Nikola Tesla and His Work (1894)

Mr. Nikola Tesla has been prominent in the electrical held for more than ten years, and the creations that have sprung from his brain have made his name familiar to the general public. His work, however, has been of such an advanced order of electrical application that comparatively few have a clear idea as to just what he has accomplished.

Within the past three months a book has been published which tells the story and which is indeed a rather exceptional contribution to the electrical literature of the day, presenting, as it does, an elaborate description of all that Mr. Tesla has thus far given to the public in his patents and lectures.* It includes not only descriptions of his numerous inventions, but his personal writings upon the lines of thought and experiment he has advanced, and so affords the opportunity for a brief review of what he has done.

From both a literary and typographical standpoint the book is an excellent addition to the electrical library. It is tastily gotten up, and evinces care and literary skill in the editing; the illustrations, which are profuse, are good, and this is equally true of the frontispiece portrait of Mr. Tesla, which to many will largely enhance the value of the book.

With the exception of a short biographical sketch, Part I., comprising twenty-four chapters, is devoted to a rather exhaustive treatment of the many forms of rotary field motors that Mr. Tesla has from time to time invented. One of these chapters, which will meet the requirement of the average reader, is an abridgment of Mr. Tesla’s well remembered lecture before the American Institute of Electrical Engineers in May, 1888, in which he gave for the first time the rotary field motor invention to the public. Most of the remaining chapters of part I. are detailed descriptions of different modifications of the general multiphased motor system, such as would likely occur to an active inventor anxious to bar with a profusion of patents every access to a broad system naturally open to many variations. In fact, many of these chapters are little else than mere transcripts from patent specifications.

Part II. is devoted to high frequency phenomena, a field of investigation that seems to be peculiarly Mr. Tesla’s own. It opens with an interesting chapter that seems to be from the editor’s pen, in which he gives his own resume and estimate of the matter set forth in Mr. Tesla’s three lectures upon high frequency effects, lectures given in succession before the American Institute of Electrical Engineers, the Royal Institution in London, and the Franklin Institute in Philadelphia. These three lectures, reproduced verbatim and making as many long chapters, constitute, in fact, the main part of the work.

Part III., comprising seven short chapters, describes quite a variety of inventions of relatively minor importance, so far as Mr. Tesla’s work is generally known, and which would probably never have seen publication beyond the patent specifications, from which they are evidently drawn, had not the exhaustive design of this book rendered their inclusion excusable. The inventions here mentioned include an arc lighting system of earlier days, some suggestions of how a unipolar machine might be built, a pyromagnetic generator, a thermomagnetic motor, an anti-sparking dynamo brush, and a method of regulation for constant current. These chapters are interesting mainly as showing how much a professed inventor must do that is not in the line of great achievement.

A short but interesting chapter describing Mr. Tesla’s personal exhibit of apparatus at the World’s Fair, and a brief reference to his latest surprise, the “electro-magnetic oscillator” for producing high frequency currents by mechanical means, ends the volume.

With the exception of a few chapters by the editor, the volume is a collection of Mr. Tesla’s writings, and those who have followed his work closely will find in it little that is new. Much of the subject matter in Part I., devoted to polyphased currents, is taken in a sweeping manner from patent specifications, and as such will be new to some who little know, without such a review, how thoroughly Mr. Tesla looked after the possible variations of his broad invention. The various motors described are shown in their most elementary forms by mere diagrams of the operative circuits.

While these numerous variations of the same general idea are instructive as showing the growth of the invention in the inventor’s mind, and the gradual development of the mere abstract idea to different practical forms, still, in all these descriptions there is little to be found that has any practical bearing or importance to-day. The engineer will find in these chapters little that he cares to remember for practical use or application, the advocate of controversy as to priority of invention will find ample data for reference, and the student of electrical science will find in them evidence of how little the most thoughtful inventor can foresee the features of his invention that will lead to most controversy and discussion, for nowhere in these earlier writings is any importance attached to the frequency of the alternating current used. Throughout the twenty-four chapters of Part I. the charming delusion prevails by inference that all these machines are as good at one frequency as at another. One might also draw the erroneous conclusion that polyphased currents were first discovered and used by Mr. Tesla; on the other hand, no one can doubt that the biphased and triphased rotary field machines were simultaneously worked out by him as early as 1887. He did not leave the triphased machine for a follower to invent.

Following the general treatment of multiphased machines come descriptions of various devices and makeshifts (no word seems more appropriate) for working these machines by a single alternating current. The rotary field motor operated by multiphased currents, as its every feature indicates it should be, is a unique and characteristic thing and should have been left to the field of operation that its inherent simplicity must sooner or later create for it. Its birth, however, was contemporaneous with that of single alternating current working, so the genius that first showed the rotary field machine in practice must pervert his invention to meet the requirements of a system to which it was entirely unsuited. The description of these many attempts adds but little to the value of the book.

