CHAPTER XXIX. The title of this chapter might imply that there is an unsocial side to Edison. In a sense, this is true, for no one is more impatient or intolerant of an eruption when deeply engaged in some line of experiment. Then the caller, no matter how important or what his mission, is likely to realize his utter insignificance and be sent away without accomplishing his object. But, generally speaking, Edison is easy tolerance itself, with a peculiar weakness toward those who have had the least right to make any demands on his time. Man is a social animal, and that describes Edison, but it does not describe accurately the inventor asking to be let alone. Edison never sought society, but society has never ceased to seek him. And today, as ever, the pressure upon him to give up his work and receive honors, meet distinguished people, or attend public functions is intense. Only two or three years ago, a flattering invitation came from one of the great English universities to receive a degree, but at that moment he was deep in experiments on his new storage battery, and nothing could budge him. He would not drop the work, and while highly appreciative of the proposed honor, let it go by rather than quit for a week or two the stern drudgery of probing for the fact and the truth. Whether one approves or not, it is at least admirable stoicism, of which the world has too little. A similar instance is that of a visit paid to the laboratory by someone bringing a gold medal from a foreign society. It was a very hot day in summer, the visitor was in full social regalia of silk hat and frock coat, and insisted that he could deliver the medal only into Edison's hands. At that moment, Edison stripped pretty nearly down to the buff, was at the very crisis of an important experiment, and refused absolutely to be interrupted. He had neither sought nor expected the medal, and if the delegate didn't care to leave it, he could take it away. And last Edison was over persuaded, and all dirty and perspiring as he was, received the medal rather than caused the visitor to come again. On one occasion, receiving a medal in New York, Edison forgot it on the ferry boat and left it behind him. A few years ago, when Edison had received the Albert Medal of the Royal Society of Arts, one of the present authors called at the laboratory to see it. Nobody knew where it was, hours passed before it could be found, and when at last the accompanying letter was produced, it had an office date stamped right over the signature of the royal president. A visitor to the laboratory with one of these medallic awards asked Edison if he had any others. Oh, yes, he said. I have a couple of quarts more up at the house. All this sounds like lack of appreciation, but it is anything else than that. While in Paris in 1889, he wore the decoration of the Legion of Honor whenever occasion required, but at all other times turned the badge under his lapel because he hated to have fellow Americans think he was showing off. And anyone who knows Edison will bear testimony to his utter absence of ostentation. It may be added that, in addition to the two quarts and medals up at the house, there will be found at Glenmont many other signal tokens of esteem and goodwill. A beautiful cigar case from the late Tsar of Russia, bronzes from the government of Japan, steel trophies from Krop, and a host of other memenos to one of which he thus refers, when the experiments with the light were going on at Menlo Park, Sarah Bernhardt came to America. One evening, Robert L. Cutting of New York brought her out to see the light. She was a terrific rubber neck. She jumped all over the machinery, and I had one man especially to guard her dress. She wanted to know everything. She would speak in French and cutting would translate into English. She stayed there about an hour and a half. Bernhardt gave me two pictures painted by herself, which she sent me from Paris. Reference has already been made to the collars upon Edison, and to give simply the names of persons of distinction would fill many pages of this record. Some were mere consumers of time. Others were gladly welcomed, like Lord Kelvin, the greatest physicist of the last century, with whom Edison was always in friendly communication. The first time I saw Lord Kelvin, he came to my laboratory at Menlo Park in 1876. He reported most favorably on Edison's automatic telegraph system at the Philadelphia Exposition of 1876. I was then experimenting with sending eight messages simultaneously over a wire by means of synchronizing tuning forks. I would take a wire with similar apparatus at both ends, and would throw it over on one set of instruments, take it away, and get it back so quickly that you would not miss it, thereby taking advantage of the rapidity of electricity to perform operations. On my local wire, I got it to work very nicely. When Sir William Thompson Kelvin came in the room, he was introduced to me and had a number of friends with him. He said, What have you here? I told him briefly what it was. He then turned around and to my great surprise explained the whole thing to his friends. Quite a different exhibition was given two weeks later by another well-known Englishman, also an electrician, who came in with his friends, and I was trying for two hours to explain it to him and failed. After the introduction of the electric light, Edison was more than ever in demand socially, but he shunned functions like the plague not only because of the serious interference with work, but because of his deafness. Some dinners he had to attend, but a man who ate little and heard less could derive practically no pleasure from them. George Washington Childs was very anxious I should go down to Philadelphia to dine with him. I seldom went to dinners. He insisted I should go that a special car would leave New York. It was for me to meet Mr. Joseph Chamberlain. We had the private car of Mr. Roberts, president of the Pennsylvania Railroad. We had one of those celebrated dinners that only Mr. Childs could give, and I heard speeches from Charles Francis Adams and different people. When I came back to the depot, Mr. Roberts was there and insisted on carrying my satchel for me. I never could understand that. Among the more distinguished visitors of the electric lighting period was President Diaz, with whom Edison became quite intimate. President Diaz of Mexico visited this country with Mrs. Diaz, a highly educated and beautiful woman. She spoke very good English. They both took a deep interest in all they saw. I don't know how it ever came about. Edison's not my line, but I seem to be delegated to show them around. I took them to railroad buildings, electric light plants, fire departments, and showed them a great variety of things. It lasted two days. Of another visit Edison says, sitting bull and 15 suit Indians came to Washington to see the great father and then to New York and went to the Garrick Street Works. We could make some very good pyrotechnics there, so we determined to give the Indians a scare, but it didn't work. We had an arc there of a most terrifying character, but they never moved a muscle. Another episode at Garrick Street did not find the visitors quite so stoical. In testing dynamos at Garrick Street we had a long flat belt running parallel with the floor about four inches above it and traveling 4000 feet a minute. One day one of the directors brought in three or four ladies to the works to see the new electric light system. One of the ladies had a little poodle led by a string. The belt was running so smoothly and evenly the poodle did not notice the difference between it and the floor and got into the belt before we could do anything.  A very interesting period on the social side was the visit paid by Edison and his family to Europe in 1889 when he had made a splendid exhibit of his inventions and apparatus at the Great Paris Centennial Exposition of that year to the extreme delight of the French who welcomed him with open arms. The political sentiments that the exposition celebrated were not as to find general sympathy and monarchical Europe so that the crowned heads were conspicuous by their absence. It was not of course by way of theatrical antithesis that Edison appeared in Paris at such a time but the contrast was nonetheless striking and effective. It was felt that after all that which the great exposition exemplified at its best the triumph of genius over matter over ignorance over superstition met with its due recognition when Edison came to participate and to felicitate a noble nation that could show so much in the victories of civilization and the arts despite its long trials and its long struggle for liberty. It is no exaggeration to say that Edison was greeted with the enthusiastic homage of the whole French people. They could find no praise warm enough for the man who had organized the echoes and tamed the lightning and whose career was so picturesque with eventful and romantic development. In fact for weeks together it seemed as though no Parisian paper was considered complete and up to date without an article on Edison. The exuberant wit and fancy of the feliteness seized upon his various inventions evolving from them others of the most extraordinary nature with which to bedazzle and bewilder the reader. At the close of the exposition Edison was created a commander of the Legion of Honor. His own exhibit made at a personal expense of over 100,000 dollars covered several thousand square feet in the vast machinery hall and was centered around a huge Edison lamp built of myriads of smaller lamps of the ordinary size. The great attraction however was the display of the perfected phonograph. Several instruments were provided and every day all day long while the exposition lasted cues of eager visitors from every quarter of the globe were waiting to hear the little machine talk and sing and reproduce their own voices. Never before was such a collection of the languages of the world made. It was the first linguistic concourse since babble times. We must let Edison tell the story of some of his experiences. At the Universal Exposition at Paris in 1889 I made a personal exhibit covering about an acre. As I had no intention of offering to sell anything I was showing and was pushing no companies. The whole exhibition was made for honor and without any hope of profit. But the Paris newspapers came around and wanted pay for notices of it, which we promptly refused. Whereupon there was a rather a stormy time for a while but nothing was published about it. While at the exposition I visited the opera house. The president of France lent me his private box. The opera house was one of the first to be lighted by the incandescent lamp and the managers took great pleasure in showing me down through the labyrinth containing the wiring, dynamos, etc. When I came into the box the orchestra played the star-spangled banner and all the people in the house arose whereupon I was very much embarrassed. After I had been an hour at the play the manager came around and asked me to go underneath the stage as they were putting on a ballet of 300 girls, the