Nikola Tesla's 1893 lecture in St. Louis (MO) for 5000 people

Darko Žubrinić, Zagreb, 2022

Iron County Register, March 09, 1893

Image provided by: State Historical Society of Missouri; Columbia, MO


The title of the following article published in St. Louis (An evening with the Montenegrin Electrical Wizard, as well as once in the text - young Montenegrin) is, we believe, closely related to the fact that Tesla knew by heart the verses of "Gorski vijenac" (The Mountain Wreath) written by Petar Petrović Njegoš, Montenegrin poet and statesman.


An Evening with the Montenegrin Electrical Wizard.

Marvellous Demonstrations, which Reveal the Fact that the Application of Electricity is As Yet to Its Infancy.

St. Louis, March 2. - Seldom has the Grand Music hall in the exposition building been so densely crowded as last night, when Nikola Tesla gave a lecture and demonstration illustrative of his latest achievements in the way of electrical experiments. Five thousand tickets of admission had been issued, and as invitations had been limited to members of the leading clubs and other prominent citizens it goes without saying that the gathering was a very magnificent and representative one.

Nikola Tesla.

Mr. Tesla's apparatus is of an apparently simple character. A plain deal table, very strongly constructed and some twenty feet long, contained the induction coils, disks and general apparatus, while on a smaller table were arranged a large number of vacuum bulbs, in appearance resembling the incandescent light bulbs in use for commercial and private purposes. On the left of the table was a very handsome circlet, brilliantly illumined and bearing the words: "St. Louis Electric Ex., 1893," worked around its border.

At about 8:30 o'clock between twenty and thirty of the leading electricians in the city in attendance on the electrical convention marched on the stage occupied seats at a safe distance from the experiment table, and a moment or two later President [of Missouri, DŽ] Ayer introduced the lecturer, obeying the wishes expressed him by Nikola Tesla and introducing him as such, without the prefix of either mister or professor.

The lecture and demonstration themselves were of a nature which had to be seen to be appreciated. The young lecturer responded in a pleasing manner to the gratifying reception given him, and proceeded at once with his address. Unlike many scientific lecturers who derive satisfaction from using long words when addressing unscientific audiences, and leaving them in doubt as to what is meant, Nikola Tesla appeared to be almost nervously anxious to make himself understood by the ladies and gentlemen before him, and those who had read of his marvellous achievements experienced little difficulty in following his line of thought through the evening.

Before going into the question of incandescent and phosphorescent light, the young Montenegrin [sic! DŽ] expert referred at some length to the connection between nature and electricity, and to the boundless force yet undeveloped, but in the near future to be brought under the control of man. He passed on to give a very pleasing summary of the value of the human eye, which he compared with the various other senses. Passing from sight to light the lecturer said that this brought him right to the subject he wished to bring before a St. Louis audience. He would abstain, as far as possible, from introducing purely scientific terms, and would, by the aid of the apparatus which was in view of the audience, produced a cluster in a manner hitherto deemed impossible. Turning Mr. Ayer, Mr. Tesla said:

"Lights out, please."

The order was obeyed instantly, and for a moment there was a slight buzz of excitement, as the spectators and listeners found themselves in absolute darkness.

"If I have not made a mistake," went on Mr. Tesla, "I will now show you a phenomena which only scientific men can appreciate the greatness of. Pardon me if I do not do all I would wish, because it is so difficult to obtain the proper conditions in a large hall like this for an experiment of this delicate character."

There was a pause of a few seconds; Tesla stood, dark and smiling, behind his rude workbench and with his wizard touch made the darkness luminous with the trembling, zigzag flashes of gold and blue and purple light. In the experiment showing the effects of electrostatic force a small apparatus especially devised for the purpose was attached to the electric current, and Tesla seized the wires with a pair of iron and pliers, and at once there emanated from his finger tips a slimy haze of red and blue fire, and sparks leaped form point to point, "strong enough it might be to knock him down, but not to kill," as he explained, or it would interrupt his experiment. Then trembling lines of foggy light were sent streaming from the apparatus to a brass sphere. Then two copper plates of disks were set in action six inches apart and the light sent in distinct and vivid lines from one to the other as though attached together by molten wires. The effect was startling in the darkness, and aided by the ghoulish glee of the rumbling dynamo made a scene of appalling splendour.

"If the energy had been propelled directly it would have killed, and if I were to try the experiment of direct energy you would not be able to see any of the interesting things I am going to try and show you." The audience appreciated the situation fully and laughed heartily at the remark; and the laughter was renewed with double force when some eight or ten of the gentlemen of the stage crept quietly back to their seats, out of which they had evidently been scared during the mysterious and somewhat noisy experiment. This portion of the lecture was of a strictly technical character, and most of the varying result were obtained by changing the bulbs used and increasing the power of the current and the frequency of the alternations.

Then came demonstrations of the ease with which Tesla can produce light by aid of one wire. He explained that it had always been regarded as necessary to produce electric light to have two wires, connecting one with one pole and the other with the other pole. He had found that it was quite possible to do it with only one wire, and producing an induction coil he proceeded to connect it with a single wire, on which he attached a bulb, from which the air had been extracted in the ordinary manner, and from which came a light at first faint and feeble, but under altered conditions, powerful, brilliant and finally dazzling. In some repeats even greater results were produced with the one wire than with the two, and the various reasons for this were listened to by the experts present with apparently great interest. When finally a light was produced from a single wire sufficient to light up the entire Marquette quite brilliantly, although the globe used was of the ordinary incandescent size, the delegates to the convention rose almost to a manned acknowledged the success of the experiment in a graceful and becoming manner.

Passing from the incandescent to the phosphorescent, Mr. Tesla proceeded to produce light without wires at all - that is to say, he produced a distant glow between two highly-charged disks without using a filament of any kind or any of the apparatus hitherto deemed indispensable for the purpose. An incandescent light, hung upon a single wire, but not connected with it, was made to produce an almost blinding red light, which by increasing the frequency of the alternations in the current, became finally white and powerful.

Mr. Tesla went on to pass electric currents through his body in a manner almost weird and certainly awful to the mind of those who have learned to regard electricity as a source of danger as well as profit to the human race. Taking a glass bulb in one hand and grasping a wire in the other the lecturer singled "lights out," and a second later the audience was both delighted and horrified to see the light emerge from the lecturer's hand.

A Weird Experiment.