In chapter XIV. is given a description of a single alternating current motor that does not depend upon the production of two currents from one, and another chapter shows a similar motor with a condenser in circuit, which points to Mr. Tesla as one of the earliest users of this device.

One cannot resist the conclusion, however, that this part of the work is a little padded with the only ostensible purpose of showing what a lot of inventions Mr. Tesla has made, and the reader is tempted to wish he had not invented so much.

In Part II., devoted to high frequency effects, we have to consider an entirely different order of work, which may be properly classed as pure science, for there is scarcely a practical effect described in the many pages given to the three lectures.

In this work the purpose in view has apparently been to establish by experimental process the identical character of light and some form of electrical manifestation of energy. In attempting this proof, Mr. Tesla has doubtless given new evidence in favor of the electro-magnetic theory of light, which theory, of course, preceded his work.

In his endeavor to obtain a very high frequency, Mr. Tesla doubtless started with the notion of setting matter into vibration at a rate approximating that of light, with the expectation that under such violent molecular agitation it would emit light. It is left to be inferred that so high a frequency is scarcely possible of attainment, while a much lower one under favorable conditions produces the desired effects. The investigation of these conditions constitutes a large part of the three lectures, which are sometimes tedious with exhaustive detail; though doubtless essential to a thorough investigation of the problem and invaluable as a guide to further work, these minutiae are not always interesting reading. This fact seems to be appreciated occasionally, and when it is we find a digression in the form of some purely speculative possibility - generally a suggested practical application of the effect under consideration. These are often so purely speculative in character as to be actually amusing.

Seriously speaking, the scientific world to-day believes in the electro-magnetic theory of light which grows out of fundamental views enunciated by Faraday and elaborated in later years chiefly by Maxwell and Hertz. Mr. Tesla has not touched the mathematical side of this question, and so has added nothing to Maxwell’s proof. Hertz established by experimental or physical demonstration the truth of Maxwell’s deductions. So, if Mr. Tesla has added something to our scientific knowledge of this subject, it will consist in what he has added to the work of Hertz.

Broadly speaking, however, the Tesla experiments are the same in general results as those performed by Hertz, but are undertaken in a different and entirely original manner and are shown in far greater profusion and variety of effect. Indeed, Tesla’s investigation of the electrostatic field, so far as variety of effect is concerned, would seem to leave but little to be desired. Tesla’s labor in this direction was simply a long and painstaking investigation, the apparent purpose of which was really to determine what practical use, if any, can electrical science derive from the so-called Hertzian oscillations. If this question must be definitely answered by the Tesla experiments, we are compelled to say that no practical use for such phenomena has yet been shown.

The vacuum tube and light effects produced by rapid alternations of an electro-magnetic or electrostatic field, and the transmission of energy along a single wire without a return lead, are beautiful, and mostly novel exhibitions of what can be done with electric energy under properly arranged conditions, but they are not of practical value in any use that has yet been made of them. They are simply advanced laboratory experiments of great scientific beauty and interest.

The introductory part of one lecture is given to a description of the apparatus used for producing the high frequency effects, and the precautions that must be taken in the arrangement of the parts are carefully pointed out with a view to help the experimenter who desires to follow this line of investigation.

Another is opened with a description of the best form of generator to be used, preference being given to a form of motor dynamo for transforming direct current into an alternating current of low voltage by a simple dynamo conversion. This low voltage alternating current is then changed to high tension by an ordinary converter, and this current, on being passed through the oscillatory transformer, has its frequency raised to something like a million a second.

Introducing another lecture, Mr. Tesla goes into a long digression upon the human eye that deals in nothing but generalities, having little or no bearing upon the subject.

The effects described in these three papers may be classed, for sake of arrangement, as phenomena produced by electrostatic force, dynamic electricity phenomena, and vacuum tube effects. We will consider some of these briefly.

Mr. Tesla claims that all electric and magnetic effects can be traced to the action of electrostatic molecular forces. In fact, he goes much further in one of his speculative digressions and refers everything among Nature’s fanciful designs to the action of electrostatic force. His first claim finds some confirmation in a beautiful experiment he describes, in which he produces a veritable flame by the action of electrostatically charged molecules. A flame is thus produced by which, however, no material is consumed. He thinks this experiment gives us a further insight into the nature of an ordinary flame, which he attributes to the electrostatic effects produced by the chemical changes going on.