finest ballet in Europe. It seems there is a little hole in the stage with a hood over it, in which the prompter sits when opera is given. In this instance it was not occupied and I was given the position in the prompter's seat and saw the whole ballet at close range. The city of Paris gave me a dinner at the new Hotel de Ville, which was also lighted with Edison system. They had a very fine installation of machinery. As I could not understand or speak a word of French, I went to see our minister, Mr. Whitelaw Reed, and got him to send a deputy to answer for me, which he did with my grateful thanks. Then the telephone company gave me a dinner, and the engineers of France, and I attended the dinner celebrating the 50th anniversary of the discovery of photography. Then they sent to read my decoration and they tried to put a sash on me, but I could not stand for that. My wife had me wear the little red button, but when I saw Americans coming, I would slip it out of my lapel, as I thought they would jolly me for wearing it. Nor was this all. Edison naturally met many of the celebrities of France. I visited the Eiffel Tower at the invitation of Eiffel. We went to the top, where there was an extension and a small place in which Eiffel's private office. In this was a piano. When my wife and I arrived at the top, we found that Gounod, the composer, was there. We stayed a couple of hours and Gounod sang and played for us. We spent a day at Moudon, an old palace given by the government to Janssen, the astronomer. He occupied three rooms and there were 300. He had the grand dining room for his laboratory. He showed me a gyroscope he had got up, which made the incredible number of 4,000 revolutions in a second. A modification of this was afterward used on the French Atlantic lines for making an artificial horizon to take observations for position at sea. In connection with this, a gentleman came to me a number of years afterward, and I got out a part of some plans for him.  He wanted the gyroscope to keep platform perfectly horizontal no matter how rough the sea was. Upon this platform he was going to mount a telescope to observe an eclipse off the Gold Coast of Africa, but for some reason it was never completed. Pasteur invited me to come down to the institute, and I went and had quite a chat with him. I saw a large number of persons being inoculated, and also the whole modus operandi, which was very interesting. I saw one beautiful boy of about ten, the son of an English lord. His father was with him. He had been bitten in the face and was taking the treatment. I said to Pasteur, will he live? No, said he. The boy will be dead in six days. He was bitten too near the top of the spinal column and came too late. Edison has no opinion to offer as an expert on art, but has his own standard of taste. Of course I visited the Louvre and saw the old masters, which I could not enjoy. And I attended the Luxembourg with modern masters, which I enjoyed greatly. To my mind, the old masters are not art, and I suspect that many others are of the same opinion, and that their value is in their scarcity and in the variety of men with lots of money. Someone akin to this is a shrewd comment on one feature of the exposition. I spent several days in the exposition at Paris. I remember going to the exhibit of the Kimberly Diamond mines, and they kindly permitted me to take diamonds from some of the blue earth, which they were washing by machinery to exhibit the mine operations. I found several beautiful diamonds, but they seemed a little lightweight to me when I was picking them out. They were diamonds for exhibition purposes, probably glass. This did not altogether complete the European trip of 1889, for Edison wished to see Helmholtz. After leaving Paris, we went to Berlin. The French papers then came out and attacked me because I went to Germany, and said I was now going over to the enemy. I visited all the things of interest in Berlin, and then on my way home I went with Helmholtz and Siemens in a private compartment to the meeting of the German Association of Science at Heidelberg, and spent two days there. When I started from Berlin on the trip, I began to tell American stories. Siemens was very fond of these stories and would laugh immensely at them and could see the points and the humor by his imagination. But Helmholtz could not see one of them. Siemens would quickly in German explain the point, but Helmholtz could not see it, although he understood English, which Siemens could speak. Still the explanations were made in German. I always wished I could have understood Siemens explanations of the points of these stories. At Heidelberg, my assistant, Mr. Wangenmann, an accomplished German American, showed the phonograph before the Association. Then came the trip from the continent to England, of which this will certainly pass as a graphic picture. When I crossed over to England, I had heard a good deal about the terrors of the English Channel as regards seasickness. I had been over the ocean three times and did not know what seasickness was so far as I was concerned myself. I was told that while a man might not get seasick on the ocean, if he met a good storm on the Channel, it would do for him. When we arrived at the Calais to cross over, everybody made for the restaurant. I did not care about eating and did not go to the restaurant, but my family did. I walked out and tried to find the boat. Going along the dock, I saw two small smokestacks sticking up and looking down saw a little boat. Where is the steamer that goes across the Channel? This is the boat. There had been a storm in the North Sea that had carried away some of the boats on the German steamer, and it certainly looked awful tough outside. I said to the man, would that boat live in that sea? Oh yes, he said, but we've had a bad storm.  The managing director of the English Railroad owning this line was Forbes, who heard I was coming over and placed the private saloon at my disposal. The moment my family got in the room with the French ladies made and the rest, they commenced to get sick, so I felt pretty sure I was in for it. We started out of the little inlet and got into the Channel, and that boat went in 17 directions simultaneously. I waited a while to see what was going to occur and then went into the smoking compartment. Nobody was there. By and by, the fun began. Sounds of all kinds and varieties were heard in every direction. They were all sick. There must have been 100 people aboard. I didn't see a single exception except the waiters and myself. I asked one of the waiters concerning the boat itself and was taken to see the engineer and went down to look at the engines and saw the captain. But I kept mostly in the smoking room.  The English Channel is a holy terror all right, but it didn't affect me. I must be out of balance. While in Paris, Edison had met Sir John Pender, the English Cable King, and had received an invitation from him to make a visit to his country residence. Sir John Pender, the master of the cable system of the world at that time, I met in Paris. I think he must have lived among a lot of people who were very solemn because I went out riding with him in the Bordeaux Belon and started in to tell him American stories. Although he was a Scotchman, he laughed immoderately. He had the faculty of understanding and quickly seen the points of the stories, and for three days after, I could not get rid of him. Finally, I made him a promise that I would go to his country house at Footscray, near London. So I went there and spent two or three days telling him stories. While at Footscray, I met some of the backers of Ferranti, then putting up a gigantic alternating current dynamo near London to send 10 or 15,000 votes up into the main district of the city for electric lighting. I think Pender was interested. At any rate, the people invited to dinner were very much interested, and they questioned me as to what I thought of the proposition. I said I hadn't any thought about it and could not give any opinion until I saw it. So I was taken up to London to see the dynamo in course of construction and the methods employed, and they insisted I should give them some expression of my views. While I gave them my opinion, it was reluctantly. I did not want to do so. I thought that commercially the thing was too ambitious, that Ferranti's ideas were too big just then, that he ought to have started a little smaller until he was sure. I understand that this installation was not commercially successful, as there were many great troubles before Ferranti had good ideas, and he was no small man. Incidentally, it may be noted here that during the same year, 1889, the various manufacturing Edison lighting interests in America were brought together under the leadership of Mr. Henry Vallard and consolidated in the Edison General Electric Company with a capital of no less than $12 million on an 8 percent dividend basis. The numerous Edison central stations all over the country represented much more than that sum and made a splendid outlet for the product of the factories. A few years later came the consolidation with the Thompson Houston interest in the General Electric Company, which under the brilliant and vigorous management of President C. A. Coffin has become one of the greatest manufacturing institutions of the country with an output of apparatus reaching towards $75 million annually. The net result of both financial operations was, however, to detach Edison from the special field of invention to which he had given so many of his most fruitful years, and to close very definitely that chapter of his life, leaving him free to develop other ideas and interests as set forth in these volumes. It might appear strange on the surface, but one of the reasons that most influenced Edison to regrets in connection with the big trade of 1889 was that it separated him from his old friend and ally, Bergman, who on selling out saw a great future for himself in Germany went there and realized it. Edison has always had an amused admiration for Bergman and his social side is often made evident by his love of telling stories about those days of struggle. Some of the stories were told for this volume. Bergman came to work for me as a boy, says Edison. He started in on stock quotation printers. As he was a rapid workman and paid no attention to the clock, I took a fancy to him and gave him peace work. He contrived so many little tools to cheapen the work that he made lots of money. I even helped him get up tools until it occurred to me that this was too rapid a process of getting rid of my money, as I hadn't the heart to cut the price when it was originally fair. After a year or so, Bergman got enough money to start a small shop in Worcester Street, New York, and it was at this shop that the first photographs were made for sale. Then came the carbon telephone transmitter, a large number which were made by Bergman for the Western Union. Finally came the electric light. A dynamo was installed in Bergman's shop to permit him to test the various small devices which he was then making for the system. He rented