unlearned man have his attention called to the surprising fact of hearing his fellow-man call out to him across a field or from far off on the prairie, he does not think it marvelous, but only natural. Yet how strange it is that one human being can speak to another through the intervening space!

It is strange that one should see another at a distance; but seeing and hearing at distances are natural functions of living creatures. The sunlight is for one sense and the sound-wave is for the other. The sound-wave travels on the atmosphere, and preserves its integrity. A given sound is produced, and the same sound is heard by some ear at a distance. All the people of the world are telephoning to one another; for oral speech leaping from the vocal organs of one human being to the ear of another is always telephonic. It is only when this phenomenon of speech at a distance is taken from the soft wings of the air, confined to a wire, and made to fly along the slender thread and deliver itself afar in a manner to which the world has hitherto been a stranger that the thing done and the apparatus by which it is done seem miraculous. Indeed it is a miracle; for _miraculum_ signifies wonderful.

The history of the invention of the telephone is easily apprehended. The scientific principles on which it depends may be understood without difficulty. There is, however, about the instrument and its action something that is well nigh unbelievable. It is essentially a thing contrary to universal experience, if not positively inconceivable, that the slight phenomenon of the human voice should be, so to speak, _picked up_ by a physical contrivance, carried a thousand miles through a thread of wire not a quarter of an inch in diameter, and delivered in its integrity to the sense of another waiting to receive it! At all events, the history of the telephone, belonging so distinctly to our own age, will stand as a reminder to after times of the great stride which the human race made in inventive skill and scientific progress in the last quarter of the nineteenth century.

The telephone, like many similar instruments, was the work of several ingenious minds directed at nearly the same time to the same problem. The solution, however, must be accredited first of all to Elisha P. Gray, of Chicago, and Alexander Graham Bell, of the Massachusetts Institute of Technology. It should be mentioned, however, that Amos E. Dolbear, of Tufts College, Massachusetts, and Thomas A. Edison, of Menlo Park, New Jersey, likewise succeeded in solving the difficulty in the way of telephonic communication, and in answering practically several of the minor questions that hindered at first the complete success of the invention. The telephone is an instrument for the reproduction of sounds, particularly the sounds of the human voice, by the agency of electrical conduction at long distances from the origin of the vocal disturbance. Or it may be defined as an instrument for the _transmission_ of the sounds referred to by the agencies described. Indeed it were hard to say whether in a telephonic message we receive a _reproduced_ sound or a _transmitted_ sound. On the whole, it is more proper to speak of a reproduction of the original sound by transmission of the waves in which that sound is first written.

It is now well known that the phenomenon called sound consists of a wave agitation communicated through the particles of some medium to the organ of hearing. Every particular sound has its own physical equivalent in the system of waves in which it is written. The only thing, therefore, that is necessary in order to carry a sound in its integrity to any distance, is to transmit its physical equivalent, and to redeliver that equivalent to some organ of hearing capable of receiving it.

Upon these principles the telephone was produced--created. Every sound which falls by impact upon the sheet-iron disk of the instrument communicates thereto a sort of tremor. This tremor causes the disk to approach and recede from the magnetic pole placed just behind the diaphragm. A current of electricity is thus induced, pulsates along the wire to the other end, and is delivered to the metallic disk of the second instrument, many miles away, just as it was produced in the first. The ear of the hearer receives from the second instrument the exact physical equivalent of the sound, or sounds, which were delivered against the disk of the first instrument, and thus the utterance is received at a distance just as it was given forth.

As already said, the invention of the telephone stands chiefly to the credit of Professors Gray and Bell. It should be recorded that as early as 1837, the philosopher Page succeeded, by means of electro-magnetism, in transmitting _musical_ tones to a distance. It was not, however, until 1877 that Professer Bell, in a public lecture given at Salem, Mass., astonished his audience, and the whole country as well, by receiving and transmitting _vocal_ messages from Boston, twenty miles away. Incredulity had no more a place as it respected the feasibility of talking to persons at a distance. The experiments of Gray at Chicago, a few days later in the same month, were equally successful. Messages were distinctly delivered between that city and Milwaukee, a distance of eighty-five miles, nor could it be longer doubted that a new era in the means of communication had come.

