 Appendix three of Edison his life and inventions. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Heidi Preuss. Edison his life and inventions by Frank Louis Dyer and Thomas Comerford Martin. Appendix three. Automatic Telegraphy. From the year 1848, when a Scotsman, Alexander Bain, first devised a scheme for rapid telegraphy by automatic methods, down to the beginning of the 70s, many other inventors had also applied themselves to the solution of this difficult problem with only indifferent success. With cheap telegraphy being the slogan of the time, Edison became arduously interested in the subject and, at the end of three years of hard work, produced an entirely successful system, a public test of which was made on December 11, 1873, when about 12,000 words were transmitted over a single wire from Washington to New York in twenty-two and one-half minutes. Edison's system was commercially exploited for several years by the automatic telegraph company as related in the preceding narrative. As a premise to an explanation of the principles involved that the transmission of telegraph messages by hand at a rate of fifty words per minute is considered a good average speed. Hence the availability of a telegraph line, as thus operated, is limited to this capacity except as it may be multiplied by two with the use of the duplex or by four with the quadruplex. Increased rapidity of transmission may, however, be accomplished by automatic methods by means of which, through the employment of suitable devices, messages may be stamped in or upon a paper tape transmitted through automatically acting instruments and be received at distant points invisible characters upon a similar tape at a rate twenty or more times greater, a speed far beyond the possibilities of the human hand to transmit or the ear to receive. In Edison's system of automatic telegraphy a paper tape was perforated with a series of round holes so arranged and spaced as to represent Morse characters forming the words of the message to be transmitted. This was done in a special machine of Edison's invention called the perforator consisting of a series of punches operated by a bank of keys typewriter fashion. The paper tape passed over a cylinder and was kept in regular motion so as to receive the perforations in proper sequence. The perforated tape was then placed in the transmitting instrument, the essential parts of which were a metallic drum and a projecting arm carrying two small wheels which by means of a spring were maintained in constant pressure on the drum. The wheels and drum were electrically connected in the line over which the message was to be sent, current being supplied by batteries in the ordinary manner. When the transmitting instrument was in operation the perforated tape was passed over the drum in continuous progressive motion. Thus the paper passed between the drum and the two small wheels and as dry paper is a nonconductor current was prevented from passing until a perforation was reached. As the paper passed along the wheels dropped into the perforations making momentary contacts with the drum beneath and causing momentary impulses of current to be transmitted over the line in the same way that they would be produced by the manipulation of the telegraph key but with much greater rapidity. The perforations being so arranged as to regulate the lengths of the contact the result would be the transmission of long and short impulses corresponding with the dots and dashes of the Morse alphabet. The receiving instrument at the other end of the line was constructed upon much the same general lines as the transmitter consisting of a metallic drum and reels for the paper tape. Instead of the two small contact wheels however a projecting arm carried an iron pin or stylus so arranged that its point would normally impinge upon the periphery of the drum. The iron pin and the drum were respectively connected so as to be in circuit with the transmission line and batteries. As the principle involved in the receiving operation was electrochemical decomposition the paper tape upon which the incoming message was to be received was moistened with a chemical solution readily decomposable by the electric current. This paper while still in a damp condition was passed between the drum and the stylus in continuous progressive motion. When an electrical impulse came over the line from the transmitting end current passed through the moistened paper from the iron pin causing chemical decomposition by reason of which the iron would be attacked and would mark a line on the paper. Such a line would be long or short according to the duration of the electrical impulse. In as much as a succession of such impulses coming over the line owed their origin to the preparations in the transmitting tape it followed that the resulting marks upon the receiving tape would correspond there too in their respective length. Hence the transmitted message was received on the tape in visible dots and dashes representing characters of the Morse alphabet. The system will perhaps be better understood by reference to the following diagrammatic sketch of its general principles. Some idea of the rapidity of automatic telegraphy may be obtained when we consider the fact that with the use of Edison's system in the early 70s it was common practice to transmit and receive from three or four thousand words a minute over a single line between New York and Philadelphia. This system was exploited through the use of a moderately paid clerical force. In practice there was employed such a number of perforating machines as the exigency of business demanded. Each machine was operated by a clerk who translated the message into telegraphic characters and prepared the transmitting tape by punching the necessary perforations therein. An expert clerk could perforate such a tape at the rate of fifty to sixty words per minute. At the receiving end the tape was taken by other clerks who translated the Morse characters into ordinary words which were written on message blanks for delivery to persons for whom the messages were intended. This latter operation, copying as it was called, was not consistent with truly economical business practice. Edison therefore undertook the task of devising an improved system whereby the message, when received, would not require translation and rewriting but would automatically appear on the tape in plain letters and words ready for instant delivery. The result was his automatic Roman letter system, the basis for which included the above-named general principles of perforated transmission tape and electrochemical decomposition. Instead of punching Morse characters in the transmission tape, however, it was perforated with a series of small round holes forming Roman letters. The verticals of these letters were originally five holes high. The transmitting instrument had five small wheels or rollers instead of two for making contacts through the perforations and causing short electrical impulses to pass over the lines. At first five lines were used to carry these impulses to the receiving instrument where there were five iron pins impinging on the drum. By means of these pins the chemically prepared tape was marked with dots corresponding to the impulses as received, leaving upon it a legible record of the letters and words transmitted. For the purposes of economy and investment in maintenance Edison devised subsequently a plan by which the number of conducting lines was reduced to two instead of five. The verticals of the letters were perforated only four holes high and the four rollers were arranged in pairs, one pair being slightly in advance of the other. There were, of course, only four pins at the receiving instrument. Two were of iron and two of tellurium. It being the gist of Edison's plan to affect the marking of the chemical paper by one metal with a positive current and by the other metal with a negative current. In the following diagram which shows the theory of this arrangement it will be seen that both the transmitting rollers and the receiving pins are arranged in pairs, one pair in each case being slightly in advance of the other. Of these receiving pins one pair one and three are of iron and the other pair two and four are of tellurium. Pins one two and three four are electrically connected together in other pairs and then each of these pairs is connected with one of the main lines that runs respectively to the middle of the groups of batteries at the transmitting end. The terminals of these groups of batteries are connected respectively to the four rollers which impinge upon the transmitting drum. The negatives being connected to five and seven and the positives to six and eight as the noted by the letters N and P. The transmitting and receiving drums are respectively connected to earth. In operation the perforated tape is placed on the transmission drum and the chemically prepared tape on the receiving drum. As the perforated tape passes over the transmission drum the advance rollers six or eight first close the circuit through the perforations and a positive current passes from the batteries through the drum and down to the ground. Then through the earth at the receiving end up to the other drum and back to the batteries via the tellurium pins two or four and the line wire. With this positive current the tellurium pins make marks upon the paper tape but the iron pins make no mark. In the nearest fraction of a second as the perforated paper continues to pass over the transmission drum. Rollers five or seven close the circuit through other perforations and current passes in the opposite direction over the line wire through pins one or three and return through the earth. In this case the iron pins mark the paper tape but the tellurium pins make no mark. It will be obvious therefore that as the rollers are set so as to allow of currents of opposite polarity to be alternately and rapidly sent by means of the perforations the marks upon the tape at the receiving station will occupy their proper relative positions and the aggregate result will be letters corresponding to those perforated in the transmission tape. Edison subsequently made further improvements in this direction by which he reduced the number of conducting wires to one but the principles involved were analogous to the one just described. This Roman letter system was in use for several years on lines between New York, Philadelphia and Washington and was so efficient that a speed of three thousand words a minute was attained on the line between the first two named cities. In as much as there were several proposed systems of rapid