power from a Jew who owned the building. Power was supplied from a 50-horsepower engine to other tenants on the several floors. Soon after the introduction of the big dynamo machine, the landlord appeared in the shop and insisted that Bergman was using more power than he was paying for, and said that lately the belt on the engine was slipping and squealing. Bergman maintained that he must be mistaken. The landlord kept going among his tenants and finally discovered the dynamo. Oh, Mr. Bergman, now I know where my power goes to, pointing to the dynamo. Bergman gave him a weathering look of scorn and said, Come here and I will show you. Throwing off the belt and disconnecting the wires, he spun the armature around by hand. There, said Bergman, you see it's not here that you must look for your loss. This satisfied the landlord and he started off to his other tenants. He did not know that that machine, when the wires were connected, could stop his engine. Soon after, the business had grown so large that E.H. Johnson and I went in as partners and Bergman rented an immense factory building at the corner of Avenue B in East 17th Street, New York, six stories high and covering a quarter of a block. Here were made all the small things used on the electric lighting system, such as sockets, chandeliers, switches, meters, etc. In addition, stock tickers, telephones, telephone switchboards, and typewriters were made the Hammond typewriters were perfected and made there. Over 1500 men were finally employed. This shop was very successful both scientifically and financially. Bergman was a man of great executive ability and carried economy of manufacture to the limit. Among all the men I have had associated with me, he had the commercial instinct most highly developed. One need not wonder at Edison's reminiscent remark that in any trade any of my boys made with Bergman he always got the best of them no matter what it was. One time there was to be a convention of the managers of the Edison Illuminating companies at Chicago. There were a lot of representatives from the East and a private car was hired. At Jersey City a poker game was started by one of the delegates. Bergman was induced to enter the game. This was played right through to Chicago without any sleep but the boys didn't mind that. I had gotten them immune to it. Bergman had won all the money and when the porter came in and said, Chicago! Bergman jumped up and said, what? Chicago? I thought it was only Philadelphia. But perhaps this further story is a better indication of developed humor and shrewdness. A man by the name of Epstein had been in the habit of buying brass chips and trimmings from the Lays and in some way Bergman found out that he had been cheated. This hurt his pride and he determined to get even. One day Epstein appeared and said, good morning Mr. Bergman have you any chips today? No, said Bergman, I have none. That's strange Mr. Bergman won't you look? No he wouldn't look. He knew he had none. Finally Epstein was so persistent that Bergman called an assistant and told him to go and see if he had any chips. He returned and said they had the largest and finest lot they had ever seen. Epstein went up to the several boxes piled full of chips and so heavy that he could not lift even one end of the box. Now Mr. Bergman said Epstein how much for the lot? Epstein said Bergman you have cheated me and I will no longer sell by the lot but will sell only by the pound. No amount of argument would apparently change Bergman's determination to sell by the pound but finally Epstein got up to 250 dollars for the lot and Bergman appearing as if disgusted, accepted and made him count out the money. Then he said well Epstein goodbye I've got to go down to Wall Street. Epstein and his assistant then attempted to lift the boxes to carry them out but couldn't and then discovered that calculations as to quantity have been thrown out because the boxes had all been screwed down to the floor and mostly filled with boards with a veneer of brass chips. He made such a scene that he had to be removed by the police. I met him several days afterward and he said he had forgiven Mr. Bergman as he was such a smart businessman and the scheme was so ingenious. One day as a joke I filled three or four sheets of full scrap paper with a jumble of figures and told Bergman they were calculations showing the great loss of power from blowing the factory whistle. Bergman thought it would be real and never after that would he permit the whistle to blow. Another glimpse of the social side is afforded in the following little series of pen pictures of the same place and time. I had my laboratory at the top of the Bergman works after moving from Menlo Park. The building was six stories high. My father came there when he was eighty years of age. The old man had powerful lungs. In fact when I was examined by the Mutual Life Insurance Company in 1873 my lung expansion was taken by the doctor and the old gentleman was there at the time. He said to the doctor I wish you would take my lung expansion too. The doctor took it and his surprise is very great as it was one of the largest on record. I think it was five and one half inches. There were only three or four could beat it. Little Bergman hadn't much lung power. The old man said to him one day let's run upstairs. Bergman agreed and ran up. When they got there Bergman was all done up but my father never showed a sign of it. There was an elevator there and each day while it was traveling up I held the stem of my waterberry watch up against the column in the elevator shaft and it finished the winding by the time I got up the six stories. The original method of reducing the amount of physical labor involved in watch winding brings to mind another instance of shrewdness mentioned by Edison with regard to his newsboy days. Being asked whether he did not get imposed upon with bad bank bills he replied that he subscribed to a bank note detector and consulted it closely whenever a note of any size fell into his hands. He was then less than 14 years old. The conversations with Edison that elicited these stories brought out some details as to peril that attends experimentation. He has confronted many as serious physical risk and counts himself lucky to have come through without a scratch or scar. Four instances of personal danger may be noted in his own language. When I started at Menlo I had an electric furnace for welding rare metals that I did not know about very clearly. I was in the dark room where I had a lot of chloride of sulfur a very corrosive liquid. I did not know that it would decompose by water. I poured in a beaker full of water and the whole thing exploded and threw a lot of it into my eyes. I ran to the hydrant leaned over backward opened my eyes and ran the hydrant right into them but it was two weeks before I could see. The next time we just saved ourselves I was making some stuff to squirt into filaments for the incandescent lamp. I made about a pound of it. I had used ammonia and bromine. I did not know it at the time but I had made bromide of nitrogen. I put the large bulk of it in three filters and after it had been washed and all the water had come through the filter I opened the three filters and laid them on a hot steam plate to dry with the stuff. While I am Mr. Sadler one of my assistants were working near it there was a sudden flash of light and a very smart explosion. I said to Sadler what is that? I don't know he said and we paid no attention. In about half a minute there was a sharp concussion and Sadler said see it's that stuff on the steam plate. I grabbed the whole thing and threw it in the sink and poured water on it. I saved a little of it and found it was a terrific explosive. The reason why those little preliminary explosions took place was that a little had spattered out on the edge of the filter paper and had dried first and exploded. Had the main body exploded there would have been nothing left of the laboratory I was working in. At another time I had a bracheting machine for bracheting iron ore. I had a lever held down by our powerful spring and a rod one inch in diameter and four feet long. While I was experimenting with it and standing beside it a washer broke and that spring through the rod right up to the ceiling with a blast and it came down just within an inch of my nose and went clear through a two inch plank. That was within an inch of your life as they say. In my experimental plant for concentrating iron ore in the northern part of New Jersey we had a vertical dryer a column about nine feet square and eighty feet high. At the bottom there was a space where two men could go through a hole and then all the rest of the column was filled with baffle plates. One day this dryer got blocked and the ore would not run down so I and the vice president of the company Mr. Mallory crowded through the manhole to see why the ore would not come down. After we got in the ore did come down and there were fourteen tons of it above us. The men outside knew we were in there and they had a great time digging us out and getting air to us. Such incidents brought out in narration the fact that many of the men working with him had been less fortunate particularly those who had experimented with the Rintgen x-ray whose ravages like those of leprosy were responsible for the mutilation and death of at least one expert assistant. In the early days of work on the incandescent lamp also there was considerable trouble with mercury. I had a series of vacuum pumps worked by mercury and used for exhausting experimental incandescent lamps. The main pipe which is full of mercury was about seven and one half feet from the floor. Along the length of the pipe were outlets to which thick rubber tubing was connected each tube to a pump. One day while experimenting with the mercury pump my assistant an awkward country lad from a farm on Staten Island who had adenoids in his nose and breathe through his mouth which was always wide open was looking up at this pipe at a small leak of mercury when the rubber tube came off and probably two pounds of mercury went into his mouth and down his throat and got through his system somehow. In a short time he became salivated and his teeth got loose. He went home and shortly his mother appeared at the laboratory with a horse whip which she proposed to use on the proprietor. I was fortunately absent and she was modified somehow by my other assistants. I had given the boy the considerable iodide of potassium to prevent salivation but it did no good in this case. When the first lamp works were started at Menlo Park one of my experiments seemed to show that hot mercury gave a better vacuum in the lamp than cold mercury. I thereupon started to heat it. Soon all the men got salivated and things look serious but I found that in the mirror factories where mercury was used extensively the French government made the giving of iodide of potassium compulsory to prevent salivation. I carried out this idea and made every man take a dose every day. There was great opposition and hot mercury was finally abandoned. It will have been gathered