The Bell telephone, with its many modifications and improvements, has come into rapid use. Within reasonable limits of distance, the new method of transmitting intelligence by direct vocal utterance, has taken the place of all slower and less convenient means of intercommunication. The appearance of the simple instrument has been one of the many harbingers of the oncoming better time, when the interchange of thought and sentiment between man and man, community and community, nation and nation, and race and race shall be the preliminary of universal peace in the world and of the good-fellowship of mankind.

Every such fact as the invention of the telephone, produces a complex and almost indescribable result in human society. This result has in it, in the first place, a change in the manners and method of the individual There is also a change in his sentiments. He whose work in life, whatever it may be, is accomplished in touch with the telephone will realize that he is in touch with the whole world. This intimacy reaches, first, his neighbors and friends. He seems to live henceforth in their presence, and in communication with them.

The isolation of the individual life is virtually obliterated by such an agency. Solitude disappears before it; for he whose ear is within hearing of his instrument, knows not at what moment any one of many thousands of people may speak to him. He knows not at what moment intelligence of an ever-varying kind may be spoken to him from his own community or out of the depths of distance. The mind is thus affiliated with an enlarged and ever-present society. These considerations do not relate to mere matters of convenience and quickness and advantage and safety, but to the larger question of the aggregate effect upon the individual.

The effect on the community is of like kind. The community is no longer so segregated as it was before. The community is in touch with other communities of like character. The conflagration in one town is felt in the neighboring towns, if it is not seen. The epidemic of the one is the epidemic of many. The sensation of the one community diffuses itself instantly into several. The effect is in the intellectual life like that of a wave produced on the lake by the casting in of a stone. The wave widens and recedes. It may be obstructed or unobstructed in its progress. If obstructed, the obstructions may be removed. Then the motion of the wave will become free and regular. So also on the tide of public thought. The telephone is an agency _for removing mental obstructions_, and for the regular diffusion of a common thought.

All this, however, is attended with draw-backs. One of these is the breaking in on the privacy and seclusion of the individual life. Individuality suffers under scientific progress. Great thinking is accomplished best in solitude. Emerson has forcibly pointed out the advantages which arise in the intellectual life from its isolation and seclusion--from its free and uninterrupted communion with itself.

The convenience--the physical convenience--of life is vastly augmented by such a contrivance as the telephone. Time is saved and trouble obviated. But at the same time the necessity for bodily exercise is reduced, and the overgrowth of brain at the expense of body encouraged. The fact is that the invention of the telephone and its general use, while it has added very greatly to the comfort of life, while it has promoted ease and diffused a social sense that needed stimulation and development, has at the same time brought in conditions that are not wholly favorable to human welfare. More largely still, the truth is that the telephone, like every other symbol and agency of progress, has brought _enlarged responsibilities._

No man, no community, no people or nation can gain an increase of power without accepting the accompanying increase of responsibility. The moral nature of man is thus involved. Every forward stride of scientific invention places upon the life of man, including his bodily activity, his mental moods and his spiritual and moral powers, an added stress of duty, of energy, and of rectitude in conduct from which he may not shrink if he would be the gainer rather than the loser. Each discovery and each improved method of employing the beneficent forces of the natural world, brings with it a strain upon the moral nature of man which, if he stand it, well; but if he stand it not, then it shall go ill with him.

THE MACHINE THAT "TALKS BACK."

The invention for making nature give an intelligent response may well be regarded with wondering interest. The odd, we might say humorous, feature of the invention is that nature, being as it were cornered and compelled to respond, will answer nothing except _to repeat what is said in her ear!_ The phonograph may be defined as a mechanical parrot. Unlike the living bird, however, it never makes answers malapropos. It never deviates from the original text. The distrust which has been justly cherished against the talking bird on account of his originality can never be reasonably directed against the phonograph!

The possibility of writing sound has been recognized for a century past. Since the discovery of the vibratory character of sound, the physicist has seen the feasibility of recording the vibration. Nature herself has given many hints along this line of experimentation. Long ago it was seen that the writing sand sprinkled on the sounding board of the piano would under the influence of a chord struck from the keys arrange itself in geometrical figures. It was also seen that a discord sounded from the key-board would break the figures into chaos and confusion. Were not these phenomena sufficient to suggest that sound might be written in intelligible characters?

The mind, however, moves slowly from the old to the new. The former concept of physical facts and the laws which govern them is not readily given up. A great discovery in physical science seems to disturb the foundations of nature. It does not really do so; the disturbance is not in nature, but in the mind. No endeavor of man, no advance of his from some old bivouac to a new camping-ground, affects in the least the order of the world. The change, we repeat, is in the man, and in the race to which he belongs.