automatic telegraphy in existence at the time Edison entered the field but none of them in practical commercial use it becomes a matter of interest to inquire wherein they were deficient and what constituted the elements of Edison's success. The chief difficulties in transmission of Morse characters had been two in number the most serious of which was that on the receiving tape the characters would be prolonged and run into one another forming a draggled line and thus rendering the message unintelligible. This arose from the fact that on account of the rapid succession of electric impulses there was not sufficient time between them for the electric action to cease entirely. Consequently the line would not clear itself and become surcharged as it were. The effect being an attenuated prolongation of each impulse as manifested in a weaker continuation of the mark on the tape thus making the whole message indistinct. These secondary marks were called tailings. For many years electricians had dried in vain to overcome this difficulty. Edison devoted a great deal of thought and energy to the question in the course of which he experimented through 120 consecutive nights in the year of 1873 on the line between New York and Washington. His solution of the problem was simple but effectual. It involved the principle of inductive compensation in a shunt circuit with the receiving instrument he introduced electromagnets. The pulsations of the current passed through the helices of these magnets producing an augmented marking effect upon the receiving tape. But upon the breaking of the current the magnet in discharging itself of the induced magnetism would set up momentarily a countercurrent of opposite polarity. This neutralized the tailing effect by clearing the line between pulsations thus allowing the telegraphic characters to be clearly and distinctly outlined upon the tape. Further elaboration of this method was made later by the addition of real stats, condensers, and local opposition batteries on long lines. The other difficulty above reference to was one that had also occupied considerable thought and attention of many workers in the field and related to the perforating of the dash in the transmission tape. It involved mechanical complications that seemed to be insurmountable and up to the time Edison invented his perforating machine no really good method was available. He abandoned the attempt to cut dashes as such in the paper tape but instead punched three round holes so arranged as to form a triangle. A concrete example is presented in the illustration below which shows a piece of tape with preparations representing the word same. The philosophy of this will at once be perceived when it is remembered that the two wheels running upon the drum of the transmitting instrument were situated side by side corresponding in distance to the two rows of holes. When a triangle of three holes intended to form the dash reached the wheels one of them dropped into a lower hole. Before it could get out the other wheel dropped into the hole at the apex of the triangle thus continuing the connection which was still further prolonged by the first wheel dropping into the third hole. Thus an extended contact was made which by transmitting a long impulse resulted in the marking of a dash upon the receiving tape. This method was in successful commercial use for some time in the early seventies giving a speed of from three to four thousand words a minute over a single line but later on was superseded by Edison's Roman letter system above referred to. The subject of automatic telegraphy received a vast amount of attention from investors at the time it was in vogue. None was more earnest or indefatigable than Edison who during the progress of his inventions took out thirty eight patents on various inventions relating there to some of them covering chemical solutions for the receiving paper. This of itself was a subject of much importance and a vast amount of research and labor was expended upon it. In the laboratory notebooks there are recorded thousands of experiments showing that Edison's investigations not only included an enormous number of chemical salts and compounds but also an exhaustive variety of plants, flowers, roots, herbs and barks. It seems inexplicable at first view that a system of telegraphy sufficiently rapid and economical to be practically available for important business correspondence should have fallen into disuse. This however is made clear so far as concerns Edison's inventions at any rate in chapter eight of the preceding narrative. End Appendix 3. Appendix 4 of Edison, His Life and Inventions. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org. Recording by Heidi Preuss. Edison, His Life and Inventions by Frank Louis Dyer and Thomas Comerford Martin. Appendix 4. Wireless Telegraphy. Although Mr. Edison has taken no active part in the development of the more modern wireless telegraphy and his name has not occurred in connection therewith, the underlying phenomena had been noted by him many years in advance of the art, as will presently be explained. The authors believe that this explanation will reveal a status of Edison in relation to the subject that has thus far been unknown to the public. While the term wireless telegraphy has now applied to the modern method of electrical communication between distant points without intervening conductors is self-explanatory, it is also applicable, strictly speaking, to the previous art of telegraphing to and from moving trains and between points not greatly remote from each other and not connected together with wires. The latter system, described in Chapter 23 and in a succeeding article of this Appendix, was based upon the phenomena of electric magnetic or electrostatic induction between conductors separated by more or less space, whereby electric impulses of relatively low potential and low frequency set up in one conductor were committed inductively across the air to another conductor and they're received through the medium of appropriate instruments connected therewith. As distinguished from this system, however, modern wireless telegraphy, so-called, has basis in the utilization of electric or ether waves in free space, such waves being set up by electric oscillations or surging of comparatively high potential and high frequency produced by the operation of suitable electrical apparatus. Broadly speaking, these oscillations arise from disruptive discharges of an inductive coil or other form of oscillator across an air gap and their character is controlled by the manipulation of a special type of circuit breaking key by means of which long and short discharges are produced. The electric or etheric waves, thereby set up, are detected and received by another special form of apparatus more or less distant without any intervening wires or conductors. In November 1875, Edison, while experimenting in his Newark laboratory, discovered a new manifestation of electricity through mysterious sparks which could be produced under conditions unknown up to that time. Recognizing at once the absolutely unique character of the phenomena, he continued his investigations enthusiastically over two months, finally arriving at a correct inclusion as to the oscillatory nature of the hitherto unknown manifestations. Strange to say, however, the true impact and practical applicability of these phenomena did not occur to his mind. Indeed, it was not until more than twelve years afterwards in 1887 upon the publication of the notable work of Professor H. Hertz proving the existence of electric waves in free space that Edison realized the fact that the fundamental principle of aerial telegraphy had been within his grasp in the winter of 1875. For although the work of Hertz was more profound and mathematical than that of Edison, the principle involved and the phenomena observed were practically identical. In fact, it may be remarked that some of the methods and experimental apparatus were quite similar, especially the dark box with micrometer adjustment used by both in observing the spark. 25. During the period in which Edison exhibited his lightning system at the Paris Exposition in 1881, his representative Mr. Charles Bachelore repeated Edison's remarkable experiments of the winter of 1875 for the benefit of a great number of European savants using with other apparatus the original dark box with micrometer adjustment. There is not the slightest intention on the part of the authors to detract in the least degree from the brilliant work of Hertz. On the contrary, to ascribe to him the honor that is his due in having given mathematical direction and certainty to so important a discovery. The adaptation of the principles thus elucidated and the subsequent development of the present wonderful art by Marconi, Branley, Lodge, Slabby and others are now too well known to call for further remark at this place. Strange to say that although Edison's early experiments in etheric force called forth extensive comment and discussion in the public prints of the period, they seem to have been generally overlooked when the work of Hertz was published. At a meeting of the institution of electrical engineers held in London on May 16, 1889, at which there was a discussion on the celebrated paper of Professor Sir Oliver Lodge on lightning conductors, however, the chairman, Sir William Thompson, Lord Kelvin, made the following remark. We all know how Faraday made himself a cage six feet in diameter, hung it up in mid-air in the theatre of the Royal Institution, went into it, and, as he said, lived in it and made experiments. It was a cage with tinfoil hanging all around it. It was not a complete metallic enclosing shell. Faraday had a powerful machine working in the neighbourhood, giving all varieties of gradual working up and discharges by impulsive rush, and whether it was a sudden discharge of ordinary insulated conductors or of laden jars in the neighbourhood outside the cage, or electrification and discharge of the cage itself, he saw no effect on his most delicate gold leaf electroscopes in the interior. His attention was not directed to look for Hertz sparks, or probably he might have found them in the interior. Edison seems to have noticed something of the kind in what he called the Etheric force. His name Etheric, May 13 years ago, have seemed to many people absurd, but now we are all beginning to call these inductive phenomena Etheric. With these preliminary observations, let us now glance briefly at Edison's laboratory experiments, of which mention has been made. On the first manifestation of the unusual phenomena in November 