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Nikola Tesla — Guided Weapons & Computer Technology
Tesla Presents series, Part 3

Nikola Tesla; commentary by Leland I. Anderson
xiii, 238 pages,
18 photos, 8 line-art illustrations, indexed
ISBN: 0-9636012-9-6 (paperback), ISBN: 0-9636012-5-3 (hardcover)
337-NTGW ... $18.95 (paperback)
337H-NTGW ... $31.95 (hardcover)


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The third of four remarkable books in which Nikola Tesla presents, in his own words, through heretofore unpublished extended interview, lecture, legal deposition and proposal discourse, his accomplishments in the fields of high frequency alternating current power systems engineering, telecommunications, X-ray/material-stream emanations, and telemechanics.

A firsthand account of original experimental work given in a 1902 U.S. Patent Office Interference on "individualization" techniques for secure wireless communications, defining the fundamental AND logic gate—an essential component of present day digital computers.

This book, the third installment of the Tesla Presents series, is based upon legal records associated with the Nikola Tesla vs. Reginald A. Fessenden Patent Interference on the Fundamental AND-Gate logic circuit.  While the U.S. Patent Office record is sufficiently important on the basis of its title alone, Tesla winning the claim to this invention, surprisingly the deposition contains heretofore unpublished disclosures by Tesla on the operation of his large high frequency oscillators at both the Houston Street laboratory in New York and the Experimental Station in Colorado.  Information is presented on what Tesla spoke of as the "art of individualization" for obtaining various levels of security in wireless transmissions. Also included is material on the history of radio-controlled devices, the first practical form of these being Tesla's radio-controlled "telautomaton"an operational boat first demonstrated to the public at Madison Square Garden in 1898.

The setting was the mid 1890s, in Nikola Tesla's laboratory on South Fifth Avenue in New York City. His work was focused on the construction of independent remote-controlled devices he referred to as "telautomatons
. Experiments were conducted with tuned receiving instruments that would respond to electrical oscillations carried in a loop of heavy wire suspended from the laboratory's ceiling.

Then tragedy struck when on March 13, 1895 Tesla's workshop burned to the ground, along with all of its contents.  His reputation as an important inventor already established, the lab's destruction was viewed by many as a great calamity, a misfortune to the entire world. In spite of this setback, and driven by the enormous possibilities already suggested by his investigations, Tesla lost no time in establishing another laboratory.  His ongoing work led to the development of methods for selectively exciting any of several wireless receivers—the art of individualization—but being severely restricted by local conditions, in June 1899 Tesla established an experimental station at Colorado Springs where he continued his studies.  By the end of the year he had demonstrated to himself the practicality of his ideas. Realizing the importance of his ground-breaking techniques he gave instructions upon his return to New York that patent applications be prepared and submitted.  During the review period, the Patent Office notified Tesla that another patent application for a similar concept had been received from Reginald Fessenden and the office was directing an Interference investigation to determine priority. Depositions were taken in 1902.

In this, the third book of the Tesla Presents Series, engineer-historian Leland Anderson provides the transcript of the 1902 U.S. Patent Interference investigation concerning Tesla's System of Signaling.  The document, "Nikola Tesla vs. Reginald A. Fessenden," which is no longer on file at the U.S. Patent Office, contains Tesla's own depositions as well as those of his closest and most trusted associates, George Scherff and Fritz Lowenstein.  In addition to describing Tesla's "individualization" techniques for obtaining secure noninterferable radio communications—the patent is today recognized as the fundamental AND logic gate, a critical element of every digital computer—the interference record reveals that essential features of the spread-spectrum techniques of frequency-hopping and frequency-division multiplexing have their roots in the resulting patents.  Furthermore, there are new disclosures by Tesla on the operation of his large high voltage resonators at both the Houston Street laboratory and the Colorado experimental station.

Rarely in the history of science do we encounter such opportunities to gain deep insight into the fundamental ideas and concepts of an esteemed scientist/inventor. Only in recent years have we been able to truly understand the significance of Tesla's legacy to the electrical sciences.  Between 1888 and 1899 Tesla delivered nine historic demonstration lectures presenting to audiences the fundamental aspects of his scientific endeavors. His brilliant technical displays held packed lecture halls spellbound, arousing thunderous ovations and bringing accolades from top scientists of the day. In this way Tesla opened the minds of many to new and profound ideas and concepts. After the turn of the century Tesla was forced to restrict his lecturing—a great loss—because his inventions were being pirated.  As a result, we have very few direct records of his work after 1899.  No motion pictures or audio recordings of Tesla's early demonstration lectures exist, but the Tesla Presents series carries readers near to recapturing the experience.  Tesla's own words bring the story of his pioneering experiments to life.