that Edison has owed his special immunity from occupational diseases not only to luck but to unusual powers of endurance and a strong physique inherited no doubt from his father. Mr. Mallory mentions a little fact that bears on this exceptional quality of bodily powers. I have often been surprised at Edison's wonderful capacity for the instant visual perception of differences in materials that were invisible to others until he would patiently point them out. This had puzzled me for years but one day I was unexpectedly let into part of the secret. For some little time past Mr. Edison had noticed that he was bothered somewhat in reading print and I asked him to have an oculus give him reading glasses. He partially promised but never took time to attend to it. One day he and I were in the city and as Mrs. Edison had spoke to me about it and as we happened to have an hour to spare I persuaded him to go to an oculus with me. Using no names I asked the latter to examine the gentleman's eyes. He did so very conscientiously and it was an interesting experience for he was kept busy answering Mr. Edison's numerous questions. When the oculus finished he turned to me and said I have been many years in the business but have never seen an optic nerve like that of this gentleman. An ordinary optic nerve is about the thickness of a thread but his is like a cord. He must be a remarkable man in some walk of life. Who is he? It is certainly required great bodily vigor and physical capacity to sustain such fatigue as Edison has all his life imposed upon himself to the extent on one occasion of going five days without sleep. In a conversation during 1909 he remarked as though it were nothing out of the way that up to seven years previously his average of daily working hours was nineteen and one half but that sense then he figured it at eighteen. He said he stood it easily because he was interested in everything and was reading and studying all the time. For instance he had gone to bed the night before exactly at twelve and had arisen at four thirty a.m. to read some New York law reports. It was suggested that the secret of it might be that he did not live in the past but was always looking forward to a greater future to which he replied yes that's it I don't live with the past I am living for today and tomorrow. I am interested in every department of science arts and manufacture. I read all the time on astronomy chemistry biology physics music metaphysics mechanics and other branches political economy electricity and in fact all things that are making for progress in the world. I get all the proceedings of the scientific societies the principal scientific and trade journals and read them. I also read the clipper the police cassette the billboard the dramatic mirror and a lot of similar publications were like to know what is going on. In this way I keep up to date and live in a great moving world of my own and what's more I enjoy every minute of it. Referring to some event of the past he said spilt milk doesn't interest me I have spilt lots of it and while I have always felt it for a few days it is quickly forgotten and I turn again to the future. During another talk on Kindred affairs it was suggested to Edison that as he had worked so hard all his life it was about time for him to think somewhat of the pleasures of travel and the social side of life to which he replied laughingly I already have a schedule worked out from now until I am 75 years of age I expect to keep more or less busy with my regular work not however working as many hours or as hard as I have in the past. At 75 I expect to wear loud waistcoats with fancy buttons also gator tops. At 80 I expect to learn how to play bridge with and talk foolishly to the ladies. At 85 I expect to wear a full dress suit every evening at dinner and at 90 well I never play more than 30 years ahead. The reference to clothes is interesting as it is one of the few subjects in which Edison has no interest it rather bores him. His dress is always of the plainest in fact so plain that at the Bergman shops in New York the children attending a parochial Catholic school were want to salute him with the finger to the head every time he went by. Upon inquiring he found that they took him for a priest with his dark garb smooth-shaven face and serious expression. Edison says I get a suit that fits me then I compel the tailors to use that as a jig or pattern or blueprint to make others by. For many years a suit was used as a measurement once or twice they took fresh measurements but these didn't fit and they had to go back. I eat to keep my weight constant hence I never need change measurements. In regard to this Mr. Mallory furnishes a bit of chattis follows and a lawsuit in which I was a witness I went out to lunch with the lawyers on both sides and the lawyer who had been cross examining me stated that he had for a client a Fifth Avenue tailor who had told him that he had made all of Mr. Edison's clothes for the last 20 years and that he had never seen him. He said that some 20 years ago a suit was sent to him from orange and measurements were made from it and that every suit since had been made from these measurements. I may add from my own personal observation that in Mr. Edison's clothes there is no evidence but that every new suit that he has worn in that time looks as if it had been specially measured for it which shows how very little he has changed physically in the last 20 years. Edison has never had any taste for amusements although he will indulge in the game of parcheese and has a billiard table table in his house. The coming of the automobile was a great boon to him because it gave him a form of outdoor sport in which he could indulge in the spirit of observation without the guilty feeling that he was wasting valuable time. In his automobile he has made long tours and with his family has particularly indulged his taste for botany. That he has had the usual experience in running machines will be evidenced by the following little story from Mr. Mallory. About three years ago I had a motor car of a make of which Mr. Edison had already two cars and when the car was received I made inquiry as to whether any repair parts were carried by any of the various garages in eastern Pennsylvania near our cement works. I learned that this particular car was the only one in eastern. Knowing that Mr. Edison had had an experience lasting two or three years with this particular make of car I determined to ask him for information relative to repair parts so the next time I was at the laboratory I told him I was able to get any repair parts in eastern and that I wish to order some of the most necessary so that in case of breakdowns I would not be compelled to lose the use of the car for several days until the parts came from the automobile factory. I asked his advice as to what I should order to which he replied I don't think it will be necessary to order an extra top. Since that episode which will probably be appreciated by most automobilists Edison has taken up the electric automobile and is now using it as well as developing it. One of the cars equipped with his battery is the Bailey and Mr. B tells the following story in regard to it. One day Colonel Bailey of Amesbury, Massachusetts was visiting the automobile show in New York came out to the laboratory to see Mr. Edison as the latter had expressed his desire to talk with him on his next visit to the metropolis. When he arrived at the laboratory Mr. Edison who had been up all night experimenting was asleep on the cot in the library. As a rule we never awake Mr. Edison from sleep but as he wanted to see Colonel Bailey who had to go I felt that an exception should be made so I went and tapped him on the shoulder. He awoke at once smiling jumped up was instantly himself as usual and advanced and greeted the visitor. His very first question was well Colonel how did you come out on that experiment referring to some suggestions he had made at their last meeting a year before. For a minute Colonel Bailey did not recall what was referred to but a few words from Mr. Edison brought it back to his remembrance and he reported that the results have justified Mr. Edison's expectations. It might be expected that Edison would have extreme and even radical ideas on the subject of education and he has as well as a perfect readiness to express them because he considers that time is wasted on things that are not essential. What we need he has said are men capable of doing work. I wouldn't give a penny for the ordinary college graduate except those from the Institutes of Technology. Those coming up from the ranks are a darn sight better than the others. They aren't filled up with Latin philosophy and the rest of that nanny stuff. A further remark of his is what the country needs now is the practical skilled engineer who is capable of doing everything in three or four centuries when the country is settled and commercialism is diminished there will be time for the literary men. At present we want engineers industrial men, good business light managers and railroad men. It is hardly to be marveled at that such views should elicit warm protest summed up in the comment Mr. Edison and many like him see in reverse the course of human progress. Invention does not smooth the way for the practical men and make them possible. There is always too much danger of neglecting thoughts for things, ideas for machinery. No theory of education that aggravates this danger is consistent with national well-being. Edison is slow to discuss the great mysteries of life but is a reverential attitude of mind and ever tolerant of others beliefs. He is not a religious man in the sense of turning to forms and creeds but as might be expected is inclined as an inventor and creator to argue from the basis of design and then to infer a designer. After years of watching the processes of nature he says I can no more doubt the existence of an intelligence that is running things than I do of the existence of myself. Take for example the substance water that forms the crystals known as ice. Now there are hundreds of combinations that form crystals and every one of them save ice sinks in water. Ice I say doesn't and it is rather lucky for us mortals for if it had done so we would all be dead. Why? Simply because if ice sank to the bottoms of rivers, lakes, and oceans as fast as it froze those places would be frozen up and there would be no water left. There is only one example out of thousands that to me prove beyond possibility of a doubt that some vast intelligence is governing this and other planets. A few words as to the domestic and personal side of Edison's life to which many an incidental references have already been made in these pages. He was married in 1873 to Miss Mary Stillwell who died in 1884 leaving three children, Thomas Alva, William Leslie, and Marion Estelle. Mr. Edison was married again in 1886 to Miss Mina Miller daughter of Mr. Lewis Miller a distinguished pioneer inventor and manufacturer in the field of agricultural machinery and equally entitled to fame as the father of the Chautauqua idea