Long and tedious has been the process of getting thought into a recorded form. The first method of expressing thought was oral. Long before any other method of holding ideas and delivering them to others was devised or imagined, speech came. Speech is oral. It is made of sound. Oral utterance is no doubt as old as the race itself. It began with the first coming of our kind into this sphere. Indeed we now know that the rudiments of speech exist in the faculties of the lower animals. The studies of Professor Garner have shown conclusively that the humble simian folk of the African forest have a speech or language. Of this the professor himself has become a student, and he claims to have learned at least sixty words of the vocabulary!

Strange it is to note the course which linguistic development has taken. At the first, there was a _spoken_ language only. The next stage was to get this spoken language recorded, not in _audible_, but in _visible_ symbols. Why should it have been so easy and apparently natural for the old races to invent a visible form of speech-writing rather than an audible form? Why should the ancients have fallen back on the eye rather than the ear as the sense to be instructed? Why should sight-writing have been invented thousands of years ago, and sound-writing postponed until the present day?

In any event, such has been the history of recorded language. The early races began as the mother begins with her children; that is, with oral speech. But at a certain stage this method was abandoned, and teachers came with pictorial symbols of words. They invented visible characters to signify words, syllables, sounds. Thus came alphabetical writing, syllabic writing, verbal writing, into the world. Ever afterward the children of men learned speech first from their parents, by oral utterance; but afterward by means of the pictorial signs in which human language was recorded.

This method became habitual. The eye was made to be the servant of the intellect in learning nearly all that was to be gained from the wisdom of the past. It was by the tedious way of crooked marks signifying words that ideas were henceforth gleaned out of human lore by all who would learn aught from the recorded wisdom of mankind. And yet there never was anything essentially absurd or insurmountable in the invention of a method of recording speech in audible instead of visible symbols.

The phonograph came swiftly after the telephone. The new instrument is in a sense the complement of its predecessor. Both inventions are based upon the same principle in science. The discovery that every sound has its physical equivalent in a wave or agitation which affects the particles of matter composing the material through which the sound is transmitted led almost inevitably to the other discovery of _catching_ and _retaining_ that physical equivalent or wave in the surface of some body, and to the reproduction of the original sound therefrom.

Such is the fundamental principle of the interesting but, thus far, little useful instrument known as the phonograph. The same was invented by Thomas A. Edison, of Menlo Park, in the year 1877. The instrument differs considerably in structure and purpose from the _Vibrograph_ and _Phonautograph_ which preceded it. The latter two instruments were made simply to _write_ sound vibrations; the former, to reproduce _audibly_ the sounds themselves.

The phonograph consists of three principal parts,--the sender or funnel-shaped tube, with its open mouth-piece standing toward the operator; the diaphragm and stylus connected therewith, which receives the sound spoken into the tube; and thirdly, the revolving cylinder, with its sheet-coating of tin-foil laid over the surface of a spiral groove to receive the indentations of the point of the stylus. The mode of operation is very simple. The cylinder is revolved; and the point of the stylus, when there is no sound agitation in the funnel or mouth-piece, makes a smooth, continuous depression in the tin-foil over the spiral groove. But when any sound is thrown into the mouth-piece the iron disk or diaphragm is agitated; this agitation is carried through the stylus and written in irregular marks, dots, and peculiar figures in the tin-foil over the groove.

When the utterance which is to be reproduced has been completed, the instrument is stopped, the stylus thrown back from the groove, and the cylinder revolved backward to the place of starting. The stylus is then returned to its place in the groove, and the cylinder is revolved forward at the same rate of rapidity as before. As the point of the stylus plays up and down in the indentations and through the figures in the tin-foil, produced by its own previous agitation, a quiver exactly equivalent to that which was produced by the utterance in the mouth-piece is thrown into the air. This agitation is of course the exact physical equivalent of the original sound, or, more properly, _is_ the sound itself. Thus it is that the phonograph is made to talk, to sing, to cry; to utter, in short, any sound sufficiently powerful to produce a perceptible tremor in the mouth-piece and diaphragm of the instrument.