The experiments in which vacuum tubes are shown glowing brightly by simply being placed in a rapidly alternating electrostatic field are beautiful, but the practical application suggested - of lighting an apartment by simply creating an electrostatic field in the space between the walls and using detached vacuum tubes for lamps that will always be aglow when between the walls - is far from realization, and the reading public should not be left with the impression that anything of the sort has ever been accomplished.

Another very interesting experiment consists in the operation of lamps and motor devices by the discharge from condensers, and he points out methods of transforming or changing the voltage of direct as well as alternating currents by means of condensers, and expresses the hope in this connection of perfecting apparatus by which electricity of high tension may be obtained directly from heat energy itself. No suggestion is, however, given as to what the method is or how the transformation is to be effected. This hazy suggestiveness of great practical ends just in view but never reached becomes at times somewhat unsatisfactory.

Among the most beautiful of this array of experiments is one that illustrates the impedance of a rod or bar of practically no resistance when connected in a circuit to which a very high electromotive force and frequency is applied. Owing to the impedance the current may be shunted around it through a circuit of comparatively high resistance supplied with incandescent lamps that glow brilliantly when their terminals are connected to the bar at points only a few inches apart. It is further shown in this experiment that there are points or nodes on the bar, from which no current can be taken in the manner described, while others differently situated give a high difference of potential, and so marked is this distribution that the points can be readily selected by an ordinary voltmeter or by the lamp circuit itself.

The most surprising of the new facts elicited from these investigations is that the shock due to these very high potential and high frequency discharges can be supported by the person without serious inconvenience. This Mr. Tesla attributes to the fact that the body offers a large cross-section to the high frequency current, which distributes itself uniformly, so that the current density is small at any point of the path. The inference also follows that these currents pass through the human body in much the same manner as a direct current passes through a good conductor. The E. M. F. used in this experiment was about 2 X 10⁵ volts and the frequency near a million a second. With this enormous potential literally in hand Tesla grasps one pole of the high tension transformer and approaches the other to the opposite pole, on nearing which a brush discharge having the appearance of a flame passes from his hand to the free pole. Enlarging upon this phenomenon in his usual style he estimates that with a frequency of four million and an E. M. F. of 3 X 10⁶, his entire person would be enveloped in such a flame, but without danger.

In another beautiful experiment two straight wires are connected to the poles of the high tension transformer and stretched parallel to each other across the room, there being no cross connection between of any kind. When given the high tension current, these wires emit streams of light or brush discharges so profusely that light enough is produced to distinguish objects in the room. If these wires arc bent into concentric circles, one inside the other in the same plane, the annular space between them is filled with streamers that make a sheet of light about a metre in area.

Perhaps the most interesting feature of these high frequency phenomena is their apparent capability of operating various sorts of electric devices - even motors of a certain description - and this with only a single wire leading to the source of energy. In one of these illustrations Mr. Tesla is led to say that he thinks it probable these experiments indicate the possibility of operating a motor at any point of the earth’s surface from a central source with only an earth connection to the latter. This he hopes to accomplish by causing the electrical charge of the earth to oscillate and by the use of resonance a distant motor is made capable of picking out the current of different rate or frequency that is intended for its consumption or supply. It is probably suggestions of this character that have caused some readers to view Mr. Tesla’s work as that of a visionary enthusiast.

It is more important, however, to determine just what Tesla has given in this discussion of high frequency phenomena that is of value - for its value is really quite independent of any views he may hold concerning the possible future applications of electricity.

He has built up a method of experimental investigation of physical phenomena, concerning which much remains to be learned. This method, with its vast array of beautiful experiment, is original and goes some steps beyond the point reached by previous work in this field, which may be defined as the experimental investigation of molecular physics. In all this there is little of practical interest to the electrical engineer. In going into this domain Mr. Tesla left what is commonly called electrical engineering behind and his work in this new field should therefore not be judged by its standards.

To the physicist Mr. Tesla stands a pioneer of a new and wide field of research.

To the electrical engineer he stands the inventor of the rotary field machine, a brilliant and unique conception, which he soon left for the engineer to elaborate and figure out.

Before the general public he stands a phenomenal inventor from the Eastern World, from whom is expected little less than if he carried Aladdin’s lamp in his hand, which, of course, is wrong, and an injustice both to the public and to Mr. Tesla.

Mr. Tesla is a hard and patient worker and has done enough for one decade in producing the rotary motor. He has doubtless much of importance in store for us, but the difference should never be lost sight of between the search for Nature’s truths in the laboratory of the physicist and the reduction of the results attained, however great their promise, to a form suitable for commercial use.

* “Inventions, Researches and Writings of Nikola Tesla.” Edited by Thomas Commerford Martin, New York, 1894. Price, $4.00.