and the founder with Bishop Vincent of the original Chautauqua which now has so many replicas all over the country and which started in motion one of the great modern educational and moral forces in America. By this marriage there are three children Charles, Madeleine, and Theodore. For over a score of years dating from his marriage to Miss Miller Edison's happy and perfect domestic life has been spent at Glenmont, a beautiful property acquired at that time in Llewellyn Park on the higher slopes of Orange Mountain, New Jersey with an easy walking distance of the laboratory at the foot of the hill in West Orange. As noted already the latter part of each winter is spent at Fort Myers, Florida where Edison has on the banks of the Callahoochee River a plantation home that is in many ways a miniature copy of the home and laboratory up north. Glenmont is a rather elaborate and florid building in Queen Anne English style of brick stone and wooden beams showing on the exterior with an abundance of gables and balconies. It is set in an environment of woods and sweeps of lawn flanked by unusually large conservatories and always brightened summer and glowing flowerbeds. It would be difficult to imagine Edison in a stiffly formal house and this big cozy three-story rambling mansion has an easy freedom about it without and within quite in keeping with the genius of the inventor but revealing at every turn traces of feminine taste and culture. The ground floor consisting chiefly of broad drawing rooms parlors and dining hall is chiefly noteworthy for the den or lounging room at the end of the main axis where the family and friends are likely to be found in the evening hours unless the party has withdrawn for more intimate social intercourse to the interesting and fascinating private library on the floor above. The lounging room on the ground floor is more or less of an Edison Museum for it is littered with souvenirs from great people and with mementos of travel all related to some event or episode. A large cabinet contains awards decorations and metals presented to Edison accumulating in the course of a long career some of which may be seen in the illustration opposite. Nearby may be noticed the bronze replica of the Edison gold metal which was founded in the American Institute of Electrical Engineers the first award of which was made to Elohu Thompson during the present year 1910. There are statues of serpentine marble, gifts of the late Tsar of Russia whose admiration is also represented by a gorgeous enlaid and enameled cigar case. There are typical bronze vases from the Society of Engineers of Japan and a striking death set of writing apparatus from Krupp all the pieces being made out of tiny but massive guns and shells of Krupp's deal. In addition to such bric-a-brac and bill-a-bots of all kinds are many pictures and photographs including the original sketches of the reception given to Edison in 1889 by the Paris Figaro and a letter from Madame Carnot placing the presidential opera box at the disposal of Mr. and Mrs. Edison. One of the most conspicuous features of the room is a phonograph equipment on which the latest and best productions by the greatest singers and musicians can always be heard but which Edison himself is everlastingly experimenting with under the uncurable delusion that this domestic retreat is but an extension of his laboratory. The big library, Simi Boudoir upstairs, is also very expressive of the home life of Edison but again typical of his nature and disposition for it is difficult to overlay his many technical books and scientific periodicals with a sufficiently thick crust of popular magazines or current literature to prevent their outcropping into evidence. In like manner the chat and conversation here, however lightly it may begin, turns invariably to large questions and deep problems, especially in the fields of discovery and invention and Edison in an easy chair will sit through the long evenings till one or two in the morning pulling meditatively at his eyebrows quoting something he has just read pertinent to the discussion, hearing and telling news stories with gusto offering all kinds of ingenious suggestions and without fail getting hold of pads and sheets of paper on which to make illustrative sketches. He is wonderfully handy with the pencil and will sometimes amuse himself while chatting with making all kinds of fancy bits of penmanship, twisting his signature into circles and squares but always writing straight lines so straight they could not be ruled to truer. Many a night it is a question of getting Edison to bed for he would much rather probe a problem than eat or sleep but at whatever hour the visitor retries or gets up he is sure to find the master of the house on hand serene and reposeful and just as brisket dawn is when he allowed the conversation to break up at midnight. The ordinary routine of daily family life is of course often interrupted by receptions and parties, visits to the billiard room, the entertainment of visitors, departure to and return from college at vacation periods of the young people and matters relating to the many social and philanthropic causes in which Mrs. Edison is actively interested but as a matter of fact Edison's round of toil and relaxation is singularly uniform and free from agitation and that is the way he would rather have it. Edison at sixty-three has a fine physique and being free from serious ailments of any kind should carry on the traditions of his long-lived ancestors as to a vigorous old age.  He stands five feet nine and one-half inches high, weighs one hundred and seventy-five pounds and has not varied as to weight in quarter of a century although as a young man he was slimmed to gauntness. His very epistemious, hardly ever touching alcohol carrying little from meat but fond of fruit and never averse to a strong cup of coffee or a good cigar. He takes extremely little exercise although his good color and quickness of step would suggest to those who do not know better that he is in the best of training and one who lives in the open air. His simplicity as to clothes has already been described. One would be startled to see him with a bright tie, a loud checked suit or a fancy waist coat and yet there is a curious sense of the steadiestness about the plain things he delights in. Perhaps he is not wholly responsible personally for his state of affairs. In conversation Edison is direct, courteous, ready to discuss a topic with anybody worth talking to and in spite of his sword deafness an excellent listener. No one ever goes away from Edison in doubt as to what he thinks or means but he is ever shy and diffident to a degree if the talk turns on himself rather than on his work. If the authors were asked after having written the foregoing pages to explain here the reason for Edison's success based upon their observations so far made they would first answer that he combines with a vigorous and normal physical structure a mind capable of clear and logical thinking and an imagination of unusual activity but this would by no means offer a complete explanation. There are many men of equal bodily and mental vigor who have not achieved a tithe of this accomplishment. What other factors are there to be taken into consideration to explain this phenomenon? First a stolid almost flimatic nervous system which takes absolutely no notice of NUE a system like that of a Chinese ivory carver who works day after day and month after month on a piece of material no larger than your hand. No better illustration of this characteristic can be found than in the development of the nickel pocket for the storage battery an element the size of a short lead pencil on which upper to five years are spent in experiments costing over a million dollars day after day always apparently with the same tubes but with small variations carefully tabulated in the notebooks to an ordinary person the mere sight of such a tube would have been as distasteful certainly after a week or so as a smell of a quail to a man striving to eat one every day for a month near the end of his gastronomic ordeal but to Edison these small perforated steel tubes held out as much of a fascination at the end of five years as when the search was first begun and every morning found him eager to begin the investigation in NUE as if the battery was an absolutely novel problem to which his thoughts had just been directed. Another and second characteristic of Edison's personality contributing so strongly to his achievements is an intense not to say courageous optimism in which no thought of failure can enter an optimism born of self-confidence and becoming after 40 or 50 years of experience more and more a sense of certainty in the accomplishments of success. In the overcoming of difficulties he has the same intellectual pleasure as a chess master when confronted with a problem requiring all the efforts of his skill and experience to solve to advance along smooth and pleasant paths to encounter no obstacles to wrestle with no difficulties and hardships such as absolutely no fascination to him. He meets obstruction with the keen delight of a strong man battling with the waves and opposing them in sheer enjoyment and the greater and more apparently overwhelming forces that may tend to sweep him back the more vigorous his own efforts to forge through them. At the conclusion of the or milling experiments when practically his entire fortune was sunk in an enterprise that had to be considered an impossibility when at the age of 50 he looked back upon five or six years of intense activity expended apparently for naught when everything seemed most black and the financial clouds were quickly gathering on the horizon, not the slightest idea of repining entered his mind. The main experiment had succeeded. He had accomplished what he sought for. Nature at another point had outstripped him yet he had broadened his own sum of knowledge to a prodigious extent. It was only during the past summer, 1910, that one of the writers spent a Sunday with him riding over the beautiful New Jersey roads in an automobile. Edison and the highest spirits and pointing out with the keenest enjoyment the many beautiful views of valley and wood. The wanderings led to the old or milling plant at Edison, now practically a mass of deserted buildings all going to decay. It was a depressing site marking such titanic but futile struggles with nature. To Edison, however, no trace of sentiment or regret occurred and the whole ruins were apparently as matter of concern as if he were viewing the remains of Pompeii. Sitting on the porch of the White House where he lived during that period in the light of the setting sun, his fine face and repose, he looked as placently over the scene as a happy farmer over a field of ripening corn. All that he said was, I never felt better in my life than during the five years I worked here. Hard work, nothing to divert my thought, clean air and simple food made my life very pleasant. We learned a great deal. It will be of benefit to someone, sometime. Similarly, in connection with the storage battery, after having experimented