Much progress has been made toward the utilization of the phonograph as a practical addition to the civilizing apparatus of our time. It may be said, indeed, that all the difficulties in the way of such a result have been removed. Mr. Edison has carried forward his work to such a degree of perfection that the instrument may be practically employed in correspondence and literary composition. The problem has been to _stereotype_, so to speak, the tin-foil record of what has been uttered in the mouth-piece, and thus to preserve in a permanent form the potency of vanished sounds. Nor does it require a great stretch of the imagination to see in the invention of the phonograph one of the greatest achievements of the age--a discovery, indeed, which may possibly revolutionize the whole method of learning.

It would seem clear that nature has intended the _ear_, rather than the eye, to be the organ of education. It is manifestly against the fitness of things that the eyes of all mankind should be strained, weakened, permanently injured in childhood, with the unnatural tasks which are imposed upon the delicate organ. It would seem to be more in accordance with the nature and capacities of man, and the general character of the external world, to reserve the eye for the discernment and appreciation of beauty, and to impose upon the ear the tedious and hard tasks of education.

The phonograph makes it possible to read by the ear instead of by the eye, and it is not beyond the range of probability that the book of the future, near or remote, will be written in phonographic plates and made to reveal its story directly to the waiting ear, rather than through the secondary medium of print to the enfeebled and tired eye of the reader.

We hardly venture on prophecy; but we think that he who returns to this scene of human activity at the close of the twentieth century will find that sound has been substituted for sight in nearly everything that relates to recorded information, to learning, and to educational work. By that means the organ of hearing will be restored to its rightful office. Enlightenment and instruction of all kinds will be given by means of phonographic books. The sound-wave will, in a word, be substituted for the light-wave as the vehicle of all our best information and intercourse. The ear will have habitually taken the place of the eye in the principal offices of interest and information.

The unnatural method of the book--the visible book instead of the audible book--will then be done away. Nature, who instructs the child by sound, will continue to teach the man in the same manner. All mothers, from the mother bird to the mother woman, begin the teaching of their offspring by sound, by utterance. The mother bird continues in this manner; but the mother woman is presently supplanted by a teacher who comes in with a printed book filled with crooked marks, and would have it that learning must be _thus_ acquired. Instead of continuing the natural process of instruction to the complete development and information of the mind, an abnormal method has been adopted by mankind with many hurtful consequences.

The youth at a certain age is led into the world of science, and there dismissed from the mother-method, to acquire, if he can, the painful and tedious use of meaningless hieroglyphics. There he must study with the eye, learning as best he may the significance of the crooked signs which can at the most signify no more than words. How much of human energy and life and thought have been thus wasted in the instruction of the mind by characters and symbols. The eyes of mankind have, as we said, been dimmed and shadowed, and at the same time the faculties have been overheated and the equipose of perception and memory seriously disturbed by this unnatural process of learning.

Human beings begin the acquirement of knowledge with words, and they end with words; but an unnatural civilization has taught man to walk the greater part of his intellectual journey by means of arbitrary systems of writing and printing. When the next Columbian Year arrives we shall see him untaught (a hard thing withal) and retaught on nature's plan of learning. Nature teaches language by sound only. Artificiality writes a scrawl. Nature's book is a book of words. Man's book is as yet a book of signs and symbols. Nature's book utters itself to the ear, and man's book blinds the eyes and overheats the imagination. Nature's method is to teach by the ear, and to reserve the sight for the discovery and enjoyment of beauty.

The sound-book in some form is coming; and with that the intellectual repose of mankind will begin to be restored. The use of the eye for the offices of education instead of the stronger ear, has, we think, impaired, if it has not destroyed, the equilibrium of the human mind. That equilibrium must be restored. The mental diseases and unrest of our race are largely attributable to the over-excitement of the faculties through ages of too much seeing.

The Age of Hearing is, we think, to be ushered in with the twentieth century. The coming of that age will tend to restore the mental balance of mankind. Memory, now almost obliterated, will come again. The over-heated perceptions will cool. The imagination will become calm, and the eye itself will recover, we hope, from the injuries, of overstrain, and will regain its power and lustre. Man will see once more as the eagle sees, and will learn Shakespeare by heart. He will remember all knowledge, and will again be able to see, as of old, from Sicily to Carthage!

THE EVOLUTION OF THE DYNAMO.

BY PROFESSOR JOSEPH P. NAYLOR, A.M.