In his laboratory on South Fifth Avenue (now West Broadway) in New York City, Tesla began work in the 1890s on the construction of remote-controlled devices, or "telautomatons," as he referred to them.  This work evolved from his investigations in 1893 of automatic mechanisms actuated from a distance.  Tesla performed experiments with tuned devices (secondary-actuated) that would respond by induction to an oscillator primary coil running up and around the cove in the experimental area of the laboratory.

Tragedy struck March 13, 1895, when the laboratory was burned to the ground.  Charles Dana, editor, the New York Sun, remarked in its columns:

The destruction of Nikola Tesla's workshop, with its wonderful contents, is something more than a private calamity.  It is a misfortune to the whole world.  It is not in any degree an exaggeration to say that the men living at this time who are more important to the human race than this young gentleman can be counted on the fingers of one hand; perhaps on the thumb of one hand.

Driven by the enormous possibilities his investigations suggested, Tesla lost no time in establishing another laboratory on East Houston Street.  He was now able to have tuned devices respond CONJOINTLY by induction from the coil around the experimental area.  A very interesting prospect indeed!  The question remained, could this condition also be achieved by radio? . . .

Tesla vigorously addressed the problem as an extension of the experiments performed in his New York City laboratories.  He successfully operated a wireless receiver using the conjoint transmission of signals at different frequencies June 27, 1899, as recorded in his notes.  So important did he consider the individualization concept and technique that following his return to New York City in January (1900) he instructed Scherff, his secretary and useful man, as a first order of business, to prepare patent applications from the notes kept in Colorado Springs.

The patent application was submitted, but during the period awaiting review, Tesla received notification from the U.S. Patent Office that another patent had been received from Reginald Fessenden on a similar concept and that the office was directing an Interference investigation to determine priority.  Depositions were taken in 1902, and the following section is a transcript of those depositions.

In addition to resolving the issue of Tesla's patent application having priority over that of Fessenden, the depositions are of interest today because they disclose not only unavailable information about the development of the invention but as well heretofore unavailable information about experiments performed at Tesla's laboratory in New York City and his experimental station at Colorado Springs.

A discussion and analysis of these disclosures is presented in the section immediately following the Interference transcript:

Nikola Tesla
New York, August 5, 1902
Before the Commissioner of Patents in the matter of an interference between the application of Nikola Tesla, filed July 16, 1900, Serial Number 23,847, for, Systems of Signaling, and an application of Reginald A. Fessenden, filed June 2, 1900, Serial Number 18,878, for Improvement in the Transmission and Receipt of Signals, Interference No. 21,701. . . .

NIKOLA TESLA, a witness called on his own behalf, having been first duly sworn and says, in answer to interrogatories proposed by counsel, as follows:

1 Q. Please state your name, age, occupation, and residence.
   A. Nikola Tesla; Waldorf-Astoria, New York City; place of occupation, Wardenclyffe, Long Island; age, 44; occupation, electrician.

2 Q. You are one of the contestants of this interference?
   A. Yes.

3 Q. Have you read the applications of Reginald A. Fessenden involved in this interference, and do you understand the same?
   A. I have, and understand the same.

4 Q. Have you read the stated issues of the interference as contained in the Patent Office notices, and do you understand the subject matter which is in dispute?
   A. I have read and understand them.

5 Q. Will you give a general history of your work in connection with methods and appliances pertaining to the general subject matters of this interference?
   A. As nearly as I recollect, I entered the study of electrical oscillations and apparata for producing the same some time in 1889.  I saw great possibilities and concentrated my efforts on producing efficient apparata and devising methods for various purposes.  I think I gave the first demonstration with tuned circuits before the American Institute of Electrical Engineers in 1891.  This work I followed up, and subsequently I presented novel and advanced results before scientific societies abroad in 1892.  My experiments elicited unusual interest, particularly those which I performed with a novel form of oscillatory apparatus, which scientific men have since generously identified with my name.  Some time in 1892, on my return from abroad, I constructed and improved apparatus for the purpose of carrying on my practical research of tuned circuits, and I believe in 1893 I lectured before the Franklin Institute and the National Electric Light Association and recorded results still further advanced along the same lines. In these lectures I gave the first outline of a system of transmitting intelligence.  Subsequently, I turned my efforts to developing these ideas and results along practical lines.  These efforts resulted in numerous improvements which I gradually made and which I have covered by a considerable number of patents in the United States and foreign countries.  They relate to methods and apparata for the production of electrical oscillations and means and methods for transmitting electrical energy without wires.  In the last two years my energies have been largely taken up by the construction of commercial plants. . . .