continuously for three years, it was found to fall below his expectations and its manufacture had to be stopped. Hundreds of thousands of dollars had been spent on the experiments and largely without Edison's consent, the battery had been very generally exploited in the press. To stop meant not only to pocket a great loss already incurred, facing a dark and uncertain future, but to most men animated by ordinary human feelings and meant more than anything else, an injury to personal pride. Pride? That had nothing to do with really serious practical problem, and the writers can testify that at the moment when his decision was reached, work stopped and the long vista ahead was peered into. Edison was as little concerned as if he had concluded that after all, perhaps peach pie might be better for a present diet than apple pie. He has often said that time meant very little to him, that he had but a small realization of its passage, and that ten or twenty years were as nothing when considering the development of a vital invention. These references to personal pride recall another characteristic of Edison wherein he differs from most men. There are many individuals who derive an intense and not improper pleasure and regalia of military garments with plenty of gold braid and brass buttons and thus a raid and appearing before their friends and neighbors. Putting at the head of the procession the man who makes his appeal to public attention solely because of the brilliancy of his plumage, and passing down the ranks to the multitudes having a gradually decreasing sense of vanity in their personal accomplishment, Edison would be placed at the very end. Reference herein has been made to the fact that one of the two great English universities wished to confer a degree upon him, but that he was unable to leave his work for the brief time necessary to accept the honor. At that occasion it was pointed out to him that he should make every possible sacrifice to go, that the compliment was great, and that but few Americans had been so recognized. It was hopeless and appeal based on sentiment. Before him was something real, work to be accomplished, a problem to be solved. Beyond was a prize as intangible as the button of the Legion of Honor which he concealed from his friends that they might not feel he was showing off. The fact is that Edison cares little for the approval of the world, that he cares everything for the approval of himself. Difficult as it may be, perhaps impossible to trace its origin, Edison possesses what he would probably call a well-developed case of New England conscience for whose approval he is incessantly occupied. These then may be taken as the characteristics of Edison that have enabled him to accomplish more than most men. A strong body, a clear and active mind, a developed imagination, a capacity of great mental and physical concentration, an ironclad nervous system that knows no ennui, intense optimism and courageous self-confidence. Anyone having these capacities developed to the same extent with the same opportunities for use would probably accomplish as much. And yet there is a peculiarity about him so far that is known has never been referred to before in print. He seems to be conscientiously afraid of appearing indolent, and in consequence subjects himself regularly to unnecessary hardship. Working all night is seldom necessary until two or three o'clock in the morning, yet even now he persists in such tests to pen his strength. Recently one of the writers had occasion to present to him a long typewritten document of upward of thirty pages for his approval. It was taken home to Glenmont. Edison had a few minor corrections to make, probably not more than a dozen all told. They could have been embodied by inter-alineations and marginal notes in the ordinary way and certainly would not have required more than ten or fifteen minutes of his time. Yet what did he do? He copied out painstakingly the entire paper in long hand, embodying corrections as he went along and presented the result of his work the following morning. At the very least such a task must have occupied several hours. How can such a trait and scores of similar experiences could be given be explained except by the fact that evidently he felt the need of special schooling and industry that under no circumstances must he allow a thought of indolence to enter his mind? Undoubtedly in the days to come Edison will not only be recognized as an intellectual prodigy, but as a prodigy of industry, of hard work. In his field as inventor and man of science he stands as clear-cut and secure as the lighthouse on a rock and is indifferent to the tumult around. But as the old man, and before he was thirty years old he was affectionately so called by his laboratory associates, he is a normal, fun-loving typical American. His sense of humor is intense, but not of the hot house over developed variety. One of his favorite jokes is to enter the legal department with an air of great humility and apply for a job as an inventor. Never is he so preoccupied or fretted with cares as not to drop all thought of his work for a few moments to listen to a new story with a ready smile all the while and a hearty, boyish laugh at the end. His laugh, in fact, is sometimes almost aboriginal, slapping his hands delightedly on his knees, he rocks back and forth and fairly shouts his pleasure. Recently a daily report of one of these companies that had been just started contained a large order amounting to several thousand dollars and was returned by him with a miniature sketch of a small individual viewing that particular item through a telescope. His facility in making hasty but intensely graphic sketches is proverbial. He takes great delight in imitating the lingo of the New York street gaymen. A dignified person named James may be greeted with, hello, gee. Jimmy, when did Jews blow in? He likes to mimic and imitate types, generally, that are distasteful to him. The sanctimonious hypocrite, the sleek speculator and others whom he has probably encountered in life are done to the Queen's taste. One very cold winter's day he entered the laboratory library in fine spirits doing the decay dandy with imaginary cane under his arm, struggling to put on a pair of tattered imaginary gloves with a self satisfied smirk and leer that would have done credit to a real comedian. This particular bit of acting was heightened by the fact that even in the coldest weather he wears thin summer clothes, generally acid worn and more or less disreputable. For protection he varies the number of his suits of underclothing, sometimes wearing three or four sets, according to the thermometer. If one could divorce Edison from the idea of work and could regard him separate and apart from his embodiment as an inventor and man of science, it might truly be asserted that his temperament is essentially mercurial.  Anger with him, however, is a good deal like the story attributed to Napoleon. Sire, how is it that your judgment is not affected by your great rage? asked one of his courteous. Because, said the emperor, I never allow it to rise above this line, drawing his hand across his throat.  His voice raised to a high pitch, sneeringly expressing his feelings of contempt for the offender. And yet, when the culprit, like a bad schoolboy, has left the room, Edison has immediately returned to his normal poise and the incident is a thing of the past. At other times, the unsettled condition persists and his spleen is vented not only on the original instigator, but upon others who may have occasion to see him, sometimes hours afterward. When such a fit is on him, the word is quickly passed around, and but few of his associates find it necessary to consult with him at the time. The genuine anger can generally be distinguished from the imitation article by those who know him intimately by the fact that when really enraged, his forehead between the eyes partakes of a curious rotary movement that cannot be adequately described in words. It is as if the storm clouds within are moving like a whirling cyclone. As a general rule, Edison does not get genuinely angry at mistakes and other human weaknesses of his subordinates. At best, he merely simulates anger. But woe be tied the one who has committed an act of bad faith, treachery, dishonesty, or ingratitude, then Edison can show what it is for a strong man to get downright mad. But in this respect, he is singularly free, and his spells of anger are really few. In fact, those who know him best are continually surprised at his moderation and patience, often where there has been great provocation. People who come in contact with him and who may have occasion to oppose his views may leave with the impression that he is hot-tempered. Nothing could be further from the truth. He argues his point with great vehemence, pounds on the table to emphasize his views, and illustrates his theme with a wealth of semiles. But on account of his deafness, it is difficult to make the argument really two-sided. Before the visitor can fully explain his side of the matter, some point is brought up that starts Edison off again, and new arguments from his viewpoint are poured forth. This constant interruption is taken by many to mean that Edison has a small opinion of any arguments that oppose him. But he is only intensely in earnest in presenting his own side. If the visitor persists until Edison has seen both sides of the controversy, he is always willing to frankly admit that his own views may be unsound and that his opponent is right. In fact, after such a controversy, both parties going after each other hammering tongs, the arguments to him being carried on at the very top of one's voice to enable him to hear, and from him being equally loud in the excitement of the discussion, he has often said, I see now that my position was absolutely rotten. Obviously, however, all of these personal characteristics have nothing to do with Edison's position in the world of affairs. They show him to be a plain, easygoing, placid American with no sense of self-importance and ready at all times to have his mind turned into a lighter channel. In private life, they show him to be a good citizen, a good family man, absolutely moral, temperate in all things, and of great charitableness to all mankind. But what of his position in the age in which he lives? Where does he rank in the mountain range of great Americans? Is it believed that from the other chapters of this book, the reader can formulate his own answer to the question? End of chapter 29. Introduction to the appendix 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 Melissa. Edison, His Life and Inventions by Frank Louis Dyer and Thomas Cumberford Martin. Introduction to the appendix. The reader who has followed the foregoing narrative may feel that in as much as it is intended to be a historical document, an appropriate addendum there too would be a digest of all the inventions of Edison. The desirability of such a digest is not to be denied. But as there are some 2,500 or more inventions to be considered, including those covered by caveats, the task