1875, Edison's keenness of perception led him at once to believe that he had discovered a new force. Indeed, the earliest entry of this discovery in the laboratory notebook bore that caption. After a few days of further experiment and observation, however, he changed it to Etheric force, and the further records thereof, all in Mr. Bachelors' handwriting, were under that heading. The publication of Edison's discovery created considerable attention at the time, calling forth a storm of general ridicule and incredulity. But a few scientific men of the period, whose experimental methods were careful and exact, corroborated his deductions after obtaining similar phenomena by repeating his experiments with intelligent precision. Among these was the late Dr. George M. Beard, a noted physicist who entered enthusiastically into the investigation and, in addition to a great deal of independent experiment, spent much time with Edison at his laboratory. Dr. Beard wrote a treatise of some length on the subject, in which he concurred with Edison's deduction that the phenomena were the manifestation of oscillations, or rapidly reversing waves of electricity, which did not respond to the usual tests. Edison had observed the tendency of this force to diffuse itself in various directions through the air and through matter, hence the name Etheric that he had provisionally applied to it. Edison's laboratory notes on this striking investigation are fascinating and voluminous, but cannot be reproduced in full for lack of space. In view of the latter practical application of the principles involved, however, the reader will probably be interested in perusing the few extracts therefrom, as illustrated by facsimiles of the original sketches from the laboratory notebook. As the full significance of the experiments shown by these extracts may not be apparent to a lay reader, it may be stated by way of premise that ordinarily a current only follows a closed circuit. An electric bell or electric light is a familiar instance of this rule. There is in each case an open wire, circuit, which is closed by pressing the button or turning the switch, thus making a complete and uninterrupted path in which the current may travel and do its work. Until the time of Edison's investigations of 1875, now under consideration, electricity had never been known to manifest itself except through its closed circuit. But as the reader will see from the following excerpts, Edison discovered a hitherto unknown phenomenon, namely that under certain conditions the rule would be reversed and electricity would pass through space and through matter entirely unconnected with its point of origin. In other words, he had found the forerunner of wireless telegraphy. Had he then realized the full import of his discovery, all he needed was to increase the strength of the waves and to provide a very sensitive detector, like the co-hearer, in order to have anticipated the principal developments that came many years afterwards. With these explanatory observations we will now turn to the excerpts referred to which are as follows. November 22, 1875. New Force. In experimenting with a vibrator magnet consisting of a bar of stubbed steel fastened at one end and made to vibrate by means of a magnet, we noticed a spark coming from the cores of the magnet. This we have noticed often in relays and stock printers, when there were a little iron filings between the armature and core, and more often in our new electric pen, and we have always come to the conclusion that it was caused by strong induction. But when we noticed it on this vibrator, it seemed so strong that it struck us forcibly there might be something more than induction. We now found that if we touched any metallic part of the vibrator or magnet, we got the spark. The larger the body of iron touched to the vibrator, the larger the spark. We now connected a wire to X, the end of the vibrating rod, and we found we could get a spark from it by touching a piece of iron to it. And one of the more curious phenomena is that if you turn the wire around on itself and let the point of the wire touch any other portion of itself, you get a spark. By connecting X to the gas pipe, we drew sparks from the gas pipes in any part of the room by drawing an iron wire over the brass jet of the caulk. This is simply wonderful and a good proof that the cause of the spark is a true unknown force. November 23, 1815. New Force. The following very curious result was obtained with it. The vibrator shown in Figure 1 and Battery were placed on insulated stands and a wire connected to X, tried both copper and iron, carried over to the stove about 20 feet distant. When the end of the wire was rubbed on the stove, it gave out splendid sparks. When permanently connected to the stove, sparks could be drawn from the stove by a piece of wire held in the hand. The point X of the vibrator was now connected to the gas pipe and still sparks could be drawn from the stove. Put a coil of wire over the end of rod X and passed the ends of spool through galvanometer without affecting it in any way. Tried a 6 ohm spool, add a 200 ohm. We now tried all the metals touching each one in turn to the point X. Here follows a list of metals and the character of sparks obtained with each. By increasing the battery from 8 to 12 cells, we get a spark when the vibrating magnet is shunted with 3 ohms. Cannot taste the least shock at B, yet between carbon points the spark is very vivid. As we'll be seeing, X has no connection with anything. With a glass rod 4 feet long, well rubbed with a piece of silk over a hot stove with a piece of battery carbon secured to one end, we receive vivid sparks into the carbon when the other end was held in the hand with the handkerchief. Yet the galvanometer, chemical paper, the sense of shock in the tongue, and a gold leaf electroscope, which would diverge at 2 feet from a half inch spark plate glass machine, were not affected in the least by it. A piece of coal held to the wire showed faint sparks. We had a box made thus whereby two points could be brought together within a dark box provided with an eyepiece. The points were iron and we found the sparks were very irregular. After testing some time, two lead pencils found more regular and very much more vivid. We then substituted the graphite points instead of iron, 26. 26. The dark box had micrometer screws for delicate adjustment of the carbon points and was thereafter largely used in this series of investigations for better study of the spark. When Mr. Edison's experiments were repeated by Mr. Batchelor, who represented him at the Paris Exposition of 1881, the dark box was employed for a similar purpose. After recording a considerable number of other experiments, the laboratory notes go on to state. November 30, 1875. Etheric force. We found the addition of battery to the Stubbs wire vibrator greatly increased the volume of the spark. Several persons could obtain sparks from the gas pipe at once, each spark being equal in volume and brilliancy to the spark drawn by a single person. Edison now grasped the gas pipe and with the other hand holding a piece of metal, he touched several other metallic substances, obtained sparks showing that the force passed through his body. December 3, 1875. Etheric force. Charlie Edison hung to the glass pipe with feet above the floor and with a knife got sparks from the pipe he was hanging on. We now took the wire from the vibrator in one hand and stood on a block of paraffin 18 inches square and 6 inches thick. Holding a knife in the other hand, we drew sparks from the stove pipe. We now tried the crucial test of passing the Etheric current through the sciatic nerve of a frog just killed. Previous to trying, we tested its sensibility by current from a single Bunsen cell. We put in resistance up to 500,000 ohms and the twitching was still perceptible. We tried the induced current from our induction coil having one cell on primary. The spark jumping about one-fiftieth of an inch, the terminal of the secondary connected to the frog and it straightened out in violence. We arranged frog's legs to pass Etheric force through. We placed legs on an inverted beaker and held the two ends of the wire on glass rods 8 inches long. On connecting one to the sciatic nerve and the other to the fleshy part of the leg no movement could be discerned. Although brilliant sparks could be obtained on the graphite points when the frog was in current. Dr. Beard was present when this was tried. December 5, 1875 Etheric force. Three persons grasping hands and standing upon blocks of paraffin 12 inches square and 6 thick drew sparks from the adjoining stove when another person touched the sounder with any piece of metal. A galvanoscopic frog giving contractions with one cell through the water rheostats was placed in circuit. When the wires from the vibrator and the gas pipe were connected slight contractions were noticed sometimes very plain and marked showing the apparent presence of electricity which from the high insulation seemed improbable. Dr. Beard who was present inferred from the way the leg contracted that it moved on both opening and closing the circuit. To test this we disconnected the wire between the frog and the battery and placed instead of a vibrating sounder a simple Morse key and a sounder taking the Etheric from armature. The spark was now tested in dark box and found to be very strong. It was then connected to the nerves of the frog but no movement of any kind could be detected upon working the key although the brilliancy and power of the spark were undiminished. The thought then occurred to Edison that the movement of the frog was due to mechanical vibrations from the vibrator which gives probably 250 vibrations per second. Passing through the wires and irritating the sensitive nerves of the frog. Upon disconnecting the battery wires and holding a tuning fork giving 326 vibrations per second to the base of the sounder the vibrations over the wire made the frog contract nearly every time. The contraction of the frog's legs may be with considerable safety be said to be caused by these mechanical vibrations being transmitted through the conducting wires. Edison thought that the longitudinal vibrations caused by the sounder produced a more marked effect and proceeded to try out his theory. The very next entry in the laboratory notebook bears the same date as the above December 5 1875 and is entitled Longitudinal Vibrations and reads as follows. We took a long iron wire one sixteenth of an inch in diameter and rubbed it lengthways with a piece of leather with resin on for about three feet backward and