The phosphorescent light thus produced lacks the dazzling whiteness of the incandescent and is somewhat green in appearance. But the light that apparently came out of the lecturer's body had sufficient illuminating power to make his hand and arm clearly visible, and when he raised the light and shook it several times the enthusiasm of the audience knew no bounds. As the lights were turned up the shouts of "bravo" came from parquet and balcony and from the experts close to the experimenter. The ladies waved their handkerchiefs, and several of the gentlemen were equally excited, and it was fully a minute before the lecturer could proceed.

Successful and wonderful as was this experiment it sank into insignificance compared with what followed. Taking in his hand a long glass tube, measuring three or four feet, the lecturer again connected himself with the powerful alternating current with his right hand, and the moment the lights were turned out the entire tube became phosphorescent. Standing on the stage with this illumined tube in his hand, the lecturer looked like some magician producing light, and a hum of admiration passed through the spectators. Next he put the tube high in the air and whirled it around his head several times. Then grasping it in the center, he twirled it to and fro much as the attendant at Donnybrook fair shakes his shillalah. This experiment was repeated again and again with increased power in the current until at last the vibrations were simply astounding and presented more the appearance of pyrotechnical display than anything else. The grandeur of the affair was increased by the knowledge that every particle of current creating or developing the light had to pass through the body of the lecturer himself.

Still more remarkable was the appearance of a globe attached to a wire ten or twelve inches long. Again connecting himself with the current Mr. Tesla seized one end of this wire and deliberately plated ball with the phosphorescent light, producing pyrations and other dazzling and astonishing effects. Then he took a oblong tube or wire very much resembling in size and shape a slate frame and this again he played with in pleasant, simple and unaffected manner. Throughout all these experiments the lecturer kept up a running comment, and seemed to be entirely unconcerned by the risks he appeared to be running. He admitted that when he first passed the current through his body he was somewhat alarmed, and he also mentioned the astonishment and amazement of an eminent English scientist to whom he made a demonstration before submitting the results to the public. Speaking of his triumphs he said: "I have been two or three times in my life recompensed for the trouble I have gone to. This was one of my recompenses, and I hope to have many more. You may see, perhaps, that there is no practical result in all this, but I am experimenting now in that direction, and have achieved more success than I can tell you tonight."

The next experiment was causing two wires, ten or twelve feet long, to phosphoresce over their entire length, and this experiment, shown in another phase, practically demonstrated the marvellous success of Tesla in producing a light strong enough for practical use without the aid of wires or exposed apparatus at all. It is not exactly bright, sliding light, such as that given by the arc lamp, or the pure white overpowering brilliancy of the incandescent, but the glow produced is a distinct light, good enough to enable a man to read by, although perhaps not quite comfortably. Mr. Tesla explained that the experiments in this direction were entirely crude and in their infancy, and although there was nothing in the lecture at all bordering upon boasting, there was a great deal of hope expressed as to what might be achieved in the future. Indeed, Mr. Tesla promised that in the early future he would produce light of this character on a commercial basis, and no one who witnessed the demonstrations and experiments last evening will be anxious to cross swords with the young inventor, or to dispute the possibility of his achieving any result he may desire or determine upon.

At the close of the lecture the young electrician was overwhelmed with congratulations to accept the hospitalities of prominent citizens and clubs, all of which he modestly declined, preferring the quiet and rest to be found at his hotel.

Iron County Register, March 09, 1893
Image provided by: State Historical Society of Missouri; Columbia, MO

Many thanks to dr. Ante Chuvalo for sending me the copy of the original article
about Nikola Tesla's lecture in St. Louis, Missouri, USA. DŽ

Exposition building in St. Louis (contaning the Grand Music hall), now the Public Library, in which Nikola Tesla delivered his lecture for more than 5000 people.

We provide an introductory part of Tesla's lecture, in which he describes the role of human eye. This seems to be one of the most beautiful texts honoring the eye ever written. We provide a translation of the original text into Croatian, using roughly the orthography that was in use in Croatia in the time of the appearance of the text in 1893.


On Light and Other High Frequency Phenomena

by Nikola Tesla

Franklin Institute, Philadelphia, February 24th, 1893

National Electric Light Association, St. Louis, March 1st, 1893


When we look at the world around us, on Nature, we are impressed with its beauty and grandeur. Each thing we perceive, though it may be vanishingly small, is in itself a world, that is, like the whole of the universe, matter and force governed by law, — a world, the contemplation of which fills us with feelings of wonder and irresistibly urges us to ceaseless thought and inquiry. But in all this vast world, of all objects our senses reveal to us, the most marvelous, the most appealing to our imagination, appears no doubt a highly developed organism, a thinking being. If there is anything fitted to make us admire Nature’s handiwork, it is certainly this inconceivable structure, which performs its innumerable motions of obedience to external influence. To understand its workings, to get a deeper insight into this Nature’s masterpiece, has ever been for thinkers a fascinating aim, and after many centuries of arduous research men have arrived at a fair understanding of the functions of its organs and senses. Again, in all the perfect harmony of its parts, of the parts which constitute the material or tangible of our being, of all its organs and senses, the eye is the most wonderful. It is the most precious, the most indispensable of our perceptive or directive organs, it is the great gateway through which all knowledge enters the mind. Of all our organs, it is the one, which is in the most intimate relation with that which we call intellect. So intimate is this relation, that it is often said, the very soul shows itself in the eye.

It can be taken as a fact, which the theory of the action of the eye implies, that for each external impression, that is, for each image produced upon the retina, the ends of the visual nerves, concerned in the conveyance of the impression to the mind, must be under a peculiar stress or in a vibratory state. It now does not seem improbable that, when by the power of thought an image is evoked, a distinct reflex action, no matter how weak, is exerted upon certain ends of the visual nerves, and therefore upon the retina. Will it ever be within human power to analyze the condition of the retina when disturbed by thought or reflex action, by the help of some optical or other means of such sensitiveness, that a clear idea of its state might be gained at any time? If this were possible, then the problem of reading one’s thoughts with precision, like the characters of an open book, might be much easier to solve than many problems belonging to the domain of positive physical science, in the solution of which many, if not the majority, of scientific men implicitly believe. Helmholtz has shown that the fundi of the eye are themselves, luminous, and he was able to see, in total darkness, the movement of his arm by the light of his own eyes. This is one of the most remarkable experiments recorded in the history of science, and probably only a few men could satisfactorily repeat it, for it is very likely, that the luminosity of the eyes is associated with uncommon activity of the brain and great imaginative power. It is fluorescence of brain action, as it were.