23 Q. Can you describe any other forms of receiver which you used in practicing this invention prior to your Colorado trip?
   A. Yes, sir; I can describe a number of such instruments I used.  One in particular, of which I have already spoken, I believe.  This was a coil wound around a cylinder of large diameter covered on top with a board so that it resembled a table on which I often placed the apparatus for receiving.  Within this coil was another coil, and the terminals of both were led to the board so as to be readily accessible.  I very frequently used this apparatus in the following way: I would pass through the cable laid around the room two electrical oscillations of different periods and would tune one of the coils mentioned to one of the oscillations, and the other to the other oscillation.  I used frequently condensers and inductances for this purpose.  As stated before, this apparatus was very convenient to use because I was familiar with the vibrations, the constants of the circuits, and all other particulars, and could complete the test in a very short time. To give an idea I may mention the article in the Century of April, 1895, by T. C. Martin, in which such an instrument is shown in Figures 9 and 10.  This apparatus illustrated in the Century article was, however, destroyed by fire, but in my laboratory in Houston Street I constructed a similar one, which I have frequently used as stated. Besides this, I had a great many other apparata of this kind which I frequently employed in my demonstrations or lectures with tuned circuits.  I may mention, for instance, a coil which was provided with a handle to which one of its ends was attached, the other end being connected to a loop of rather thick aluminum wire, which served as capacity terminal.  On the lower end of the coil, near the handle, was wound another coil of few turns of wire, to which I often connected a small condenser, adjusting its capacity so that the coil was powerfully excited when a certain vibration was passed through the cable around the room, the other coil responding to another vibration, properly chosen, so that both vibrations would not greatly interfere with each other. It was a common experiment with me to take a hoop of wire closed through a minute lamp and light the latter by the conjoint action of the two coils.  In fact, I was compelled to adopt this expedient because frequently in my demonstrations, when I showed my experiments to an audience, it would happen that when I wanted to operate single circuits with some devices more than one circuit would respond, and people would call my attention to this, and I would then have to say that the circuits were not carefully tuned. But, by adopting two vibrations through the cable around the room I could always manage to operate one single device out of a great many.  Besides this coil, which I frequently used, I had probably a dozen of others, similarly constructed and adjusted, which I showed on many occasions.

24 Q. Please describe the details of the construction of this hoop and lamp, and the manner in which the lamp was operated by the conjoint effect of the two oscillations.
   A. I will give a description of the apparatus as closely as I am able to do now from memory. I think the coil, which was wound on the outer side of the frame of cardboard, about 30 inches in diameter and 5 inches wide, had something like 300 turns of wire--I should say No. 20.  One end of this wire was connected, as I stated before, to a metallic handle, and the other to an aluminum wire, fastened on the end of the frame opposite to the handle, so as to form a circle, which, however, was not closed.  This aluminum wire, constituting what I have called the capacity terminal, was bare, because when the action was powerful I would get strong streamers from it.  On the inner side of the cardboard frame were wound several turns of thicker wire, and these were connected, in the experiment, to a small condenser which was so proportioned that the period of oscillation of the circuit connected to it was suitable for the test, and different from the period of the other circuit which I have first mentioned.  The transmitting apparatus most frequently used was already described in answer to question 15.  It comprised two or more sets of condensers, which were charged from the transformer giving a pressure of 50,000 volts and discharge, in most cases alternately and in very rapid succession, through the cable around the room.  I would then take a loop of wire forming a circle, to which a device such as a minute lamp requiring an extremely small amount of energy was connected, and would approach the loop to the active system of the two circuits, energized in extremely rapid succession from the cable around the room, and the lamp would be lighted; or, another device which I used, operated by the combined action of the two circuits, while other tuned circuits which were in the room would not be perceptibly influenced.  I refer to this experiment simply to illustrate one of the many ways in which I illustrated the invention in my laboratory from 1898 until I moved to Wardenclyffe, recently, in the spring.

25 Q. Please explain with reference to the last experiment to what cause the current in the loop, including the lamp, was due, and in what way the combined action of the two coils was necessary to the operation of the lamp?
   A. The loop containing the lamp was, of course, excited by both circuits in rapid succession, but the minute filament had no time to cool down, so that the action of the two circuits on the loop, and consequently on the lamp, or other device connected to it, was practically simultaneous and cumulative. In other words, the lamp was lighted by the conjoint action of both the circuits, whereas it would not have been lighted by a single one, at least not the way I adjusted the conditions. . . .