forwards. About ten feet away we applied the wire to the back of the neck and it gives a horrible sensation showing the vibrations are conducted through the wire. The following experiment illustrates notably the movement of the electric waves through free space. December 26 1875 Etheric Force An experiment tried tonight gives a curious result. A is a vibrator B C D and E are sheets of tin foil hung on insulating strands. The sheets are about 12 by 8 inches B and C are 26 inches apart C and D 48 inches and D and E 26 inches. B is connected to the vibrator and E to point in dark box the other point to ground. We received sparks at intervals although insulated by such space. With the above our extracts must close although we have given but a few of the interesting experiments tried at the time. It will be noticed however that these records show such progression in little over a month. Just after the item last above extracted the Edison shop became greatly rushed on telegraphic inventions and not many months afterwards came the removal to Menlo Park. Hence the Etheric Force investigations were sidetracked for other matters deemed to be more important at that time. Dr. Beard in his previously mentioned treaties refers on page 27 to the views of others who have repeated Edison's experiments and observed the phenomena. And in a footnote says, Professor Houston of Philadelphia among others has repeated some of these physical experiments and has adopted in full and after but a partial study of the subject the hypothesis of rapidly reversed electricity. As suggested in my letter to the Tribune of December 8 and further claims priority of discovery because he observed the spark of this when experimenting with a room corf coil four years ago. To this claim if it be seriously entertained the obvious reply is that thousands of persons probably had seen this spark before it was discovered by Mr. Edison. It had been seen by Professor Neifer who supposed and still supposes it is the spark of the extra current. It has been seen by my friend Professor J. E. Smith who assumed as he tells me without examination that it was inductive electricity breaking through bad insulation. It had been seen as has been stated by Mr. Edison many times before he thought it was worthy of study. It was undoubtedly seen by Professor Houston who like so many others failed to even suspect its meaning and thus missed an important discovery. The honor of a scientific discovery belongs not to him who first sees a thing but to him who first sees it with expert eyes. Not to him even who drops an original suggestion but to him who first makes that suggestion fruitful of results. If to see with the eyes a phenomenon is to discover the law of which that phenomenon is a part then every schoolboy who before the time of Newton ever saw an apple fall was a discoverer of the law of gravitation. Edison took out only one patent on long distance telegraphy without wires. While the principle involved therein induction was not precisely analogous to the above or to the present system of wireless telegraphy it was a step forward in the process of the art. The application was filed May 23 1885 at the time he was working on induction telegraphy two years before the publication of the work of Hertz. But the patent number 465971 was not issued until December 29 1891. In 1903 it was purchased from him by Marconi Wireless Telegraph Company. Edison has always had a great admiration for Marconi and his work and a warm friendship exists between the two men. During the formative period of the Marconi company attempts were made to influence Edison to sell this patent to an opposing concern. But his regard for Marconi and belief in the fundamental nature of his work were so strong that he refused flatly. Because in the hands of an enemy the patent might be used inaminically to Marconi's interests. Edison's ideas as expressed in the specification of this patent show very clearly the close analogy of his system to that now invoke. As they were filed in the patent office several years before the possibility of wireless telegraphy was suspected it will undoubtedly be of interest to give the following extract therefrom. I have discovered that if sufficient elevation be obtained to overcome the curvature of the Earth's surface and to reduce to the minimum the Earth's absorption, electric telegraphing or signaling between distant points can be carried on by induction without the use of wires connecting such distant points. This discovery is especially applicable to telegraphing across bodies of water thus avoiding the use of submarine cables or for communicating between vessels at sea or between vessels at sea and points of land. But it is also applicable to electric communication between distant points on land. It being necessary however on land with the exception of communication over open prairie to increase the elevation in order to reduce the minimum the induction absorbing effect of houses, trees and elevations in the land itself. At sea from an elevation of 100 feet I can communicate electrically at great distance and since this elevation or one sufficiently high can be had by utilizing the mass of ships, signals can be sent and received between ships separated a considerable distance. And by repeating the signals from ship to ship communication can be established between points at any distance apart or across the largest seas and even oceans. The collision of ships in fog can be prevented by this character of signaling by the use of which also the safety of a ship in approaching a dangerous coast in foggy weather can be assured. In communicating between points on land poles of great height can be used or captive balloons. At these elevated points whether upon the mass of ships upon poles or balloons condensing surfaces of metal or other conductor of electricity are located. Each condensing surface is connected with earth by an electrical conducting wire. On land this earth connection would be one of usual character in telegraphy. At sea the wire would run to one or more metal plates on the bottom of the vessel where the earth connection would be made with the water. The high resistance secondary circuit of an induction coil is located in circuit between the condensing surface and the ground. The primary circuit of the induction coil includes a battery and a device for transmitting signals which may be a revolving circuit breaker operated continually by a motor of any suitable kind either electrical or mechanical. And a key normally short circuiting the circuit breaker or secondary coil. For receiving signals I locate in said circuit between the condensing surface and the ground a diaphragm sounder which is preferably one of my electromotograph telephone receivers. The key normally short circuiting the revolving circuit breaker no impulses are produced in the induction coil until the key is depressed. When a large number of impulses are produced in the primary and by means of the secondary corresponding impulses or variations in tension are produced at the elevated condensing surface producing there at electrostatic impulses. These electrostatic impulses are transmitted inductively to the elevated condensing surface at the distant point and are made audible by the electromotograph connected to the ground circuit with such distant condensing surface. The accompanying illustrations are reduced facsimiles of the drawings attached to the above patent number 465971. End of appendix 4 Appendix 5 of Edison, his life and inventions. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org recording by Anna Simon. Edison, his life and inventions by Frank Lewis-Dyer and Thomas Comerford-Martin. Appendix 5, the electromotograph. In solving a problem that at the time was thought to be insurmountable and in the adaptability of its principles to the successful overcoming of apparently insuperable difficulties subsequently arising in other lines of work, this invention is one of the most remarkable of the many that Edison has made in his long career as an inventor. The object primarily sought to be accomplished was the repeating of telegraphic signals from a distance without the aid of a galvanometer or an electromagnetic relay to overcome the claims of the page patent referred to in the preceding narrative. This object was achieved in the device described in Edison's basic patent number 158,787 issued January 19, 1875 by the substitution of friction and anti-friction for the presence and absence of magnetism in a regulation relay. It may be observed parenthetically for the benefit of the delay reader that in telegraphy the device known as the relay is a receiving instrument containing an electromagnet adapted to respond to the weak line current. Its armature moves in accordance with electrical impulses or signals transmitted from a distance and in so responding operates mechanically to alternately close and open a separate local circuit in which there is a sounder and a powerful battery. When used for true relaying purposes the signals received from a distance are in turn repeated over the next section of the line, the powerful local battery furnishing current for this purpose. As this causes a loud repetition of the original signals it will be seen that relaying is an economic method of extending a telegraph circuit beyond the natural limits of its battery power. At the time of Edison's invention, as related in Chapter 9 of the preceding narrative, there existed no other known method than the one just described for the repetition of transmitted signals, thus limiting the application of telegraphy to the pleasure of those who might own any patent controlling the relay, except on simple circuits where a single battery was sufficient. Edison's previous discovery of differential friction of surfaces through electrochemical decomposition was now adapted by him to produce motion at the end of a circuit without the intervention of an electromagnet. In other words he invented a telegraph instrument having a vibrator controlled by electrochemical decomposition to take the place of a vibrating armature operated by an electromagnet and thus opened an entirely new and unsuspected avenue in the art. Edison's electromotograph comprised an ingeniously arranged apparatus in which two services, normally in contact with each other, were caused to alternately adhere by friction or slip by reason of electrochemical decomposition. One of these services consisted of a small drum or cylinder of chalk which was kept in a moistened condition with a suitable chemical solution and adapted to revolve continuously by clockwork. The other service consisted