Another fact having a bearing on this subject which has probably been noted by many, since it is stated in popular expressions, but which I cannot recollect to have found chronicled as a positive result of observation is, that at times, when a sudden idea or image presents itself to the intellect, there is a distinct and sometimes painful sensation of luminosity produced in the eye, observable even in broad daylight.

The saying then, that the soul shows itself in the eye, is deeply founded, and we feel that it expresses a great truth. It has a profound meaning even for one who, like a poet or artist, only following his inborn instinct or love for Nature, finds delight in aimless thoughts and in the mere contemplation of natural phenomena, but a still more profound meaning for one who, in the spirit of positive scientific investigation, seeks to ascertain the causes of the effects. It is principally the natural philosopher, the physicist, for whom the eye is the subject of the most intense admiration.

Two facts about the eye must forcibly impress the mind of the physicist, notwithstanding he may think or say that it is an imperfect optical instrument, forgetting, that the very conception of that which is perfect or seems so to him, has been gained through this same instrument. First, the eye is, as far as our positive knowledge goes, the only organ which is directly affected by that subtile medium, which as science teaches us, must fill all space; secondly, it is the most sensitive of our organs, incomparably more sensitive to external impressions than any other.

The organ of hearing implies the impact of ponderable bodies, the organ of smell the transference of detached material particles, and the organs of taste, and of touch or force, the direct contact, or at least some interference of ponderable matter, and this is true even in those instances of animal organisms, in which some of these organs are developed to a degree of truly marvelous perfection. This being so, it seems wonderful that the organ of sight solely should be capable of being stirred by that, which all our other organs are powerless to detect, yet which plays an essential part in all natural phenomena, which transmits all energy and sustains all motion and, that most intricate of all, life, but which has properties such that even a scientifically trained mind cannot help drawing a distinction between it and all that is called matter. Considering merely this, and the fact that the eye, by its marvelous power, widens our otherwise very narrow range of perception far beyond the limits of the small world which is our own, to embrace myriads of other worlds, suns and stars in the infinite depths of the universe, would make it justifiable to assert, that it is an organ of a higher order. Its performances are beyond comprehension. Nature as far as we know never produced anything more wonderful. We can get barely a faint idea of its prodigious power by analyzing what it does and by comparing. When ether waves impinge upon the human body, they produce the sensations of warmth or cold, pleasure or pain, or perhaps other sensations of which we are not aware, and any degree or intensity of these sensations, which degrees are infinite in number, hence an infinite number of distinct sensations. But our sense of touch, or our sense of force, cannot reveal to us these differences in degree or intensity, unless they are very great. Now we can readily conceive how an organism, such as the human, in the eternal process of evolution, or more philosophically speaking, adaptation to Nature, being constrained to the use of only the sense of touch or force, for instance, might develop this sense to such a degree of sensitiveness or perfection, that it would be capable of distinguishing the minutest differences in the temperature of a body even at some distance, to a hundredth, or thousandth, or millionth part of a degree. Yet, even this apparently impossible performance would not begin to compare with that of the eye, which is capable of distinguishing and conveying to the mind in a single instant innumerable peculiarities of the body, be it in form, or color, or other respects. This power of the eye rests upon two things, namely, the rectilinear propagation of the disturbance by which it is effected, and upon its sensitiveness. To say that the eye is sensitive is not saying anything. Compared with it, all other organs are monstrously crude. The organ of smell which guides a dog on the trail of a deer, the organ of touch or force which guides an insect in its wanderings, the organ of hearing, which is affected by the slightest disturbances of the air, are sensitive organs, to be sure, but what are they compared with the human eye! No doubt it responds to the faintest echoes or reverberations of the medium; no doubt, it brings us tidings from other worlds, infinitely remote, but in a language we cannot as yet always understand. And why not? Because we live in a medium filled with air and other gases, vapors and a dense mass of solid particles flying about. These play an important part in many phenomena; they fritter away the energy of the vibrations before they can reach the eye; they too, are the carriers of germs of destruction, they get into our lungs and other organs, clog up the channels and imperceptibly, yet inevitably, arrest the stream of life. Could we but do away with all ponderable matter in the line of sight of the telescope, it would reveal to us undreamt of marvels. Even the unaided eye, I think, would be capable of distinguishing in the pure medium, small objects at distances measured probably by hundreds or perhaps thousands of miles.

But there is something else about the eye which impresses us still more than these wonderful features which we observed, viewing it from the standpoint of a physicist, merely as an optical instrument, — something which appeals to us more than its marvelous faculty of being directly affected by the vibrations of the medium, without interference of gross matter, and more than its inconceivable sensitiveness and discerning power. It is its significance in the processes of life. No matter what one’s views on nature and life may be, he must stand amazed when, for the first time in his thoughts, he realizes the importance of the eye in the physical processes and mental performances of the human organism. And how could it be otherwise, when he realizes, that the eye is the means through which the human race has acquired the entire knowledge it possesses, that it controls all our motions, more still, and our actions.

There is no way of acquiring knowledge except through the eye. What is the foundation of all philosophical systems of ancient and modern times, in fact, of all the philosophy of man? I am I think; I think, therefore I am. But how could I think and how would I know that I exist, if I had not the eye? For knowledge involves consciousness; consciousness involves ideas, conceptions; conceptions involve pictures or images, and images the sense of vision, and therefore the organ of sight. But how about blind men, will be asked? Yes, a blind man may depict in magnificent poems, forms and scenes from real life, from a world he physically does not see. A blind man may touch the keys of an instrument with unerring precision, may model the fastest boat, may discover and invent, calculate and construct, may do still greater wonders — but all the blind men who have done such things have descended from those who had seeing eyes. Nature may reach the same result in many ways. Like a wave in the physical world, in the infinite ocean of the medium which pervades all, so in the world of organisms, in life, an impulse started proceeds onward, at times, may be, with the speed of light, at times, again, so slowly that for ages and ages it seems to stay, passing through processes of a complexity inconceivable to men, but in all its forms, in all its stages, its energy ever and ever integrally present. A single ray of light from a distant star falling upon the eye of a tyrant in by-gone times, may have altered the course of his life, may have changed the destiny of nations, may have transformed the surface of the globe, so intricate, so inconceivably complex are the processes in Nature. In no way can we get such an overwhelming idea of the grandeur of Nature, as when we consider, that in accordance with the law of the conservation of energy, throughout the infinite, the forces are in a perfect balance, and hence the energy of a single thought may determine the motion of a Universe. It is not necessary that every individual, not even that every generation or many generations, should have the physical instrument of sight, in order to be able to form images and to think, that is, form ideas or conceptions; but sometime or other, during the process of evolution, the eye certainly must have existed, else thought, as we understand it, would be impossible; else conceptions, like spirit, intellect, mind, call it as you may, could not exist. It is conceivable, that in some other world, in some other beings, the eye is replaced by a different organ, equally or more perfect, but these beings cannot be men.

