Nikola Tesla and His Works

In this age of practical endeavor, when everything is turned to its immediate use with the least delay possible, a life like that of Tesla, devoted to scientific research for the love of it, stands out in peculiar and interesting prominence. Such a character, however, is the natural outcome of the rapid advance in all material investigation, which has become so broad, and goes into so many different fields of research, that few workers attain to general prominence.

The last decade pays tribute to two names that have added something to our knowledge and better comprehension of nature's methods. These names are Hertz and Tesla. Hertz gave promise of showing the ultimate law that connects matter separated by space. The work so well begun was ended by his untimely death. Maxwell had shown that all of nature's reacting forces can be expressed by methods of mathematical analysis, and clearly formulated by the terms of an equation. By purely empirical methods Hertz gave physical proof of the truth of Maxwell's theoretical deductions, and so connected pure theory to practical fact.

Out of both pure theory and physical research came the general conclusion, that all manifestations of energy are but the different tangible or apparent evidences of one and the same force; that all energy, whatever its form of manifestation, is simply molecular agitation of greater or less degree. If that be true, then heat and light are merely the results of molecular agitation, and could this agitation be set up by purely mechanical means, heat or light would result. 

Tesla conceived the bold idea that, by causing matter to pass to the stage of luminous vibration, without remaining for any appreciable time in the stage of heat vibration, it would produce light without heat; and so near has he come to the practical accomplishment of this conception that he has set the scientific minds of all Europe thinking, and placed his name beside that of Hertz.

Tesla comes from Herzegovina, near the Western borderland of Turkey, and in early youth was a pupil of the government schools where he lived. Later, he held government office as a collector of statistics. His twenty-third year found him in Paris, whither he had come to study engineering at the École Polytechnique. From this school he went to the Edison Station Paris as an engineer, where his ability was quickly recognized, and he was soon persuaded to come to this country. Here a place was found for him in the celebrated Edison laboratory. He remained in this position a few years, but, having many ideas that he wished to develop independently, he left that employ, and has since conducted a laboratory of his own in New York City, which has been devoted purely to physical research and scientific investigation. 

Thirteen years' residence in this country has not deprived Tesla of his cosmopolitan character and disposition. Master of five or six languages and a devotee to broad science, he is truly a citizen of the world, a genial host and charming companion. What first brought him into prominence and gave him the means to go further, was his discovery of the "Rotary Field Motor," an invention of marked originality and beauty, but not appreciated at its full value at the time of its discovery. Announced by him and commercially disposed of in 1888, it is now just coming into general use. Simple and beautiful as it seemed, our knowledge of electrical engineering was not then equal to the task of making the machine electrically right. European engineers, however, held to the work, and, following in their footsteps, we now understand the rotary field motor, and the largest electrical enterprise in the world, the fifty thousand horse-power plant for sending the power of Niagara to light Buffalo and other distant towns, will use the multiphase system that Tesla first gave to the engineering world six years ago.

An apt illustration of the difference between the purely theoretical or scientific mind, and the semi-practical mind guided by scientific training, suggests itself here. Professor Ferraris, of Turin, independently discovered and announced the principle and operation of the rotary field motor at about the time that Tesla did the same thing in this country. The professor's announcement was in the form of a paper to a scientific society. Tesla made many forms of the machine, reduced his theory to a practical operative device, and, having protected his invention by many patents, he exhibited his machines to the American Institute of Electrical Engineers in May, 1888. Professor Ferraris's description, however, antedates Tesla's exhibition by some months. It is worthy of remark in passing, that three of the epoch making inventions in electrical advance are of Italian origin. I refer to the chemical element, or Volta's pile; the first direct current generator invented by Pacinotti, and left in obscurity for years; and last, but greatest of all for the coming era of long distance power transmission, the rotary field engine of Ferraris and Tesla. 83 

Before considering Tesla's more recent work, it seems appropriate to describe briefly the salient features of this machine, which can be best done by comparing it with the ordinary type of electric motor. This, in general terms, is an engine having a fixed and a revolving part, of which the latter, turning about its spindle, communicates motion to other machinery. The moving part is always provided with commutating devices that constantly shift the magnetic axis backward, in the same measure and degree that the moving part turns forward. These devices are always intricate and complex. They are, in fact, the weak point of all electric engines. The Tesla rotary field machine, being entirely free from them, is a marvel of simplicity and ingenuity. To understand this machine, one must picture a circular iron ring, and conceive it to be magnetized along a vertical diameter, North Pole at the top; then, a moment later, along a horizontal diameter, with the North Pole at the right; again along the vertical diameter, but North Pole at the bottom; and lastly on the horizontal line again, with North Pole at the left, thus completing a revolution of the North Pole around the ring. Such an effect is called a rotating magnetic field, and can be perfectly produced by the simultaneous use of two independent alternating currents, which follow each other periodically in such a way that one has always a maximum value or strength when the other is zero, and conversely. If now the iron ring is wound all around with a coil of wire closed on itself, and one such current be introduced to this winding at the extremities of a vertical diameter, while another is simultaneously introduced to the same winding at the extremities of a horizontal diameter, they will jointly produce a revolving magnetic field that turns continuously around the ring, while the latter remains fixed in space. We then have a fixed magnet, but the magnetism itself, or magnetic axis, is in motion. A compass or magnetic needle suspended freely inside the ring would spin around in its endeavor to follow the revolving magnetism or the shifting magnetic axis of the ring.