It is difficult to estimate the influence in modifying and shaping the nineteenth century civilization that has resulted from the discovery of the dynamo and the production of heavy currents of electricity. That it has had great influence is evident without question. The arc light for out-of-doors lighting and the incandescent lamp for inside has modified all our previous ideas of illumination. Effects in light are now produced daily that were beyond imagination twenty years since. The trolley and the electromoter have largely solved the problem of rapid transit through our crowded cities. Thus larger business facilities, suburban homes and cheaper living, cleanliness and better sanitary conditions are electrical results.

The transmission of energy by the electric current from a central plant makes possible many small industries that could not exist without it, and gives employment and happiness to hundreds. The art of Electro-metallurgy seems but the development of months: yet it already employs millions of capital and is adding thousands daily to the world's wealth. Steam and wind and tide contribute to the work. Even Niagara is being touched by the spirit of the time and sends her wasting energy thrilling through the electric wires to turn the wheels of many busy factories. It is perhaps not the least remarkable fact in connection with this work that it is largely the product of the last thirty years, and that it had its very beginning less than seventy years since. Edison and Thompson and Brush are honorable household names; yet they are still living to produce even greater electric marvels. In fact, so rapid and brilliant has been the development that in the brilliancy some of the pioneers in the work have been almost forgotten, except by the specialist and the student, and it is no small part of this sketch to do them honor. The tiny spark of Faraday may be lost in the brilliancy of the million-candle-power search-light, yet the brilliancy of the search-light but enhances the wonder of the discovery of the spark.

The discovery of electro-magnetic induction marked the beginning of a new era; for in it lay all the possibilities of the future of electrical science. Michael Faraday, the third son of a poor English blacksmith, was born at Newington, Surrey, England, September 3, 1791. His father's health was never the best, and due to the resulting straitened circumstances his early education consisted of the merest rudiments of reading, writing and arithmetic. His early life was, no doubt, largely spent in the street; but at thirteen he became errand boy to a book-seller of London. About a year later he was apprenticed to a book binder, with whom he served seven years, learning the trade.

It was while an apprentice that Faraday began reading scientific articles on chemistry and physics in the books he was set to bind. He also tried to repeat the experiments of which he read. And more, he pondered over them long and earnestly, until he saw clearly the principles involved in them. It was in these early days of experimenting and self-education that the desire to become a philosopher was implanted in his mind. He embraced every chance for scientific study and caught every opportunity for intellectual self-improvement. In the last year of his apprenticeship he was enabled through the kindness of a customer at his master's shop, to attend a course of four lectures on chemistry, given by Sir Humphry Davy at the Royal Institution. This marked the turning point in his life. He made careful notes of the lecture, and afterward transcribed them neatly into a book and illustrated them with drawings of the apparatus used.

After completing his apprenticeship, Faraday began life as a journeyman bookbinder. He had, however, as he says, "no taste for trade." His love of science became a consuming desire that he sought in every way to gratify. Inspired by his longing for scientific pursuits, he sent his lecture notes to Sir Humphry Davy, with the request that if opportunity offered he would give him employment at the Royal Institution. Davy was favorably impressed with the lecture report, and sent a kindly reply to the young philosopher. Shortly after this a vacancy did happen to occur at the Institution, and upon the recommendation of Davy, Faraday was elected to the place. Thus, in 1813, in the humble capacity of an assistant charged with the simple duty of dusting and caring for the apparatus, Michael Faraday began the life that was destined to make him the first scientist of the world and to bring honor to the Institution which had given him his opportunity.

There is inspiration and encouragement to be found in reading the story of Faraday's success. He has been called a genius; but his genius seems to have largely consisted in persistent industry and the habit acquired in those early days of thinking over his experiments and reading until he had a clear perception of all there was in them. He lived in his work, and loved it. In the fifty busy years that followed his installment at the Royal Institution he digged deep into nature's secrets, and gave the world many brilliant gems as evidence of his industry. But of all his discoveries, _electro-magnetic induction_ is the crowning masterpiece and that for which the world stands most his debtor.