of a small pad which rested with frictional pressure on the periphery of the drum. This pad was carried on the end of a vibrating arm whose lateral movement was limited between two adjustable points. Normally the frictional pressure between the drum and the pad would carry the letter with the former as it revolved, but if the friction were removed a spring on the end of the vibrator arm would draw it back to its starting place. In practice the chalk drum was electrically connected with one pole of an incoming telegraph circuit and the vibrating arm and pad with the other pole. When the drum rotated the friction of the pad carried the vibrating arm forward, but an electrical impulse coming over the line would decompose the chemical solution with which the drum was moistened causing an effect similar to the lubrication and thus allowing the pad to slip backward freely in response to the pull of its retractile spring. The frictional movements of the pad with the drum were comparatively long or short and corresponded with the length of the impulses sent in over the line. Thus the transmission of Morse dots and dashes by the distant operator resulted in movements of corresponding length by the frictional pad and vibrating arm. This brings us to the gist of the ingenious way in which Edison substituted the action of electrochemical decomposition for that of the electromagnet to operate a relay. The actual relaying was accomplished through the medium of two contacts making connection with the local or relay circuit. One of these contacts was fixed while the other was carried by the vibrating arm, and as the latter made its forward and backward movements these contacts were ultimately brought together or separated, thus throwing in and out of circuit the battery and soundle in the local circuit and causing a repetition of the incoming signals. The other side of the local circuit was permanently connected to an insulated block on the vibrator. This device not only worked with great rapidity but was extremely sensitive and would respond to currents too weak to affect the most delicate electromagnetic relay. It should be stated that Edison did not confine himself to the working of the electromotograph by the slipping of surfaces through the action of incoming current, but by varying the characters of the surfaces in contact the frictional effect might be intensified by the electrical current. In such a case the movements would be the reverse of those above indicated but the end sought namely the relaying of messages would be attained with the same certainty. While the principal object of this invention was to accomplish the repetition of signals without the aid of an electromagnetic relay, the instrument devised by Edison was capable of use as a recorder also by employing a small wheel inked by a fountain wheel and attached to the vibrating arm through suitable mechanism. By means of this adjunct the dashes and dots of the transmitted impulses could be recorded upon a paper ribbon passing continuously over the drum. The electromotograph is shown diagrammatically in figures 1 and 2 in plan and vertical section respectively. The reference letters in each case indicate identical parts, a being the charcterum, b the paper tape, c the auxiliary cylinder, d the vibrating arm, e the frictional pad, f the spring, g and h the two contacts, i and j the two wires leading to local circuit, k a battery and l an ordinary telegraph key. The two last named k and l are shown to make this sketch complete but in practice would be at the transmitting end which might be hundreds of miles away. It will be understood of course that the electromotograph is a receiving and relaying instrument. Another notable use of the electromotograph principle was in its adaptation to the receiver in Edison's loud speaking telephone on which United States patent number 221957 was issued November 25, 1879. A charcterum moistened with a chemical solution was revolved by hand or a small motor. Resting on the cylinder was a palladium faced pen or spring which was attached to a mica diaphragm in a resonator. The current passed from the main lines through the pen to the charcter to the battery. The sound waves impinging upon the distant transmitter varied the resistance of the carbon button therein thus causing corresponding variations in the strength of the battery current. These variations passing through the charcter cylinder produced more or less electrochemical decomposition which in turn caused differences of adhesion between the pen and cylinder and hence gave rise to mechanical vibrations of the diaphragm by reason of which the speakers words were reproduced. The telephones so operated repeated speaking and singing in very loud tones. In one instance spoken words and the singing of songs originating at a distance were heard perfectly by an audience of over 5,000 people. The loud speaking telephone is shown in section diagrammatically in the sketch figure 3 in which A is a chalk cylinder mounted on a shaft B. The palladium faced pen or spring C is connected to diaphragm D. The instrument in its commercial form is shown in figure 4. End of appendix 5. On April 27, 1877 Edison filed in the United States Patent Office an application for a patent on a telephone, and on May 3, 1892, more than fifteen years afterward, patent number 474-230 was granted thereon. Other patents have been issued to him for improvements in telephones, but the one above specified may be considered as the most important of them, since it is the one that first discloses the principle of the carbon transmitter. This patent embodies but two claims which are as follows. One, in a speaking telegraph transmitter, the combination of a metallic diaphragm and disc of plumbago or equivalent material, the contingent faces of said disc and diaphragm being in contact substantially as described. Two, as a means for effecting a varying surface contact in the circuit of a speaking telegraph transmitter, the combination of two electrodes, one of plumbago or similar material, and both having broad surfaces in vibrating contact with each other substantially as described. The advance that was brought about by Edison's carbon transmitter will be more apparent if we glance first at the state of the art of telephony prior to his invention. Bell was undoubtedly the first inventor of the art of transmitting speech over an electric circuit, but, with his particular form of telephone, the field was circumscribed. Bell's telephone is shown in the diagrammatic sectional sketch, figure one. In the drawing M is a bar magnet contained in the rubber case L, a bobbin, or a coil of wire B surrounds one end of the magnet. A diaphragm of soft iron is shown at D and E is the mouthpiece. The wire terminals of the coil B connect with the binding screws C, C. The next illustration shows a pair of such telephones connected for use, the working parts only being designated by the above reference letters. It will be noted that the wire terminals are here put to their proper uses, two being joined together to form a line of communication, and the other two being respectively connected to ground. Now, if we imagine a person at each one of the instruments, figure two, we shall find that when one of them speaks, the sound vibrations impinge upon the diaphragm and cause it to act as a vibrating armature. By reason of its vibrations, this diaphragm induces very weak electric impulses in the magnetic coil. These impulses, according to Bell's theory, correspond in form to the sound waves and, passing over the line, energize the magnetic coil at the receiving end, thus giving rise to corresponding variations in magnetism by reason of which the receiving diaphragm is similarly vibrated so as to reproduce the sounds. A single apparatus at each end is therefore sufficient, performing the double function of transmitter and receiver. It will be noticed that in this arrangement no battery is used. The strength of the impulses transmitted is therefore limited to that of the necessarily weak induction currents generated by the original sounds, minus any loss arising by reason of resistance in the line. Edison's carbon transmitter overcame this vital or limiting weakness by providing for independent power on the transmission circuit and by introducing the principle of varying the resistance of that circuit with changes in the pressure. With Edison's telephone there is used a closed circuit on which a battery current constantly flows, and in that circuit is a pair of electrodes, one or both of which is carbon. These electrodes are always in contact with a certain initial pressure, so that current will always be flowing over the circuit. One of the electrodes is connected with the diaphragm on which the sound waves impinge, and the vibrations of this diaphragm cause corresponding variations in pressure between the electrodes and thereby affect similar variations in the current which is passing over the line to the receiving end. This current flowing around the receiving magnet causes corresponding impulses therein, which acting upon its diaphragm effect a reproduction of the original vibrations and hence of the original sounds. In other words the essential difference is that with Bell's telephone the sound waves themselves generate the electric impulses which are therefore extremely faint. With Edison's telephone the sound waves simply actuate an electric valve, so to speak, and permit variations in a current of any desired strength. A second distinction between the two telephones is this. With the Bell apparatus the very weak electric impulses generated by the vibration of the transmitting diaphragm pass over the entire line to the receiving end, and in consequence the possible length of line is limited to a few miles, even under ideal conditions. With Edison's telephone the battery current does not flow on the main line, but passes through the primary circuit of an induction coil, from the secondary of which corresponding impulses of enormously higher potential are sent out on the main line to the receiving end. In consequence the line may be hundreds of miles in length. No modern telephone system is in use today that does not use these characteristic features, the varying resistance and the induction coil. The system inaugurated by Edison is shown by the diagram, Figure 3, in which the carbon transmitter, the induction coil, the line, and the distant receiver are respectively indicated. In Figure 4 an early form of the Edison carbon transmitter is represented in a sectional view. The carbon disc is represented by the black portion E near the diaphragm A, placed between two