Tesla delights in surprises for the public. He generally brings a new line of development to fair completion before giving it any public exhibition. The rotary field motor was a genuine surprise to the world of electrical engineering in 1888. Nothing more was heard from him for two years, and his motor-talked of awhile as a sort of nine days' wonder-was practically forgotten, while he was at work on other problems, of which no hint was given until his celebrated lecture at Columbia College, in the spring of 1890. In this lecture he exhibited for the first time his wonderful "high frequency effects," and certainly gave the scientific world some promise of obtaining light without heat, although this accomplishment was far from fruition at the time, and I believe is now abandoned as hopeless on the lines attempted. Still, his researches developed many new and surprising effects, which, aside from their purely laboratory interest, may have a certain commercial value. In these researches, which constitute an investigation of what have now come to be known as "The Tesla Effects," it was his aim and purpose to establish by experimental process the identity of light and some form of electrical manifestation of energy, and he gave to science much evidence of the electromagnetic theory of light that was new, though the theory, of course, had preceded his work, having been enunciated by Maxwell from purely theoretical deductions, and proven by Hertz by empirical methods.

Mr. Tesla started with the idea of setting matter into vibration at a rate approximating that of light (some two and a half millions a second), with the expectation that under such violent molecular agitation wou emit light. He has not as yet succeeded in obtaining so high a rate, but a much lower one produced some very surprising luminous effects. The general plan at first was this: To construct an alternating current dynamo that would produce this high rate of current alternation or pulsation. This current, now known as the "high frequency" current, will cause luminous effects in different media. Thus, in a darkened room, a bare copper wire conveying such a current will be seen to glow, and vacuum tubes will shine brightly, as a result of a molecular bombardment or agitation of the ether atoms, when such a current is sent through them under very high pressure the very high electro-motive force of several hundred thousands of volts being used in most of his experiments of this character. The dynamo method for getting very high frequencies was soon abandoned as inadequate, and the oscillatory discharge of a Leyden jar or plate condensers was substituted. This answered much better, although the frequency was then an unknown quantity and quite beyond control; and this departure led to the discovery of some very beautiful electro-static effects, which are still being pushed by many investigators with the hope of arriving at some result of commercial value.

As soon as news of Tesla's first lecture, and the experiments there shown, reached the other side of the Atlantic, he was at once invited by various scientific societies of Europe to deliver his lecture and perform his experiments before them. This he soon did; and the scientific minds of Europe were quickly at work investigating the so-called Tesla effects, the result being that the electro-magnetic theory of light may be regarded as proven, while it seems equally well-established that light without heat is not to be looked for as an outcome of the Tesla effects. A beautiful and startling exhibition of what can be done with electric energy, under properly arranged conditions, is that of causing vacuum tubes or partially exhausted bulbs to glow by merely holding them between two metallic plates (about four feet square, and two or three yards apart), which are made the terminal poles of a circuit conveying a high frequency and high voltage current. It was hoped that rooms could be lighted in this way by placing the plates in the walls, where such tubes would glow without any material connection whatever with the source of energy. 

Mr. Tesla claims that all electric and magnetic effects are traceable to the action of electro-static molecular forces, and in confirmation of this theory he produces what appears to be a veritable flame by the action of electro-statically charged molecules of gas. A flame is actually shown issuing from the tip of a wand, or from the ends of his fingers, which flame is devoid of heat, and by it no material is consumed. Perhaps the most surprising of the new facts elicited from his investigations is that the shock due to these very high voltage and high frequency currents can be supported by a person without any serious inconvenience. He passes a current of two hundred thousand volts through his body with perfect impunity, whereas one of two thousand volts will produce almost certain death from even a momentary shock. In one experiment, two wires are stretched parallel to each other across the room. When given the high tension current they emit streams of light, or brush discharges so profusely that light enough is produced to distinguish objects in the room. If the wires are bent into concentric hoops, one inside the other in the same plane, the annular space between them is filled with streamers that make a sheet of flame a yard or more in area.

Mr. Tesla is viewed by some as an impractical inventor-a mere visionary enthusiast-but this is hardly fair to one who has built up an entirely novel method for the experimental investigation of physical phenomena. This method, with its vast array of beautiful experiments, is original, and goes some steps beyond any point reached by previous work in the same line. There seems to be little of practical value in it for the electrical engineer. So we may say, that to the physicist Mr. Tesla stands as the pioneer of a new and wide field of research, while before the practical man of electricity he stands as the inventor of the "rotary field machine," a beautiful and unique conception, which he soon left for the practical man to figure out. 

Before the general public he stands as a phenomenal inventor from the Eastern World, from whom is expected little less than if he carried Aladdin's lamp in his hand. This view of the matter, of course, is wrong, and is an injustice both to the public and the inventor. Mr. Tesla is a hard and patient worker, and did enough for one decade in producing the rotary motor. He has doubtless much yet in store for us, but the difference should never be lost sight of between the work of the empirical physicist searching for nature's truths, and the reduction of a single result to a form for commercial use.