Now what prompts us all to voluntary motions and actions of any kind? Again the eye. If I am conscious of the motion, I must have an idea or conception, that is, an image, therefore the eye. If I am not precisely conscious of the motion, it is, because the images are vague or indistinct, being blurred by the superimposition of many. But when I perform the motion, does the impulse which prompts me to the action come from within or from without? The greatest physicists have not disdained to endeavor to answer this and similar questions and have at times abandoned themselves to the delights of pure and unrestrained thought. Such questions are generally considered not to belong to the realm of positive physical science, but will before long be annexed to its domain. Helmholtz has probably thought more on life than any modern scientist. Lord Kelvin expressed his belief that life’s process is electrical and that there is a force inherent to the organism and determining its motions. Just as much as I am convinced of any physical truth I am convinced that the motive impulse must come from the outside. For, consider the lowest organism we know — and there are probably many lower ones — an aggregation of a few cells only. If it is capable of voluntary motion it can perform an infinite number of motions, all definite and precise. But now a mechanism consisting of a finite number of parts and few at that, cannot perform are infinite number of definite motions, hence the impulses which govern its movements must come from the environment. So, the atom, the ulterior element of the Universe’s structure, is tossed about in space eternally, a play to external influences, like a boat in a troubled sea. Were it to stop its motion it would die. Matter at rest, if such a thing could exist, would be matter dead. Death of matter! Never has a sentence of deeper philosophical meaning been uttered. This is the way in which Prof. Dewar forcibly expresses it in the description of his admirable experiments, in which liquid oxygen is handled as one handles water, and air at ordinary pressure is made to condense and even to solidify by the intense cold. Experiments, which serve to illustrate, in his language, the last feeble manifestations of life, the last quiverings of matter about to die. But human eyes shall not witness such death. There is no death of matter, for throughout the infinite universe, all has to move, to vibrate, that is, to live.

I have made the preceding statements at the peril of treading upon metaphysical ground, in my desire to introduce the subject of this lecture in a manner not altogether uninteresting, I may hope, to an audience such as I have the honor to address. But now, then, returning to the subject, this divine organ of sight, this indispensable instrument for thought and all intellectual enjoyment, which lays open to us the marvels of this universe, through which we have acquired what knowledge we possess, and which prompts us to, and controls, all our physical and mental activity. By what is it affected? By light! What is light?

We have witnessed the great strides which have been made in all departments of science in recent years. So great have been the advances that we cannot refrain from asking ourselves, Is this all true, or is it but a dream? Centuries ago men have lived, have thought, discovered, invented, and have believed that they were soaring, while they were merely proceeding at a snail’s pace. So we too may be mistaken. But taking the truth of the observed events as one of the implied facts of science, we must rejoice in the immense progress already made and still more in the anticipation of what must come, judging from the possibilities opened up by modern research. There is, however, an advance which we have been witnessing, which must be particularly gratifying to every lover of progress. It is not a discovery, or an invention, or an achievement in any particular direction. It is an advance in all directions of scientific thought and experiment. I mean the generalization of the natural forces and phenomena, the looming up of a certain broad idea on the scientific horizon. It is this idea which has, however, long ago taken possession of the most advanced minds, to which I desire to call your attention, and which I intend to illustrate in a general way, in these experiments, as the first step in answering the question “What is light?” and to realize the modern meaning of this word.

It is beyond the scope of my lecture to dwell upon the subject of light in general, my object being merely to bring presently to your notice a certain class of light effects and a number of phenomena observed in pursuing the study of these effects. But to be consistent in my remarks it is necessary to state that, according to that idea, now, accepted by the majority of scientific men as a positive result of theoretical and experimental investigation, the various forms or manifestations of energy which were generally designated as “electric” or more precisely “electromagnetic” are energy manifestations of the same nature as those of radiant heat and light. Therefore the phenomena of light and heat and others besides these, may be called electrical phenomena. Thus electrical science has become the mother science of all and its study has become all important. The day when we shall know exactly what “electricity” is, will chronicle an event probably greater, more important than any other recorded in the history of the human race. The time will come when the comfort, the very existence, perhaps, of man will depend upon that wonderful agent. For our existence and comfort we require heat, light and mechanical power. How do we now get all these? We get them from fuel, we get them by consuming material. What will man do when the forests disappear, when the coal fields are exhausted? Only one thing according to our present knowledge will remain; that is, to transmit power at great distances. Men will go to the waterfalls, to the tides, which are the stores of an infinitesimal part of Nature’s immeasurable energy. There will they harness the energy and transmit the same to their settlements, to warm their homes by, to give them light, and to keep their obedient slaves, the machines, toiling. But how will they transmit this energy if not by electricity? Judge then, if the comfort, nay, the very existence, of man will not depend on electricity. I am aware that this view is not that of a practical engineer, but neither is it that of an illusionist, for it is certain, that power transmission, which at present is merely a stimulus to enterprise, will some day be a dire necessity.

It is more important for the student, who takes up the study of light phenomena, to make himself thoroughly acquainted with certain modern views, than to peruse entire books on the subject of light itself, as disconnected from these views. Were I therefore to make these demonstrations before students seeking information — and for the sake of the few of those who may be present, give me leave to so assume — it would be my principal endeavor to impress these views upon their minds in this series of experiments.

It might be sufficient for this purpose to perform a simple and well-known experiment. I might take a familiar appliance, a Leyden jar, charge it from a frictional machine, and then discharge it. In explaining to you its permanent state when charged, and its transitory condition when discharging, calling your attention to the forces which enter into play and to the various phenomena they produce, and pointing out the relation of the forces and phenomena, I might fully succeed in illustrating that modern idea. No doubt, to the thinker, this simple experiment would appeal as much as the most magnificent display. But this is to be an experimental demonstration, and one which should possess, besides instructive, also entertaining features and as such, a simple experiment, such as the one cited, would not go very far towards the attainment of the lecturer’s aim. I must therefore choose another way of illustrating, more spectacular certainly, but perhaps also more instructive. Instead of the frictional machine and Leyden jar, I shall avail myself in these experiments, of an induction coil of peculiar properties, which was described in detail by me in a lecture before the London Institution of Electrical Engineers, in Feb., 1892. This induction coil is capable of yielding currents of enormous potential differences, alternating with extreme rapidity. With this apparatus I shall endeavor to show you three distinct classes of effects, or phenomena, and it is my desire that each experiment, while serving for the purposes of illustration, should at the same time teach us some novel truth, or show us some novel aspect of this fascinating science. But before doing this, it seems proper and useful to dwell upon the apparatus employed, and method of obtaining the high potentials and high-frequency currents which are made use of in these experiments.