81 x-Q. In answering question 10, you give as one reason for going to Colorado that you "wanted to be free of the disturbing influences in the city," and that you recognized a necessity for carrying the invention in question to a further state of perfection.  Did this further experimentation which you desired concern matters effecting the practicability, I mean the commercial practicability of the inventions in question?
A. I do not think that it is novel to those who are acquainted with delicate electrical instruments, such as tuned circuits, that they are very frequently disturbed in the city, such as New York, through which there are continuous leaking currents from power stations, and which is subjected to numerous other disturbances capable of affecting the working of instruments.  The perfection of tuning, considered as an art, can be carried forward indefinitely, at least in theory, and no one can say, however skillful he be, that he has reached the ultimate perfection which it is possible at attain.  Tuning is my specialty, and it is very likely that I might have done better than many others, yet I felt that I ought to still further improve in the knowledge of the same and in the skill of applying it.  The system, as I practiced it, before I went to Colorado, was fully capable of being commercially applied, but, of course, in order to realize what I had proposed myself--the transmission of signals across the seas, and to any terrestrial distance--I had of necessity, for this reason alone, to leave the city.  To begin with, I could not have operated in the city a transmitter producing disturbances of such immense power as I contemplated to obtain, and then again the measurements and other observations which I had to make in gradually perfecting the apparatus could not have been made with that degree of precision of which they were capable in such a locality as the one which I had selected.  These were, however, only a few of a great many reasons which prompted me to go there.

87 x-Q. You have referred to Figures 9 and 10 of the Century article of April 1895. Did you say that these two figures show two receiving coils adapted to receive two sets of impulses of different periodicities?
A. There were two circuits in the apparatus shown in these figures.  In Figure 9 a loop of wire will be seen, while below it there is a coil of comparatively many turns.   These receiving circuits usually have been adopted by me for practicing the invention in the manner described, if I would have had my present knowledge, or even the knowledge which I have had at the time when I began to practice it.  As stated before, this apparatus was destroyed by fire, and another apparatus, already described, was constructed in my laboratory at Houston Street, I think sometime in 1895.  This was the apparatus--to be more explicit--which I have used in actuating by electromagnetic induction, a device through the conjoint action of two tuned circuits.

88 x-Q. Please state whether or not Figure 11 illustrates the lamp receiver which you have already referred to in your testimony?  If it does not, please explain wherein it differs.
A. No, sir, this lamp was lighted by the action of one single circuit, which is below under the cloth The circuit which energized the loop held in the hand of the experimenter was, I believe, covered with black cloth, so as to get a better picture.  The photograph was, I think, also taken by Mr. Alley.

  Nikola Tesla's technological legacy
     The setting
Tesla-Fessenden U.S. Patent Office Interference Case Transcript
Remote Control and The AND Logic Gate
  The beginnings of remote control
     Remote-controlled devices
     Tesla's wireless-controlled boats
     Need for secure control
     Tesla's "individualization" concept
     Later contenders
     Guided weapons
  The AND logic gate
     Electronic elements
     Non-electronic elements
       Fluid logic elements
         Tesla turbine
     High frequency, high voltage, conjoint oscillations
       demonstrating the AND function
     Progenitor of the computer industry
     A. U.S. Patent No. 613,809, "Method and Apparatus for Controlling Mechanism of Moving Vessel or Vehicles," Nov. 8, 1898.
     B. U.S. Patent No. 645,576, "System of Transmission of Electrical Energy," Mar. 20, 1900.
     C. U.S. Patents, Nos. 685,953, 685,954, 685,955, and 685,956, Nov. 5, 1901, on utilizing effects transmitted through natural media.
     D. The AND logic-gate patents
       U.S. Patent No. 723,188, "Method of Signaling," Mar. 17, 1903.
       U.S. Patent No. 725,605, "System of Signaling," Apr. 14, 1903.
     E. U.S. Patent No. 787,412, "Art of Transmitting Electrical Energy Through the Natural Mediums," Apr. 18, 1905.
     F. "Inductorium"
     G. Tesla correspondence with Benjamin Franklin Miessner

Continues the series making available primary documents relating to the Serbian-born American inventor Tesla (1856-1943) around whom something of a cult has developed.  Nearly half of the volume is devoted to the transcript of a hearing over a patent dispute about radio transmission and remote control devices.  Other documents include letters to and from him, photographs, and the text of patents relating both to remote control and the AND logic gate, which foreshadowed electronic computers. 

About the author

Leland I. Anderson is a technical writer and electrical engineer who lives in Denver, Colorado.  His long-time interest in Nikola Tesla took root in the early 1950s, and his activities since then have resulted in his recognition as one of the world's foremost Tesla historians.  His works include the monographs Priority in the Invention of Radio, Tesla vs. Marconi and Ball Lightning & Tesla's Electric Fireballs, and the books Nikola Tesla On His Work With Alternating Currents, Nikola Tesla—Lecture Before the New York Academy of Sciences, April 6, 1897, and Nikola Tesla's Teleforce & Telegeodynamics Proposals.


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