platinum plates D and G, which are connected in the battery circuit as shown by the lines. A small piece of rubber tubing B is attached to the center of the metallic diaphragm and presses lightly against an ivory piece F, which is placed directly over one of the platinum plates. Whenever therefore any motion is given to the diaphragm it is immediately followed by a corresponding pressure upon the carbon and by a change of resistance in the ladder as described above. It is interesting to note the position which Edison occupies in the telephone art from a legal standpoint. To this end the reader's attention is called to a few extracts from a decision of Judge Brown in two suits brought in the United States Circuit Court, District of Massachusetts by the American Bell Telephone Company against the National Telephone Manufacturing Company A.L. and Century Telephone Company A.L. reported in Federal Reporter 109, page 976, a sec. These suits were brought on the Burliner patent, which, it was claimed, covered broadly the electrical transmission of speech by variations of pressure between opposing electrodes in constant contact. The Burliner patent was declared invalid, and in the course of a long and exhaustive opinion in which the state of art and the work of Bell, Edison, Burliner, and others was fully discussed, the learned judge made the following remarks. The carbon electrode was the invention of Edison. Edison preceded Burliner in the transmission of speech. The carbon transmitter was an experimental invention of a very high order of merit. Edison, by countless experiments, succeeded in advancing the art. That Edison did produce speech with solid electrodes before Burliner is clearly proven. The use of carbon in a transmitter is, beyond controversy, the invention of Edison. Edison was the first to make apparatus in which carbon was used as one of the electrodes. The carbon transmitter, displaced Bell's magnetic transmitter, and under several forms of construction, remained the only commercial instrument. The advance in the art was due to the carbon electrode of Edison. It is conceded that the Edison transmitter as apparatus is a very important invention. An immense amount of painstaking and highly ingenious experiment preceded Edison's successful result. The discovery of the availability of carbon was unquestionably invention, and it resulted in the first practical success in the art. And of Appendix 6. And remarkable device is one of Edison's many inventions not generally known to the public at large, chiefly because the range of its application has been limited to the higher branches of science. He never applied for a patent on the instrument, but dedicated it to the public. The device was primarily intended for use in detecting and measuring infinitesimal degrees of temperature, however remote, and its conception followed Edison's researches on the carbon-telephone transmitter. Its principle depends on the variable resistance of carbon in accordance with a degree of pressure to which it is subjected. By means of this instrument, pressures that are otherwise inappreciable and undiscoverable may be observed and indicated. The detection of small variations of temperatures is brought about through the changes which heat or cold would produce and a sensitive material placed in contact with a carbon button, which is put in circuit with a battery and a delicate galvanometer. In the sketch, figure one, there is illustrated partly in section, the form of the transmitter which Edison took with him to Rollins, Wyoming in July 1878 on the expedition to observe the totally eclipse of the sun. The substance on whose expansion the working of the instrument depends is a strip of some material extremely sensitive to heat, such as vulcanite, shown at A, and firmly clamped at B. Its lower end fits into a slot in a metal plate, C, which in turn rests upon a carbon button. This ladder and the metal plate are connected in an electric circuit, which includes a battery and a sensitive galvanometer. A vulcanite or other strip is easily affected by differences of temperature, expanding and contracting by reason of the minutest changes. Thus an infinitesimal variation in its length through expansion or contraction changes the pressure on the carbon and affects the resistance of the circuit to a corresponding degree, thereby causing a deflection of the galvanometer, a movement of the needle in one direction denoting expansion and in the other contraction. The strip, A, is first put under a slight pressure, deflecting the needle a few degrees from zero. Any subsequent expansion or contraction of the strip may readily be noted by further movements of the needle. In practice, and for measurements of a very delicate nature, the decimeter is inserted in one arm of a wheat stone bridge, as shown at A in the diagram, figure two. The galvanometer is shown at B in the bridge wire, and at C, D, and E there are shown the resistances in other arms of the bridge, which are adjusted to equal the resistance of the decimeter circuit. The battery is shown at F. This arrangement tends to obviate any misleading deflections that might arise through changes in the battery. The dial on the front of the instrument is intended to indicate the exact amount of physical expansion or contraction of the strip. This is ascertained by means of a micrometer screw, S, which moves a needle, T, in front of the dial. This screw engages with the second and similar screw, which is so arranged as to move the strip of volcanite up or down. After a galvanometer deflection has been obtained through the expansion or contraction of the strip by reason of a change of temperature, a similar deflection is obtained mechanically by turning the screw, S, one way or the other. This causes the volcanite strip to press more or less upon the carbon button, and thus produces the desired change in the resistance of the circuit. When the galvanometer shows the desired deflection, the needle, T, will indicate upon the dial, in decimal fractions of an inch, the exact distance through which the strip has been moved. With such an instrument as the above, Edison demonstrated the existence of heat in the corona at the above mentioned total eclipse of the sun. But exact determinations could not be made at that time, because the tessemometer adjustment was too delicate, and at the best the galvanometer deflections were so marked that they could not be kept within the limits of the scale. The sensitiveness of the instrument may be easily comprehended when it is stated that the heat of the hand 30 feet away from the cone-like funnel of the tessemometer will so affect the galvanometer as to cause the spot of light to leave the scale. This instrument can also be used to indicate minute changes of moisture in the air by substituting a strip of gelatin in place of the volcanite. When so arranged, a moistened piece of paper held several feet away will cause a minute expansion of the gelatin strip, which affects the pressure on the carbon, and causes a variation in the circuit sufficient to throw the spot of light from the galvanometer mirror off the scale. The tessemometer has been used to demonstrate heat from remote stars, suns, such as Arcturus. End of Appendix 7 Appendix 8 The first patent that was ever granted on a device for permanently recording the human voice and other sounds, and for reproducing the same audibly at any future time, was United States Patent Number 200251 issued to Thomas A. Edison on February 19, 1878. The application, having been filed December 24, 1877, it is worthy of note that no references whatever were cited against the application while under examination in the patent office. This invention therefore marked the very beginning of an entirely new art, which, with the new industries attendant upon its development, has since grown to occupy a position of worldwide reputation. That the invention was of a truly fundamental character is also evident from the fact that although all talking machines of today differ very widely in refinement from the first crude but successful phonograph of Edison, their performance is absolutely dependent upon the employment of the principles stated by him in his patent number 200251. Quoting from this specification, attached to this patent, we find that Edison said, It will be at once obvious that these words describe perfectly the basic principle of every modern phonograph or other talking machine, irrespective of its manufacturer or trade name. Edison's first model of the phonograph is shown in the following illustration. It consisted of a metallic cylinder having a helical indenting groove cut upon it from end to end. This cylinder was mounted on a shaft supported on two standards. This shaft at one end was fitted with a handle by means of which the cylinder was rotated. There were two diaphragms, one on each side of the cylinder, one for being recorded and the other for reproducing speech or other sounds. Each diaphragm had attached to it a needle. By means of the needle, attached to the recording diaphragm, indentations were made in a sheet of tin foil stretched over the peripheral surface of the cylinder when the diaphragm was vibrated by reason of speech or other sounds. The needle on the other diaphragm subsequently followed these indentations, thus reproducing the original sounds. Crude, as this first model appears in comparison with machines of later development and refinement, it embodied their fundamental essentials and was in fact a complete practical phonograph from the first moment of its operation. The next step toward the evolution of the improved phonograph of today was another form of tin foil machine as seen in the illustration. It will be noted that this was merely an elaborate form of the first model and embodied several mechanical modifications, among which was the employment of only one diaphragm for recording and reproducing. Such was the general type of phonograph used for exhibition purposes in America and other countries in the three or four years immediately succeeding the date of this invention. In operating the machine the recording diaphragm was advanced nearly to the cylinder so that as the diaphragm was vibrated by the voice the needle would prick or indent a wave-like record in the tin foil that was on the cylinder. The cylinder was constantly turned during the recording and in turning was simultaneously moved forward. Thus the record would be formed on the tin foil in a continuous spiral line. To reproduce this record it was only necessary to again start at the beginning and cause the needle to retrace its path in the spiral line. The