The principle of conservation of energy, now so well known and universally accepted, was then but a vague guess in the minds of the more advanced in science. Faraday was among the first to accept the new doctrine, and many of his brilliant discoveries were made in his effort to prove the truth of these important generalizations. He was acquainted with Sturgeon's method of making magnets by sending a current of electricity through a wire wound around a bar of iron; and he reasoned, if electricity will make a magnet, a magnet ought to make electricity. As early as 1821 his note book contains this suggestion: "Convert magnetism into electricity." Again and again he attacked the problem; but it was not until the autumn of 1831 that his efforts to solve it were successful. Then in a series of experiments that have scarcely ever been equaled in brilliancy and originality, he gave to the world the principle on which is based the wonderful development of modern electrical science.

The principle is briefly stated. The space, around a wire carrying an electric current, or in the neighborhood of a magnet, has a directive effect upon a magnetic needle, and is hence called a magnetic field. Now if a conductor, or coil of wire, be placed in the field across the direction of a magnetic needle, and the field be varied either by varying the current or moving the magnet, a current will be developed in the conductor. It is impossible at this distance to appreciate the interest excited by the announcement of this principle, not only among scientists, but also among inventors and those who saw practical possibilities for the future; and probably no one more fully appreciated its value than Faraday himself. Yet he made no effort to develop it further, or even to protect his interest by a patent, as is common in these days. He was eminently a scientist, and this was his free gift to the world. He said: "I have rather been desirous of discovering new facts and relations than of exalting those already obtained, being assured the latter would find their full development hereafter."

Among the first to attempt successfully to exalt the new discovery was Pixii, an instrument maker of Paris, in 1832. He wound two coils of very fine insulated wire upon the ends of a piece of soft iron, bent in a horseshoe form. A permanent horseshoe magnet was then placed with poles very close to the ends of the iron in the coils. The field so produced was then rapidly varied by revolving the magnet on an axis parallel to its length. The soft iron cores of the coils became strongly magnetized as the poles of the revolving magnet came opposite to them; and their polarity was reversed at each half-revolution of the magnet. By this plan currents of considerable intensity and alternating in direction at each revolution were induced in the coil.

The ends of the coil were next connected to the external circuit through a "commutator." This is a device which is arranged to convert the alternating current of the coils into a current of one direction in the external circuit, and which in some form is found on all direct-current dynamos. Joseph Saxton, an American, improved upon Pixii's machine by rotating the coils, or armature as it is called, and making the heavier magnet stationary. The essential points of construction being worked out, improvements followed rapidly. Dr. Werner Siemans, of Berlin, introduced an important modification by making the revolving armature of a cylinder of soft iron, having a groove cut throughout its length on opposite sides. In these grooves a wire was wound and the armature was rotated on its axis between the poles of several magnets.

In all the earlier machines permanent magnets of steel were used. The next important step was to use electro-magnets of soft iron, excited by a current flowing through many turns of wire wound around the legs of the magnet. These could be made much more strongly magnetic than the permanent magnets. The exciting current was at first obtained from a small permanent magneto machine; but it was afterward found that the machine could be made self-exciting. Soft-iron electro-magnets, after being once magnetized, remain slightly magnetic. This will produce a weak current in the revolving armature which is turned into the magnet coils. The magnets are thus further magnetized, and again react upon the armature with greater intensity. In this way a _strong_ current is rapidly built up, and after wholly or in part passing around the magnet coils to sustain its magnetism, can be carried out into the circuit to serve the great variety of purposes to which it is now put.

The essential points in the evolution of the dynamo can here be sketched only in broadest outline. Even to catalogue in detail, the improvements of Edison and Brush, Gramme and Wheatstone, and a host of others who have contributed to the work, would require a volume. One fact, however, should ever be kept in mind: Whatever may be the extent of the superstructure of electrical science, it is all built upon the foundation of electro-magnetic induction laid by Michael Faraday. The little "magnetic spark" he first produced, and the trembling of his galvanometer-needle, were but signals of the birth of the giant of the century.

These are the days of electricity and steel, and a fitting part of the intense age in which they exist. That we have as yet seen but a partial development of the possibilities of the electrical discovery, no one can doubt. The rush of the trolley car, and the blinding flash of the electric light, are but challenges thrown out to the future for even greater achievements. That they will come no one will question; but where is the daring prophet who will hazard a guess as to what they will be?

THE UNKNOWN RAY AND ENTOGRAPHY.

It is difficult to name the unknown. In the ancient world all the unknown was included in the idea of God. It remained for the evangelist to declare that God is a _spirit_--thus separating the natural forces of the material world from the Supreme Power who is from eternity.