O svjetlu i drugim visoko-frekvencijskim pojavama

Nikola Tesla

Franklinov institut, Philadelphia, 24. veljače 1893.

Nacionlna udruga za električno svjetlo, St. Louis, 1. veljače 1893.


Kada promatramo svijet oko sebe, Prirodu, ushićeni smo njenom ljepotom i veličajnošću. Svaka promatrana stvar, pa i izčezavajuće mala, predstavlja svijet za sebe, tj. kao cijeli svemir, materija i sila upravljana zakonom, —svijet, čije
nas spoznavanje ispunja osjećajem čuđenja i neizostavno nas potiče na neprestano razmišljanje i potragu. Ali u tom golemom svijetu svih objekata koje nam odkrivaju naša čula, najčudesniji i najprivlačniji za naše misli je, nedvojbeno, visoko razvijen organizam, misleće biće. Ako postoji išta što nas zadivljuje u stvaralaštvu Prirode, to je svakako ova neshvatljiva struktura, koja obavlja bezbrojna gibanja podčinjena vanjskim utjecajima. Razumjevanje njenog ponašanja, bolji uvid u ovo djelo Prirode, uvjek je bio fascinantan cilj mislioca, a nakon mnogih stoljeća dubokih istraživanja čovjek je došao do podrobnog razumijevanja funkcija njegovih organa i osjetila. Ponovno, u posvemašnjem skladu svojih dijelova, dijelova koji čine ili dodiruju naše biće, oko je najčudesnije od svih organa i osjetila. Ono je nejvrjednije, najpotrebnije od svih spoznajnih ili pokrečućih organa, ono je veliki ulaz kroz koji znanje ulazi u naš um. Od svih organa, ono je jedino koje je najizravnije povezano s onim što zovemo intelektom. Ta je veza toliko čvrsta da se često kaže da se sama duša odkriva putem očiju.

Može se prihvatiti kao gotova činjenica, koja slijedi iz teorije djelovanja oka, da su za svaki vanjski podražaj, tj. za svaku sliku koja se stvara na retini, krajevi živčanih vlakana (koji moraju biti pod posebnom napetošću ili u stanju
vibracije) odgovorni za prijenos signala umu. Ne čini se nevjerojatnim da, kad se snagom uma priziva neka slika, onda se udaljeno refleksno djelovanje, bez obzira koliko slabo, obavlja na odgovarajućim krajevima vidnih živaca, a prema tome i na retini. Hoće li ikada biti u ljudskoj moći proučiti stanje retine, uznemirene misaonim ili refleksnim djelovanjem, s pomoću nekog optičkog ili drugog postupka, da bi se jasna predočba njenog stanja mogla dobiti u bilo kojem trenutku? Kad bi to bilo moguće, problem čitanja nečijih misli u svim pojedinostima, kao i čitanja slova otvorene knjige, mogao bi biti puno jednostavnije rješen, nego mnogi problemi u području pozitivne fizikalne znanosti, u rješenje kojeg mnogi znanstvenici, ako ne i većina, neizravno vjeruju. Helmholtz je pokazao da su temelji očiju sami svijetlostni, te je on bio u stanju vidjeti, u potpunom mraku, gibanje svojih ruku u svjetlucanju svojih vlastitih očiju. Ovo je jedan od najzačudnijih eksperimenata ostvarenih u povijesti znanosti, a vjerojatno ga samo par osoba može zadovoljavajuće ponoviti, jer je lako moguće da je svjetlucanje očiju povezano s neuobičajenom aktivnošću uma i velikom imaginativnom snagom. Kao da se radi se o fluorescenciji moždane aktivnosti.

Druga činjenica koja potvrđuje ovu priču, koju su vjerojatno mnogi primijetili, budući da se nalazi u popularnim pripovjestima, ali koje se ne mogu sjetiti da je zabilježena kao rezultat promatranja, je da povremeno, kada se neka ideja ili slika iznenada pojavi u našem umu, onda se pojavljuje različit i ponekad bolan osjećaj svjetlucanja u oku, primjetljiv čak i usred bijela dana. Izreka da se tada duša pojavljuje u oku je duboko utemeljena i čini se kao da izražava veliku istinu. Ona ima veliko značenje za onoga tko, kao pjesnik ili umjetnik, slijedeći samo urođeni nagon ili ljubav prema Prirodi, nalazi ushićenje u bezciljnim mislima te u samom promišljanju prirodnih fenomena,
ali ima još dublje značenje za onoga tko, u duhu pozitivnog znanstvenog istraživanja, teži odkrivanju uzroka i posljedica. U biti je fizičar onaj kojemu je oko predmet najvećeg divljenja.

Dvije činjenice o oku moraju nužno impresionirati duh fizičara, unatoč tome što može misliti ili reći da je to nesavršen optički instrument, zaboravljajući da je sam pojam savršenosti, ili mu se čini, bio usvojen posredstvom tog istog instrumenta. Najprije, oko je, barem prema našim sadašnjim znanjima, jedini organ koji je izravno pod utjecajem suptilne tvari koja, kako nas uči znanost, ispunja sav prostor; drugo, to je najosjetljiviji među našim organima, daleko osjetljiviji prema vanjskim podražajima nego ikoji drugi.