needle, in passing rapidly in contact with the recorded waves, was vibrated up and down causing corresponding vibrations of the diaphragm. In this way sound waves similar to those caused by the original sounds would be set up in the air, thus reproducing the original speech. The modern phonograph operates in a precisely similar way, the only difference being details of refinement. Instead of tin foil a wax cylinder is employed, the record being cut there on by a cutting tool attached to a diaphragm while the reproduction is affected by a means of a blunt stylus similarly attached. The cutting tool and stylus are devices made of sapphire, a gem next in hardness to a diamond, and they have to be cut and formed to an exact nicety by means of diamond dust, most of the work being performed at a high-powered microscope. The minute proportions of these devices will be apparent by a glance at the accompanying illustrations in which the object on the left represents a common pin and the object on the right the cutting tool and reproducing stylus, all actual sizes. In the next illustration, figure four, there is shown in the upper sketch greatly magnified the cutting or recording tool in the act of forming the record, being vibrated rapidly by the diaphragm and in the lower sketch similarly enlarged a representation of the stylus travelling over the record, thus made, in the act of affecting a reproduction. From the late summer of 1878 and to the fall of 1887 Edison was intensely busy on the electric light, electric railway and other problems, and virtually gave no attention to the phonograph. Hence, just prior to the latter named period, the instrument was still in its tin foil age, but he then began to devote serious attention to the development of an improved type that should be of greater commercial importance. The practical results are too well known to call for further comment, that his efforts were not limited in extent may be inferred from the fact that since the fall of 1887 to the present writing he has been granted in the United States 104 patents relating to the phonograph and its accessories. Interesting as the numerous inventions are, it would be a work of super-irrigation to digest all these patents in the present pages, as they would represent not only the inception but also the gradual development and growth of the wax record type of phonograph from its infancy to its present perfected machine, and records now so widely known all over the world. From among these many inventions, however, we will select two or three as examples of ingenuity and importance in their bearing upon present perfection of results. One of the difficulties of reproduction for many years was the trouble experienced in keeping the stylus in perfect engagement with the wave-like record so that every minute vibration would be reproduced. It should be remembered that the deepest cut of the recording tool is only about one-third the thickness of tissue paper. Hence it will be quite apparent that the slightest inequality in the surface of the wax would be sufficient to cause false vibration and thus give rise to distorted effects in such music or other sounds as were being reproduced. To remedy this Edison added an attachment which is called a floating weight and is shown at A in the illustration above. The function of the floating weight is to automatically keep the stylus in close engagement with the record, thus ensuring accuracy of reproduction. The weight presses the stylus to its work, but because of its mass cannot respond to the extremely rapid vibrations of the stylus. They are therefore communicated to the diaphragm. Some of Edison's most remarkable inventions are revealed in a number of interesting patterns relating to the duplication of phonograph records. It would be obviously impossible from a commercial standpoint to obtain a musical record from a high-class artist and sell such an original to the public as its cost might be from one hundred to several thousand dollars. Consequently it is necessary to provide some way by which duplicates be made cheaply enough to permit their purchase by the public at a reasonable price. The making of a perfect original musical or other record is a matter of no small difficulty as it requires special technical knowledge and skill gathered from many years of actual experience. But in the exact copying or duplication of such a record with its millions of microscopic waves and sub-waves the difficulties are enormously increased. The duplicates must be microscopically identical with the original. They must be free from false vibrations or other defects, although both original and duplicates are of such easily defacable material as wax, and the process must be cheap and commercial, not a scientific laboratory possibility. For making duplicates it was obviously necessary to first secure a mould carrying the record in negative or reversed form. From this could be moulded or cast positive copies which would be identical with the original. While the art of electroplating would naturally suggest itself as the means of making such a mould, an apparently insurmountable obstacle appeared on the very threshold. Wax being a nonconductor cannot be electroplated unless a conducting surface be first applied. The coatings ordinarily used in electro deposition were entirely out of the question on account of coarseness, the deep waves of the record being less than one thousandth of an inch in depth, and many of them probably ten to one hundred times as shallow. Edison finally decided to apply a preliminary metallic coating of infinitesimal thinness and accomplish this object by a remarkable process known as the vacuous deposit. With this he applied to the original record a film of gold, probably no thicker than one three hundred thousandths of an inch, or several hundred times less than the depth of an average wave. Three hundred such layers placed one on top of the other would make a sheet no thicker than tissue paper. The process consists in placing in a vacuum two leaves or electrodes of gold and between them the original record. A constant discharge of electricity of high tension between the electrodes is effected by means of an induction coil. The metal is vaporized by this discharge and is carried by it directly toward and deposited upon the original record, thus forming the minute film of gold above mentioned. The record is constantly rotated until its entire surface is coated. A sectional diagram of the apparatus, figure six, will aid to a clearer understanding of this ingenious process. After the gold film is formed in the manner described above, a heavy backing of baser metal is electroplated upon it, thus forming a substantial mold from which the original record is extracted by breakage or shrinkage. Duplicate records in any quantity may now be made from this mold by surrounding it with a cold water jacket and dipping it in a molten wax-like material. This congeals on the record's surface just as melted butter would collect on a cold knife, and when the mold is removed the surplus wax falls out, leaving a heavy deposit of the material which forms the duplicate record. Numerous ingenious inventions have been made by Edison, providing for a variety of rapid and economical methods of duplication, including methods of shrinking a newly made copy to facilitate its quick removal from the mold. Methods of reaming, of forming ribs on the interior, and for many other important and essential details which limits of space will not permit of elaboration. Those mentioned above are but fair examples of the persistent and effective work he has done to bring the phonograph to its present state of perfection. In Perusing chapter 10 of the foregoing narrative the reader undoubtedly noted Edison's clear apprehension of the practical uses of the phonograph as evidenced by his prophetic utterances in the article written by him for the North American Review in June 1878. In view of the crudity of the instrument at that time it must be acknowledged that Edison's foresight as vindicated by later events was most remarkable. This remarkable was his intensely practical grasp of mechanical possibilities of future types of the machine. For we find in one of his early patents, number 1644 of 1878, the disc form of phonograph which, some ten to fifteen years later, was supposed to be a new development in the art. This disc form was also covered by Edison's application for a United States patent filed in 1879. This application met with some merely minor technical objections in the patent office, and seems to have passed into the abandoned class for want of prosecution. Probably because of being overlooked in the tremendous pressure arising from his development of his electric lighting system. End of Appendix 8 Although Edison's contributions to human comfort and progress are extensive in number and extraordinarily vast and comprehensive in scope and variety, the universal verdict of the world points to his incandescent lamp and system of distribution of electrical current as the central and crowning achievements of his life up to this time. This view would seem entirely justifiable when we consider the wonderful changes in the conditions of modern life that have been brought about by the widespread employment of these inventions and the gigantic industries that have grown up and been nourished by their worldwide application. That he was in this instance a true pioneer and creator is evident as we consider the subject for the United States patent number 223898, issued to Edison on January 27th, 1880 for an incandescent lamp was of such fundamental character that it opened up an entirely new and tremendously important art, the art of incandescent electric lighting. This statement cannot be successfully controverted, for it has been abundantly verified after many years of costly litigation. If further proof were desired, it is only necessary to point to the fact that after 30 years of most strenuous and practical application in the art by the keenest intellects in the world, every incandescent lamp that has ever since been made, including those of modern days, is still dependent upon the employment of the essentials disclosed in the above named patent, namely, a filament of high resistance enclosed in a sealed glass globe exhausted of air with conducting wires passing through the glass. The incandescent lamp is such a simple appearing article, merely a filament sealed in a glass globe, that its intrinsic relation to the art of electric lighting is far from being apparent at sight. To the lay mind it would seem that this must have been the obvious device to