of its preparation would be stupendous. Besides, the resultant data would extend this book into several additional volumes. Thereby rendering it of value chiefly to the technical student, but taking it beyond the bounds of biography. We should, however, deem our presentation of Mr. Edison's work to be imperfectly executed if we neglected to include an intelligible exposition of the broader theoretical principles of his more important inventions. In the following appendix we have therefore endeavored to present a few brief statements regarding Mr. Edison's principle inventions, classified as to subject matter, and explained in languages free from technicalities as is possible. No attempt has been made to conform with strictly scientific terminology, but, for the benefit of the general reader, well understood conventional expressions, such as flow of current, etc., have been employed. It should be borne in mind that each of the following items has been treated as a whole or class, generally speaking, and not as a digest of all the individual patents relating to it. Anyone who is sufficiently interested can obtain copies of any of the patents referred to for five cents each by addressing the commission of patents, Washington, DC. End of introduction to the appendix. Appendix 1 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 Melissa. Edison, His Life and Inventions, by Frank Louis Dyer and Thomas Comerford Martin. Appendix 1, The Stock Printer. In these modern days, when the stock ticker is in universal use, one seldom, if ever, hears the name of Edison, coupled with a little instrument whose chatterings have such tremendous import to the whole world. It is of much interest, however, to remember the fact that it was by reason of his notable work in connection with this device that he first became known as an inventor. Indeed, it was through the intrinsic merits of his improvements in stock tickers that he made his real entree into commercial life. The idea of the ticker did not originate with Edison, as we have already seen in Chapter 7 of the preceding narrative. But at the time of his employment with the Western Union in Boston in 1868, the crudities of the early forms made an impression on his practical mind, and he got out an improved instrument of his own, which he introduced in Boston through the aid of a professional promoter. Edison, then only 21, had less business experience than the promoter. Through his manipulation, he soon lost his financial interest in this early ticker enterprise. The narrative tells of his coming to New York in 1869 and immediately plunging into the business of gold in stock reporting. It was at this period that his real work on stock printers commenced, first individually and later as a co-worker with FL Pope. This inventive period extended over a number of years, during which time he took out 46 patents on stock printing instruments and devices, two of such patents being issued to Edison and Pope as joint inventors. These various inventions were mostly in the line of development of the art as it progressed during these early years. But out of it all came the Edison Universal Printer, which entered into very extensive use and which is still used throughout the United States and in some foreign countries to a considerable extent at this very day. Edison's inventive work on stock printers has left its mark upon the art as it exists at the present time. In his earlier work, he directed his attention to the employment of a single circuit system in which only one wire was required. The two operations of setting the type wheels and of printing being controlled by separate electromagnets, which were actuated through polarized relays, as occasion required, one polarity energizing the electromagnet controlling the type wheels and the opposite polarity energizing the electromagnet controlling the printing. Later on, however, he changed over to a two-wire circuit, such as shown in Figure 2 of this article in connection with the Universal Stock Printer. In the earliest days of the stock printer, Edison realized the vital commercial importance of having all instruments recording precisely alike at the same moment. And it was he who first devised, in 1969, the unison stop, by means of which all connected instruments could at any moment be brought to zero from the central transmitting station and thus be made to work in correspondence with the central instrument and with one another. He also originated the idea of using only one inking pad and shifting it from side to side to ink the type wheels. It was also an Edison stock printer that the principle of shifting type wheels was first employed. Hence, it will be seen that, as in many other arts, he made a lasting impression in this one by the intrinsic merits of the improvements resulting from his work therein. We shall not attempt to digest the 46 patents above named, nor to follow Edison through the progressive steps which led to the completion of his universal printer, but shall simply present a sketch of the instrument itself and followed with a very brief and general explanation of its theory. The Edison universal printer, as it virtually appears in practice, is illustrated in figure one below, from which it will be seen that the most prominent parts are the two type wheels, the inking pad, and the paper tape feeding from the reel, all appropriately placed in a substantial framework. The electromagnets and other actuating mechanism cannot be seen plainly in this figure, but are produced diagrammatically in figure two and somewhat enlarged for convenience of explanation. It will be seen that there are two electromagnets, one of which, T.M., is known as the type magnet, and the other, P.M., as the press magnet, the former having to do with the operation of the type wheels and the latter with the pressing of the paper tape against them. As will be seen from the diagram, the armature A of the type magnet has an extension arm on the end of which is an escarpment engaging with the toothed wheel placed at the extremity of the shaft carrying the type wheels. This extension arm is pivoted at B. Hence, as the armature is alternately attracted when current passes around its electromagnet and drawn up by the spring on cessation of current, it moves up and down, thus actuating the escarpment and causing a rotation of the toothed wheel in the direction of the arrow. This, in turn, brings any desired letters or figures on the type wheels to a central point where they may be impressed upon the paper tape. One type wheel carries letters and the other one figures. These two wheels are mounted rigidly on a sleeve carried by the wheel shaft. As it is desired to print from only one type wheel at a time, it becomes necessary to shift them back and forth from time to time in order to bring the desired characters in line with the paper tape. This is accomplished through the movements of a three-arm rocking lever attached to the wheel sleeve at the end of the shaft. This lever is actuated through the agency of two small pins carried by an arm projecting from the press lever, P.L. As the ladder moves up and down, the pins play upon the underside of the lower arm of the rocking lever, thus canting it and pushing the type wheels to the right or left as the case may be. The operation of shifting the type wheels will be given further on. The press lever is actuated by the press magnet. From the diagram, it will be seen that the armature of the ladder has a long pivoted extension arm, or platen, trough-like in shape in which the paper tape runs. It has already been noted that the object of the press lever is to press this tape against that character of the type wheel centrally located above it at the moment. It will at once be perceived that this action takes place when current flows through the electromagnet and its armature is attracted downward, the platen again dropping away from the type wheel as the armature is released upon cessation of current. The paper feed is shown at the end of the press lever and consists of a push dog, or pawl, which operates to urge the paper forward as the press lever descends. The worm gear, which appears in the diagram on the shaft near the toothed wheel, forms part of the unison stop above referred to. But this device is not shown in full in order to avoid unnecessary complications of the drawing. At the right-hand side of the diagram, figure two, is shown a portion of the transmitting apparatus at a central office. Generally speaking, this consists of a motor-driven cylinder having metallic pins placed at intervals and arranged spirally around its periphery. These pins correspond to the number to the characters on the type wheels. A keyboard, not shown, is arranged above the cylinder, having keys lettered and numbered corresponding to the letters and figures on the type wheels. Upon depressing any one of these keys, the motion of the cylinder is arrested when one of its pins is caught and held by the depressed key. When the key is released, the cylinder continues in motion. Hence, it is evident that the revolution of the cylinder may be interrupted as often as desired by manipulation of the various keys in transmitting the letters and figures which are to be recorded by the printing instrument. The method of transmission will presently appear. In the sketch, figure two, there will be seen mounted upon the cylinder shaft, two wheels made up of metallic segments insulated from each other, and upon the hubs of these wheels are two brushes, which connect with the main battery. Resting upon the periphery of these two segmental wheels, there are two brushes to which are connected the wires, which carry the battery current to the type magnet and press magnet, respectively, as the brushes make circuit by coming in contact with the metallic segments. It will be remembered that upon the cylinder, there are as many pins as there are characters on the type wheels of the ticker. And one of the segmental wheels, W, has a like number of metallic segments, while upon the other wheel, W prime, there are only one half that number. The wheel W controls the supply of current to the press magnet and the wheel W prime to the type magnet. The type magnet advances the letter and figure wheels one step when the magnet is energized and a succeeding step when the circuit is broken. Hence, the metallic contact surfaces on wheel prime are, as stated, only half as many as on the wheel W, which controls the press magnet. It should be borne in mind, however, that the contact surfaces and insulated surfaces on wheel W prime are together equal in number to the characters on the type wheels. But the retractile spring of TM does have the work of operating the escarpment. On the other hand, the wheel W has the full number of contact surfaces because it must provide for the operative closure of the press magnet circuit whether the brush B prime is an engagement with a metallic segment or an insulated segment of the wheel W prime. As the cylinder revolves, the wheels are carried around with its shaft and current impulses flow through the wires to the magnets as the