Slušni organ podrazumjeva utjecaj dohvatljiva tijela, organ njuha - prijenos odvojenih materijalnih čestica, a organ okusa - dodira ili sile, izravan kontakt ili barem neki međuutjecaj dohvatljive tvari, a vrijedi čak i u slučaju životinjskih organizama, u kojih su u nekim slučajevima ti organi razvijeni do čudesnog savršenstva. Budući da je tako, čini se začudnim da je jedino vidni organ sposoban biti potaknut onim što svi naši drugi organi nisu u stanju niti razabrati, a ipak igra bitnu ulogu svim prirodnim pojavama koje šalju svu energiju i održavaju gibanje, a najdelikatnije od svega, život, ali koje ima vlastitosti takve da čak i znanstveno upućen um ne može razlikovati život od svega onog što zovemo materijom. Uzimljući u obzir samo to, kao i činjenicu da nam oko svojom čudesnom snagom proširuje inače vrlo uzko područje vida daleko izvan granica malog svijeta u kojem se nalazimo, kako bismo obuhvatili milijarde drugih svjetova, sunaca i zvijezda u bezgraničnim dubinama svemira, trebalo bi opravdati tvrdnju da je to organ višega reda. Njegove mogućnosti su neshvatljive. Priroda, koliko nam je poznato, nikada nije stvorila nešto čudesnije. Jedva možemo imati slabašnu predočbu o njegovoj čudesnoj snazi razčlanjujući što sve čini i uspoređivanjem. Kada valovi etera nadraže ljudsko tijelo, oni izazivlju osjećaj topline ili hladnoće, ugode ili boli, ili možda druge osjećaje kojih nismo svjesni, ili svaki stupanj jakosti tih podražaja, kojih stupnjeva ima bezkonačno mnogo, pa prema tome i bezkonačno mnogo različitih podražaja. A naš osjećaj dodira, ili naš osjećaj sile, ne može nam odkriti te razlike u stupnju ili jakosti, osim ako su jako velike. Sada možemo lako shvatiti kako organizam kao što je ljudski, u vječnoj mijeni razvoja, ili govoreći filozofičnije, u prilagodbi Prirodi, omeđen uporabi jedino čula dodira ili sile, na primjer, može razviti taj osjećaj do takvog stupnja osjetljivosti ili savršenosti, da je u stanju razlikovati najsićušnije razlike u temperaturi čak i tijela na nekoj udaljenosti, do stotnike, tisućine, ili čak milijuntninke stupnja. Ipak, ovo naoko nemoguće ostvarenje ne bi se moglo usporediti s mogućnostima oka, koje je sposobno razlikovati i proslijediti umu u jednom jedinom trenutku bezbrojne osobitosti tijela, bilo kao oblik, ili boju, ili neku drugu. Ova snaga oka oslanja se na dvije stvari, naime, na pravocrtnom proslijeđivanju promjena kojima je podložna, te njegovoj osjetljivosti. Kazati da je oko osjetljivo ne znači da nismo ništa kazali. U usporedbi s njime, svi drugi organi su grozno nepouzdani. Organ njuha koji vodi psa na putu do jelena, organ dodira ili sile koji vodi bubu tijekom njenih lutanja, slušni organi na koji utječu najsitnije promjene u zraku, su doista osjetilni organi, ali što su oni u usporedbi s ljudskim okom! Nema sumnje, ono odgovara na najslabiji eko ili promjene u mediju; nedvojbeno, ono nam donosi vijesti s drugih svjetova, bezgranično daleke, ali jezikom koji nismo u stanju uvijek razumjeti. A zašto ne? Jer živimo u mediju ispunjenom zrakom i drugim plinovima, u parama u kojim lebdi gusta masa čvrstih čestica. One igraju važnu ulogu u mnogim fenomenima; one gube energiju titranja prije nego dospiju do oka; one su također nositelji razornih klica, ulaze u naša pluća i druge organie, začepljuju kanale i neprimjetno, ali neminovno, onemogućuju tijek života. Ako bismo se samo mogli riješiti sve zamislive materije u vidokrugu teleskopa, to bi nam odkrilo neslućena čudesa. Čak i nepripremljenim okom, mislim da bismo bili u stanju razlikovati čisti medij, sićušne objekte na razdaljinama mjerenim vjerojatno stotinama ili čak tisućama kilometara.

Ali ima još nešto u vezi oka što nas uzhićuje još više nego ove čudesne osobitosti koje smo primijetili, gledajući ga s motrišta fizičara, kao najobičniji optički instrument, - nešto što nas privlači više od začudne sposobnosti biti pod izravnim utjecajem titranja medija, bez utjecaja glavnine materije, a više nego njegova nevjerojatno osjetljivost i snage razlučivanja. Njegova se važnost ogleda u životnom procesu. Kakvi god bili naši pogledai na prirodu i život,
moramo biti zapanjeni kad, po prvi puta u svojim mislima, shvaćamo važnost oka u fizičkim procesima mentalnih ostvarenja ljudskog organizma. I kako može biti drukčije, kada shvaćamo da nam je upravo oko sredstvo s pomoću kojeg je ljudska rasa dobila cjelokupno znanje koje posjeduje, te da ono upravlja svim našim gibanjima i, štoviše, u svim našim djelovanjima.

Nema drugog načina stjecanja znanja nego okom. Što je temelj svih filozofskih sustava modernog vremena, zapravo sveukupne filozofije čovjeka? Postojim, dakle mislim; mislim, dakle postojim; postojim. Ali kako ću misliti i kako ću znati da postojim, ako nemam oka? Jer znanje uključuje svijest; svijet uključuje ideje, koncepte; koncepti uključuju crteže ili slike; a slike osjećaj vizije, pa prema tome i organ vida. Ali kako je sa slijepim osobama, bit ćete upitani. Da, slijepa osoba može opisati divne poeme, forme i prizore iz stvarnog života, iz svijeta kojega ne vidi. Slijepa osoba može dodirivati tipke instrumenta s nepogrešivom točnošću, može modelirati najbrži čamac, može odkriti i izumiti, računati i konstruirati, može učiniti i veća čuda - ali sve slijepe osobe koje su to ostvarile potječu od onih koji su videći. Priroda može dosegnuti iste rezultate na mnoge načine. Kao što val u  fizikalnom svijetu u beskonačnom oceanu medija koji ga cijelog prožima, tako i u svijetu organizama, u životu, početni poticaj se nastavlja, ponekad možda brzinom svjetlosti, a ponekad možda brzinom takvom da stoljećima i stoljećima čini se kao da stoji, prolazeći kroz procese posve neshvatljive čovjeku, ali u svim svojim oblicima i stanjima njegova energija je vječito prisutna. Jedna jedina zraka svjetlosti s udaljene zvijezde koja pada u oko tirana u pradavno vrijeme, mogla je promijeniti tijek njegova života, mogla je promijeniti sudbinu naroda, mogla je transformirati površinu zemlje, toliko su zakučasti i neshvatljivo složeni procesi u Prirodi. Nije moguće dobiti sveobuhvatnu predočbu veličajnosti Prirode kao kada smatramo da su, u skladu sa zakonom sačuvanja energije, tijekom beskraja, sve sile u posvemašnjoj ravnoteži, pa prema tome energija jedne jedine misli može odrediti gibanje Svemira. Nepotrebno je da svaka osoba, čak niti svaka generacija ili mnoge generacije, posjeduju fizički instrument vida kako bi bili u stanju stvarati slike i misliti, tj. stvarati zamisli ili koncepte; ali u nekom trenutku, tijekom procesa evolucije, oko je svakako trebalo postojati, inače misao kakvu poznajemo ne bi bila moguća; također i koncepti kao što su duh, intelekt, um, zovi ga kako hoćeš, ne bi mogli postojati. Moguće je da je u nekom drugom svijetu, u nekim drugim bićima, oko zamijenjeno drugim organom, jednakim ili savršenijim, ali takva bića ne mogu biti ljudi.