make in order to obtain electric light by incandescence of carbon or other material, but the reader has already learned from the preceding narrative that prior to its invention by Edison such a device was not obvious, even to the most highly trained experts of the world at that period. Indeed, it was so far from being obvious that for some time after he had completed practical lamps and was actually lighting them up 24 hours a day, such a device and such a result were declared by these same experts to be an utter impossibility. For a short while the world outside of Menlo Park held Edison's claims in derision. His lamp was pronounced a fake, a myth, possibly a momentary success magnified to the dignity of a permanent device by an over-enthusiastic inventor. Such criticism, however, did not disturb Edison. He knew that he had reached the goal. Long ago, by a close process of reasoning, he had clearly seen that the only road to it was through the path he had traveled, and which was now embodied in the philosophy of his incandescent lamp, namely a filament or carbon of high resistance and small radiating surface sealed into a glass globe exhausted of air to a high degree of vacuum. In originally committing himself to this line of investigation, he was well aware that he was going in a direction diametrically opposed to that followed by previous investigators. Their efforts had been confined to low resistance burners of large radiating surface for their lamps, but he realized the utter futility of such devices. The tremendous problems of heat and the prohibitive quantities of copper that would have been required for conductors of such lamps would be absolutely out of the question in commercial practice. He was convinced from the first that the true solution of the problem lay in a lamp which should have as its illuminating body a strip of material which would offer such a resistance to the flow of electric current that it could be raised to a high temperature, incandescence, and be of such small cross-section that it would radiate but little heat. At the same time, such a lamp must require a relatively small amount of current in order that comparatively small conductors could be used, and its burner must be capable of withstanding the necessarily high temperatures without disintegration. It is interesting to note that these conceptions were in Edison's mind in an early period of his investigations, when the best expert opinion was that the subdivision of the electric current was an igneous fetus. Hence we quote the following notes he made, November 15, 1878, in one of the laboratory notebooks. A given straight wire having one ohm resistance and certain length is brought to a given degree of temperature by given battery. If the same wire be coiled in such a manner that but one quarter of its surface radiates, its temperature will be increased four times with the same battery, or one quarter of this battery will bring it to the temperature of straight wire, or the same given battery will bring a wire whose total resistance is four ohms to the same temperature as straight wire. This was actually determined by trial. The amount of heat lost by a body is in proportion to the radiating surface of that body. If one square inch of platina be heated to 100 degrees, it will fall to say zero in one second, whereas if it was at 200 degrees it would require two seconds. Hence, in the case of incandescent conductors, if the radiating surface be 12 inches and the temperature on each inch be 100 or 1200 for all, if it is so coiled or arranged that there is what one quarter or three inches of radiating surface, then the temperature on each inch will be 400. If reduced to three quarters of an inch, it will have on that three quarters of an inch 1600 degrees Fahrenheit. Notwithstanding, the original total amount was about 1200, because the radiation has been reduced to three quarters or 75 units. Hence, the effect of the lessening of the radiation is to raise the temperature of each remaining inch not radiating to 125 degrees. If the radiating surface should be reduced to 33 seconds of an inch, the temperature would reach 6400 degrees Fahrenheit. To carry out this law to the best advantage in regard to platina, etc. Then with a given length of wire to quadruple the heat, we must lessen the radiating surface to one quarter. And to do this in a spiral, three quarters must be within the spiral and one quarter outside for radiating. Hence, a square wire or other means, such as a spiral within a spiral must be used. These results account for the enormous temperatures of the electric arc with one horsepower. As for instance, if one horsepower will heat 12 inches of wire to 1000 degrees Fahrenheit, and this is concentrated to have one quarter of the radiating surface, it would reach a temperature of 4000 degrees or sufficient to melt it. But supposing it infusible, the further concentration to one eighth its surface, it would reach a temperature of 16000 degrees, and to one 32nd its surface, which would be about the radiating surface of the electric arc, it would reach 64000 degrees Fahrenheit. Of course, when light is radiated in great quantities, not quite these temperatures would be reached. Another curious law is this. It will require a greater initial battery to bring an iron wire of the same size and resistance to a given temperature than it will a platinum wire in proportion to their specific heats. And in the case of carbon, a piece of carbon three inches long and one eighth diameter, with a resistance of one ohm, will require a greater battery power to bring it to a given temperature than a cylinder of thin platinum foil of the same length, diameter, and resistance, because the specific heat of carbon is many times greater. Besides, if I am not mistaken, the radiation of a roughened body for heat is greater than a polished one like platinum. Proceeding logically upon these lines of thought, and following them out through many ramifications, we have seen how he at length made a filament of carbon of high resistance and small radiating surface, and through a concurrent investigation of the phenomena of high vacua and occluded gases, was able to produce a true incandescent lamp. Not only was it a lamp as a mere article, a device to give light, but it was also an integral part of his great and complete structure of lighting, to every part of which it bore a fixed and definite ratio, and in relation to which it was the keystone that held the structure firmly in place. The work of Edison on incandescent lamps did not stop at this fundamental invention, but extended through more than 18 years of a most intense portion of his busy life. During that period, he was granted 149 other patents on the lamp and its manufacturer. Although very many of these inventions were of the utmost importance and value, we cannot attempt to offer a detailed exposition of them in this necessarily brief article, but must refer the reader, if interested, to the patents themselves, a full list being given at the end of this appendix. The outline sketch will indicate the principal patents covering the basic features of the lamp. The litigation on the Edison lamp patents was one of the most determined and stubbornly fought contests in the history of modern jurisprudence. Vast interests were at stake. All of the technical, expert, and professional skill and knowledge that money could procure or experience devise were availed of in the bitter fights that raged in the courts for many years. And although the Edison interests had spent from first to last nearly $2 million, and had only about three years left in the life of the fundamental patent, Edison was thoroughly sustained as to priority by the decisions in the various suits. We shall offer a few brief extracts from some of these decisions. In a suit against the United States Lighting Company, United States Circuit Court for the Southern District of New York, July 14, 1891, Judge Wallace said, in his opinion, the futility of hoping to maintain a burner in vacuo with any permanency had discouraged prior inventors, and Mr. Edison is entitled to the credit of obviating the mechanical difficulties which dishearted them. He was the first to make a carbon of materials, and by a process which was especially designed to impart high specific resistance to it, the first to make a carbon in a special form for the special purpose of imparting to it high total resistance, and the first to combine such a burner with the necessary adjuncts of lamp construction to prevent its disintegration and give it sufficiently long life. By doing these things he made a lamp which was practically operative and successful, the embryo of the best lamps now in commercial use. And but for the subdivision of the electric light by incandescence would still be nothing but the igneous fatus which it was proclaimed to be in 1879 by some of the reamed experts who are now witnesses to belittle his achievement and show that it did not rise to the dignity of an invention. It is impossible to resist the conclusion that the invention of the slender thread of carbon as a substitute for the burners previously employed opened the path to the practical subdivision of the electric light. An appeal was taken in the above suit to the United States Circuit Court of Appeals, and on October 4th, 1892 the decree of the lower court was affirmed. The judges, Lake Home and Shipman, in a long opinion reviewed the facts and the art and said, inter alia, Edison's invention was practically made when he ascertained the therefore unknown fact that carbon would stand high temperature, even when very attenuated, if operated in a high vacuum, without the phenomenon of disintegration. This fact he utilized by the means which he has described, a lamp having a filamentary carbon burner in a nearly perfect vacuum. In a suit against the Boston incandescent lamp company at all, in the United States Circuit Court for the District of Massachusetts, decided in favor of Edison on June 11th, 1894, Judge Colt, in his opinion, said, among other things, Edison made an important invention. He produced the first practical incandescent electric lamp. The patent is a pioneer in the sense of the patent law. It may be said that his invention created the art of incandescent electric lighting. Opinions of other courts, similar in tenor to the foregoing, may be cited, but it would be merely in the nature of reiteration. The above are sufficient to illustrate the direct clearness of judicial decision on Edison's position as the founder of the art of electric lighting by incandescence. End of Appendix 9 Recording by Jerome Lawson