This century has been the epoch of investigation into the nature of the imponderable forces. Sound and light and heat have been known as the principal agents of sensation since the first ages of man-life on the earth; but their nature has not been well understood until within the memories of men still living. Electricity was also vaguely known--but very indistinctly--from ancient times. It has remained for the scientific investigators of our age to enter into the secret parts of nature and lay bare to the understanding many of the hitherto unknown facts relating to the imponderable agents.

The laws of heat, of acoustics, of light, have been clearly arranged and taught; but they have not been placed beyond the reach of new interpretation and possibly not beyond the reach of complete revolution and reconstruction. That which has been accepted as definitely known with regard to these agents has now to be reviewed, and possibly to be learned over again from first principles.

As to electricity in its various forms and manifestations, that sublime and powerful agent began to be better known just before the middle of the century. Since that time there has been almost constant progress in the science of this great force, until at the present time it is handled, controlled and understood in its phenomena almost as easily as water is poured into a vessel, air compressed under a piston, or hydrogen made to inflate a balloon.

It has remained, however, for the last half decade of the great century to come upon and investigate a hitherto unknown force in nature. Certain it is that the new force exists, that it is everywhere, that it is a part of the profound agency by which life is administered, that its control is possible, and that its probable applications are as wonderful--perhaps more wonderful--than anything ever hitherto discovered by scientific investigation.

It is not unlikely that since the day, or evening, on which Galileo, with his little extemporized telescope, out in the garden of the Quirinal, at Rome, compelled bigotry to behold the shining horns of the crescent Venus, thus opening as if by compulsion the sublime vista of the heavens and bringing in a new concept of the planetary and stellar worlds,--no such other discovery as that of the so-called Röntgen rays has been made. The results which seem likely to flow from this marvelous revelation surpass the human imagination. Let us try in a few words to realize the discovery, and define what it is.

It was on the eighth of November, 1895, that Dr. William Konrad Röntgen, of Würzburg, made the discovery which seems likely to contribute so much to our knowledge of the mysterious processes of nature. On that day Dr. Röntgen was working with a Crookes tube in his laboratory. This piece of apparatus is well known to students and partly known to general readers. It consists of a glass cylinder, elongated into tubular form, and hermetically closed at the ends. When the tube is made, the air is exhausted as nearly as possible from it, and the ends are sealed over a vacuum as perfect as science is able to produce. Through the two ends, bits of platinum wire are passed at the time of sealing, so that they project a little within and without. The interior of the tube is thus a vacuum into which at the two ends platinum wires extend. Electrical communication with outside apparatus is thus supplied.

It has long been known that on the discharge of an electrical current into this kind of vacuum peculiar and interesting phenomena are produced. The platinum wires at the two ends are connected with the positive and negative wires or terminals of an induction coil. When this is done, the electrical current discharged into the vacuum seems to flash out around the inner surfaces of the tube, in the form of light. There are brilliant coruscations from one end to the other of the tube. The tips of the platinum wire constituting the inner poles glow and seem to flame. That pole which is connected with the positive side of the battery is called the _anode_, or _upper_ pole, and that which is connected with the negative, or receptive, side of the battery, is called the _cathode_, or lower pole. It was in his experimentation with this apparatus, and in particular in noticing the results at the cathode or lower end of the tube, that Professor Röntgen made his famous discovery. It was for this reason that the name of "cathode rays" has been given to the new radiant force; but Dr. Röntgen himself called the phenomena the X, or unknown, rays.

In the experimentation referred to, Röntgen had covered the glass tube at the end with a shield of black cardboard. This rendered the glow at the cathode pole completely invisible. It chanced that a piece of paper treated with platino-barium cyanide for photographic uses was on a bench near by. Notwithstanding the fact that the tube was covered with an opaque shield, so that no _light_ could be transmitted, Professor Röntgen noticed that changes in the barium paper were taking place, _as though_ it were exposed to the action of light! Black lines appeared on the paper, showing that the surface was undergoing chemical change from the action of some invisible and hitherto unknown force!

This was the moment of discovery. The philosopher began experimenting. He repeated what had been accidentally done and was immediately convinced that a force, or, as it were, invisible rays were streaming from the cathode pole of the tube through the glass, and through a substance absolutely opaque, and that these rays were performing their work at a distance on the surface of paper that was ordinarily sensitive only to the action of light.