Što nas potiče na namjerne kretnje i djelovanja bilo koje vrste? Ponovno oko. Ako sam svjestan kretanja, moram imati zamisao ili koncepciju, tj. sliku, pa prema tome i oko. Ako nisam sasvim svjestan kretanja, ono je, radi toga što su
slike slabe ili nejasne, zasjenjeno međudjelovanjem mnogih kretnji. Ali kada izvodim gibanje, dolazi li poticaj za djelovanje iznutra ili izvana? Najveći fizičari nisu prezirali učiniti napor da odgovore na to i slična pitanja i
povremeno se prepustili užitcima čistog i nesputanog promišljanja. Za takva se pitanja općenito smatra da su izvan područja pozitivne fizikalne znanosti, ali će uskoro biti usvojena u njeno područje. Helmholtz vjerojatno posjeduje više zamisli o životu nego ikoji drugi suvremeni znanstvenik. Lord Kelvin je izrazio vjerovanje da su životni procesi električni i da u svakom organizmu postoji nutarnja sila koja određuje njegove pokrete. Kao što sam siguran u svaku
fizikalnu istinu, isto tako vjerujem da motivirajući podražaj mora doći izvana. Jer, promotrimo najniže organizme koje poznajemo - ima vjerojatno mnogo nižih vrsta - nakupina od samo par stanica. Ako je sposoban na proračunato gibanje, onda može izvesti beskonačno mnogo gibanja, svako od njih određeno i točno. Međutim mehanizam koji se sastoji od konačno mnogo dijelova ne može izvesti beskonačno mnogo određenih gibanja, prema tome impulsi koji upravljanju njegovim pokretima moraju potjecati iz okoliša. Prema tome atom, posljednji element strukture Svemira, vječito se giblje prostorom, igrom vanjskih utjecaja, kao čamac na uzburkanom moru. Ako bi zaustavio gibanje, umro bi. Materija u mirovanju, ako bi to moglo postojati, bila bi mrtva materija. Smrt materije! Nikada nije bila iskazana istina dubljeg filozofskog značnje. Upravo ga na taj način Prof. Dewar izražava u opisu svojih čudesnih eksperimenata, u kojim se tekućim kisikom upravlja slično kao što se upravlja vodom, a zrak pod normalnim tlakom se kondenzira i ukrućuje pod jakom hladnoćom. Pokusi koji služe da predoče (njegovim jezikom) najslabije kretnje materije blizu su umiranja. Ali ljudsko oko neće svjedočiti takvoj smrti. Nema smrti materije, jer duž beskonačnog svemira sve se giblje i titra, tj. živi. Predhodne sam tvrdnje formulirao riskirajući da ću odlutati u područje metafizike, sve u želji da uvedem predmet ovog predavanja tako da ne bude nezanimljiv, nadam se, slušateljstvu kojem imam čast obratiti se. Ali sada, vraćajući se temi, ovaj božanski organ vida, ovaj nuždan instrument za misao i
sva intelektualna zadovoljstva, koji nam otvara čuda ovog svemira, putem kojeg smo primili znanja koja posjedujemo, koji nas upozorava i upravlja svom našom misaonom aktivnošću - što na njega utječe? Svjetlost? Što je svjetlost?
Svjedočimo velikim koracima ostvarenim u svim područjima znanosti tijekom posljednjih godina. Ti koraci su tako veliki da se ne možemo suzdržati i upitati, je li sve to istina, ili je to samo san? Stoljećima ranije ljudi su živjeli, mislili, odkrivali, pronalazili, vjerujući da su se uzdizali, dok su zapravo samo napredovali puževim korakom. Ali uzevši u obzir istinu promotrenih događaja kao jednu od znanstvenih istina, mora nas veseliti golem napredak koji je već ostvaren, a još više izčekivanje onoga što tek treba doći, sudeći prema mogućnosti koje je otvorilo suvremeno istraživanje. Ne radi se o odkriću, ili pronalasku, ili dostignuću u nekom posebnom smjeru. Radi se o napredku u svim smjerovima znanstve misli i pokusa. Mislim na poopćenja prirodnih sila i pojava, naziranje neke široke misli na znanstvenom horizontu. A to je zamisao koja je međutim davno opsjedala mnoge najnaprednije umove, kojoj želim svratiti vašu pozornost i koju namjeravam ilustrirati vrlo općenito u ovim eksperimentima, kao prvi korak u odgovoru na pitanje "Što je svjetlost" i pojasniti suvremeno značenje te riječi.

Izvan je domašaja mojeg predavanja upuštati se u predmet svjetlosti općenito. Moj je cilj samo svratiti sada vašu pozornost na jednu vrstu svjetlosnih efekata i na studij tih efekata. Ali da bih bio u skladu s mojim primjetbama, treba reći da, prema toj ideji, sada prihvaćenoj od većine znanstvenika kao pozitivan rezultat teorijskih i eksperimentalnih istraživanja, različiti oblici i pojavnosti energije koje se obično označuju kao "električne" ili točnije “elektromagnetske", su pojavnosti iste naravi kao i izsijavanja topline i svjetlosti. Prema tome, fenomeni svjetlosti i topline i drugi, mogu se zvati električnim fenomenima. Na taj je način električna znanost postala majka svih znanosti i njezino proučavanje je postalo iznimno važno. Dan kada ćemo točno znati što je "elektricitet", bit će zabilježen kao događaj vjerojatno veći i važniji nego bilo koji drugi zabilježen u povijesti ljudske vrste. Doći će vrijeme kad će ugoda, pa možda i samo postojanje čovjeka ovisiti o ovom čudesnom sredstvu. Za naše postojanje i ugodu zahtijevamo toplinu, svjetlost i mehaničku snagu. Kako to sve dobivamo? Dobivamo ih iz goriva, potrošnjom materijala. Što će čovjek učiniti kada šume nestanu, kada se naslage ugljena izcrpe. Prema našem sadašnjem znanju, samo će jedna stvar preostati: prenositi snagu na velike udaljenosti. Čovjek će ići na vodopade, na plime, koje su izvori sićušnih dijelova beskonačne energije Prirode. Tamo će ukrotiti energiju i slati ju u svoja naselja, kako bismo ugrijali svoje domove, dobivali svjetlost i održavali svoje pokorne sluge - mašine, da rade. Ali kako će prenijeti tu energiju ako ne elektricitetom? Kako ne bi onda ugoda, samo postojanje čovjeka, ovisilo o elektricitetu? Svjestan sam da ovo stanovište ne potječe od praktičnog inženjera, ali niti od iluzionista, jer je sigurno da će prijenos snage, koja je danas samo poticaj proizvodnji, biti jednog dana strašna potreba.

Važnije je za studenta, koji se zanima za studij svjetlosnih fenomena, da se temeljito upozna sa suvremenim pogledima, nego da prođe cijele knjige o predmetu samog svjetla kao da je nepovezano s tim pogledima. Ako bih držao ove eksperimente pred studentima koji traže informacije - a radi par njih koji su možda nazočni, moj glavni napor bio bi da ovim nizom eksperimenata utisnem te poglede u njihove umove.

Moglo bi biti dovoljno za tu svrhu izvesti jednostavan i dobro poznat pokus. Mogu uzeti poznati aparat, Leydensku bocu, nabiti je s pomoću elektrostatičkog generatora i zatim ju izbiti. Objašnjavajući vam njezino stalno stanje kad je nabijena, i njezino prijelazno stanje tijekom izboja, svraćajući vašu pozornost na sile koje ulaze u igru i na razne fenomene koje one proizvode, mogao bih u potpunosti uspjeti u ilustriranju te moderne ideje. Nema sumnje, misliocu će se ovaj jednostavni eksperiment dopasti isto kao i najčudesnija izložba. Ali ovo bi trebao biti eksperimentalni prikaz, onaj koji osim instruktivne ima i zabavne osobitosti, i kao takav jednostavan eksperiment neće doprinjeti ispunjenju predavačeve namjere. Moram radi toga odabrati drugi način ilustriranja, svakako dojmljiviji, ali možda i poučniji. Umjesto elektrostatičkog generatora i Leydenske boce, upotrijebit ću u ovim pokusima indukcijski svitak neobičnih značajki, koji sam podrobno opisao tijekom predavanje pred Londonskim institutom inženjera elektrotehnike (London Insititution of Electrical Engineers), veljače 1892. Ovaj indukcijski svitak u stanju je proizvesti izmjenične struje enormne razlike potencijala, titrajuće ekstremnom brzinom. S tim aparatom nastojat ću vam pokazati tri vrste učinaka, ili fenomena, a moja je želja da nas svaki eksperiment, dok služi svrsi ilustriranja, istodobno pouči i nekoj novoj istini, ili nam pokaže neke nove aspekte te fascinantne znanosti. Ali prije toga, čini mi se prikladnim i korisnim zadržati se na upotrijebljenim spravama, kao i na načinu dobivanja visokih [razlika; D.Ž.] potencijala i visoko- frekvencijskih struja koje ćemo rabiti u ovim pokusima.

Nikola Tesla the founder of Radio Technology and of Wireless Communication

During his lecture in St. Louis, Nikola Tesla showed for the first time in history the fundamentals of Radio Technology and Wireless Communication. This is described in detail by Margareth Cheney in her monograph Tesla / Man Out of Time (published in 1981), in Chapter 6 entitled "Radio".

From that monograph, we learn that during his public lecture in St. Louis, Nikola Tesla had the assistant Henry Primm Broughton (1865-1959). Henry's son William Gundry Broughton (1902-1994), in his public lecture in 1970s, informed about experiments assisted by his father Henry, proving without any doubt that Tesla should be credited for the discovery of Radio Technology and Wireless communication. See Chapter 6 ("Radio") of the aforementioned monograph by Margaret Cheney.

Here, we quote the foolowing short passage from ther book:

On August 31, 1892, The Electrical Engineer reported the return to New York of Mr. Nikola Tesla, the distinguished electrician, on the steamship Augusta Victoria from Hamburg. After commenting on the death of Tesla's mother and his subsequent illness, the journal added: "His magnificent reception at the hands of European electricians has become, like his investigations and researches, part of electrical history; and the honors conferred on him were such as to make Americans very proud of one who has chosen this country as a home."

He moved scientific history forward again in the spring of 1893 when, addressing the Franklin Institute in Philadelphia and the National Electric Light Association at St. Louis, he described in detail the principles of radio broadcasting.

At St. Louis he made the first public demonstration ever of radio communication, although Marconi is generally credited with having achieved this feat in 1895. Tesla's twenty-eight-year-old assistant at the St. Louis lecture was H. P. Broughton, whose son, William G. Broughton, is licensee of the Schenectady Museum memorial amateur radio station W21R. At the station's dedication speech in 1976 William Broughton touched upon highlights of Tesla's historic demonstration at St. Louis - after a week's preparation - as personally told to him by his father.

"Eighty-three years ago, in St. Louis, the National Electric Light Association sponsored a public lecture on high-voltage high-frequency phenomena," said the younger Broughton.


... "The world-famous genius who invented, conducted, and explained this lecture demonstration," he concluded, "was Nikola Tesla."

Although the St. Louis demonstration was no "message sent 'round the world" as Tesla would doubtless of course have preferred it to be, he had nevertheless demonstrated all the fundamental principles of modern radio:

  1. an antenna or aerial wire;
  2. a ground connection;
  3. an aerial-ground circuit containing inductance and capacity;
  4. adjustable inductance and capacity (for tuning);
  5. sending and receiving sets tuned to resonance with each other; and
  6. electronic tube detectors.

A more detailed information about Tesla's discovery of Radio Technology and of Wireless Communication.

Margaret Cheney

... The Smithsonian Institution has never adequately credited Tesla for his invention of radio. They have tended to call Marconi the "father of radio," and they have tended to give Edison credit for Tesla's work in alternating current, although Edison didn't work in that area at all. ... Source (Excerpt from an interview).


Nikola Tesla and Croatians

Nikola Tesla and his schooling in Croatia

Nikola Tesla in the city of Zagreb in 1892

Many thanks to Mario Filipi for his information about Henry P. Broughton, Tesla's assistant in St. Louis.

Mario Filipi: Nikola Tesla Beneath the Cobwebs, 2023, 552 pp.

Croatia, its History, Culture and Science