Certain it was that _something_ was doing this work. Certain it was that it was _not light_. Highly probable it was that it was not any form of _electricity_, for glass is impermeable to the electrical current. Certain it was that it was _not sound_, for there was no noise or atmospheric agitation to produce such a result. In a word, it was demonstrated then and there that a hitherto unknown, subtle and powerful agent had been discovered, the applications of which might be of almost infinite range and interest.

Professor Röntgen soon announced his discovery to the Physico-Medical Society of Würzburg. It was at the December meeting of this body that the new stage in human progress was declared. The news was soon flashed all over the world, and scientific men in every civilized country began at once to experiment with the cathode light--if light that might be called that lighted nothing.

In Röntgen's announcement he stated that there had been by the scientists Hertz and Lenard, in 1894, certain antecedent discoveries from which his own might in some sense be deduced. There was, however, a great difference between the discovery made by Röntgen and anything that had preceded it. His stage of progress in knowledge was this, that during the discharge of _one_ kind of rays of force from the cathode pole in a Crookes tube _another kind_ of rays are set free, which differ totally in their nature and effects from anything hitherto known. It is this fact which has indissolubly connected the name of Konrad Röntgen with that great bound in scientific knowledge which seems likely to modify nearly all the other scientific knowledge of mankind.

Everywhere, in the first months of 1896, the experimenters went to work to verify and apply the discovery of the German philosopher. It was at once discerned that the new force, since it would freely traverse opaque bodies and produce afterward chemical changes on sensitized surfaces similar to those ordinarily produced _by_ light, might be used for delineating (we can hardly say _photo_ graphing) the interior outlines and structure of opaque bodies!

On this line of experimentation the work at once began, and with remarkable success. Röntgen himself was the first man in the world to obtain, as _if_ by photography, the invisible outline of objects through opaque materials. He soon obtained a delineation of the bones of a living hand through the flesh, which was only dimly traced in the resulting picture. In like manner coins were delineated through the leather of pocketbooks. Other objects were pictured through intervening plates of metal or boards of wood. The possibility of discovering the visible character of invisible things, and even _of seeing directly through_ opaque materials into parts where neither light nor electricity can penetrate, was fully shown.

The work of picture taking in the interior of bodies and through opaque materials was quickly taken up by philosophers in England, France and the United States. Almost everywhere the physical laboratories witnessed daily this form of experimentation. Swinton, of London; Robb, of Trinity College, Dublin; Morton, of New York; Wright, of Yale University, and in particular Thomas A. Edison, of Menlo Park, attacked the new problem with scientific zeal, and with startling results. It remained for Edison to discover that the new force acted in some respects in the manner of _sound_ rather than in the manner of _light_. Thus, for example, he showed that the invisible rays not only _pass through_ substances that are opaque to light and non-conductors of electricity, but that the invisible rays _run around the edges and sides_ of plates, then proceeding on their way somewhat in the manner of sound. A sound made on one side of a metallic plate is heard on the other side _partly_ by transmission through the plate, and _partly_ by going around the edges, by atmospheric transmission. The new force rays act in this manner, and Edison is said to have procured pictures by means of the invisible agent while it was _going around the corner _ of an opaque obstruction!

The pre-eminence of Thomas A. Edison as a scientific explorer and inventor depends upon a quality of mind which enables him more easily than others--more distinctly than any others--to see the touch of each new discovery with existing conditions, and the application of it to the problems of life. Edison catches the premonitory spark struck in the darkness by some other master's hammer, and with that kindles a conflagration. Though not the discoverer of the Röntgen ray, he was able, as it would appear, to understand that discovery better even than the discoverer. He almost immediately applied the new increment of knowledge more successfully, we think, than any contemporary scientist. His experimentation led him directly to the discovery of the important fact that no photographic apparatus of any kind is needed to enable an observer to use the X-rays in the delineation or inspection of objects through opaque substances. He said within himself: "Why not pass the X-rays through the object to be inspected and then convert them into visibility, as if by fluorescence."

This scientific question Edison almost immediately solved. Fluorescence is a property which some transparent bodies have of producing, either on their surface or within their substance, light different in color from that of its origin. This happens, for example, when _green_ crystals of fluor spar afford _blue_ reflections of light. Glass may be rendered fluorescent, as is seen in the Geisler and Crookes tubes. Edison conceived the project of using this phenomenon to get back the invisible rays into visibility.