brushes make contact with the metallic segments of these wheels. One example will be sufficient to convey to the reader an idea of the operation of the apparatus. Assuming, for instance, that it is desired to send out the letters AM to the printer, let us suppose that the pin corresponding to the letter A is at one end of the cylinder and near the upper part of its periphery and that the letter M is about the center of the cylinder and near the lower part of its periphery. The operator of the keyboard would depress the letter A, whereupon the cylinder would in its revolution bring the first named pin against the key. During the rotation of the cylinder, a current would pass through wheel W prime and actuate TM, drawing down the armature and operating the escarpment, which would bring the type wheel to a point where the letter A would be central as regards the paper tape. When the cylinder came to rest, current would flow through the brush of wheel W to PM and its armature would be attracted, causing the platen to be lifted and thus bringing the paper tape in contact with the type wheel and printing the letter A. The operator next sends the letter M by depressing the appropriate key. On account of the position of the corresponding pin, the cylinder would make nearly half a revolution before bringing the pin to the key. During this half revolution, the segmental wheels have also been turning and the brushes have transmitted a number of current impulses to TM, which have caused it to operate the escarpment a corresponding number of times, thus turning the type wheels around to the letter M. When the cylinder stops, current once more goes to the press magnet and the operation of lifting and printing is repeated. As a matter of fact, current flows over both circuits as the cylinder is rotated, but the press magnet is purposely made to be comparatively sluggish and the narrowness of the segments on wheel W tend to diminish the flow of current in the press circuit until the cylinder comes to rest when the current continuously flows over that circuit without interruption and fully energizes the press magnet. The shifting of the type wheels is brought about as follows. On the keyboard of the transmitter, there are two characters known as dots, namely the letter dot and the figure dot. If the operator presses one of these dot keys, it is engaged by an appropriate pin on the revolving cylinder. Meanwhile, the type wheels are rotating, carrying with them the rocking lever, and current is pulsating over both circuits. When the type wheels have arrived to the proper point, the rocking lever has been carried to a position where its lower arm is directly over one of the pins on the arm extending from the platen to the press lever. The cylinder stops and current operates the sluggish press magnet, causing its armature to be attracted, thus lifting the platen and its projecting arm. As the arm lifts upward, the pin moves along the underside of the lower arm of the rocking lever thus causing it to can't and shift the type wheels to the right or left as desired. The principles of operation of this apparatus have been confined to a very brief and general description, but it is believed to be sufficient for the scope of this article. Note, the illustrations in this article are reproduced from American Telegraphy and Encyclopedia of the Telegraph by William Maver Jr., by permission of Maver Publishing Company, New York. End of Appendix 1. The Quadraplex and Phonoplex Edison's work in stock printers and telegraphy had marked him as a rising man in the electrical art of the period, but his invention of quadraplex telegraphy in 1874 was what brought him very prominently before the notice of the public. Duplex telegraphy or the sending of two separate messages in opposite directions at the same time as the telegraph at the same time over one line was known and practiced previous to this time, but quadraplex telegraphy or the simultaneous sending of four separate messages two in each direction over a single line had not been successfully accomplished, although it had been the subject of many an inventor's dream and the object of anxious efforts for many long years. In the early part of 1873 and for some time afterward the system invented by Joseph Stearns was the duplex in practical use. In April of that year, however, Edison took up the study of the subject and filed two applications for patents. One of these applications embraced an invention by which two messages could be sent not only duplex or in opposite directions as above explained, but could also be sent duplex, that is to say in one direction simultaneously as separate and distinct messages over the one line. Thus there was introduced a new feature into the art of multiplex telegraphy for whereas duplexing accomplished by varying the strength of the current permitted messages to be sent simultaneously from opposite stations. Diplexing achieved by also varying the direction of the current permitted the simultaneous transmission of two messages from the same station and their separate reception at the distance station. The quadruplex was the tempting goal toward which Edison now constantly turned and after more than a year's strenuous work he filed a number of applications for patents in the late summer of 1874. Among them was one which issued some years afterward as patent number 480,567 covering his well known quadruplex. He had improved his own diplex combined it with one of the Stern's duplex and thereby produced a system by means of which four messages could be sent over a single line at the same time two in each direction. As the reader will probably be interested to learn something of the theoretical principles of this fascinating invention we shall endeavor to offer a brief and condensed explanation thereof with as little technicality as the subject will permit. This explanation will necessarily be of somewhat elementary character for the benefit of the lay reader whose indulgence is asked for an occasional reiteration introduced for the sake of clearness of comprehension. While the apparatus and the circuits are for the sake seemingly very intricate the principles are really quite simple and the difficulty of comprehension is more apparent than real if the underlying phenomena are studied attentively. At the root of all systems of telegraphy including multiplex systems there lies the single basic principle upon which their performance depends namely the obtaining of a slight mechanical movement at the more or less distant end of a telegraph line. This is accompanied through the utilization of the phenomena of electromagnetism. These phenomena are easy of comprehension and demonstration. If a rod of soft iron be wound around with a number of turns of insulated wire and a current of electricity be sent through the wire the rod will be instantly magnetized and will remain a magnet as long as the current flows. But when the current is cut off the magnetic effect instantly ceases. This device is known as an electromagnet and the charging and discharging of such a magnet may of course be repeated indefinitely. In as much a magnet that has the power of attracting to itself pieces of iron or steel the basic importance of an electromagnet in telegraphy will be at once apparent when we consider the sounder whose clicks are familiar to every ear. This instrument consists essentially of an electromagnet of horseshoe form with its two poles close together and with its armature a bar of iron maintained in close proximity to the poles but kept normally in a retracted position by a spring. When the distant operator presses down his key the circuit is closed and a current passes along the line and through the generally two coils of the electromagnet thus magnetizing the iron core. Its attractive power draws the armature toward the poles. When the operator releases the pressure on his key the circuit is broken current does not flow the magnetic effect ceases and the armature is drawn back by its spring. These movements give rise to the clicking sounds which represent the dots and dashes of the Morse or other alphabet as transmitted by the operator. Similar movements produced in like manner are availed of in another instrument known as the relay whose office is to act practically as an automatic transmitter key repeating the messages received in its coils and sending them on to the next section of the line equipped with its own battery or when the message is intended for its own station sending the message to an adjacent sounder included in a local battery circuit. With a simple circuit therefore between two stations and where an intermediate battery is not necessary a relay is not used. Passing on to the consideration of another phase of the phenomena of electromagnetism the reader's attention is called to figure one in which will be seen on the left a simple form of electromagnet consisting of a bar of soft iron wound around with insulated wire through which a current is flowing from a battery. The arrows indicate the direction of flow. All magnets have two poles, north and south. A permanent magnet made of steel which has distinguished from soft iron retains its magnetism for long periods is so called because it's permanently magnetized and its polarity remains fixed. In an electromagnet the magnetism exists only as long as the current is flowing through the wire and the polarity of the soft iron bar is determined by the direction of flow of current around it for the time being. If the direction is reversed the polarity will also be reversed. Assuming for instance the bar to be and on toward the observer that end will be a south pole if the current is flowing from left to right clockwise around the bar or a north pole if flowing in the other direction as illustrated at the right of the figure. It is immaterial which way wire is round around the bar the determining factor of polarity being the direction of the current. It will be clear therefore that if two equal currents be passed around a bar in opposite directions, figure three they will tend to produce exactly opposite polarities and thus neutralize each other. Hence the bar would remain non-magnetic. As the path to the quadruplex passes through the duplex let us consider the Stern's system after noting one other principle namely that if more than one path is presented in which an electric current may complete its circuit it divides in proportion to the resistance of each path. Hence if we connect one pole of a battery with the earth and from the other pole run to the earth two wires of equal resistance as illustrated in figure two equal currents will traverse the wires. The above principles were employed in the Stern's differential duplex system in the following manner. Referring to figure three suppose a wire A is led from a battery around a bar of soft iron from left to right and another wire of equal resistance an equal number of turns B around from right to left. The flow of current will cause two equal opposing actions to be set up in the bar. One will exactly offset the other and no magnetic effect will be produced. A relay thus wound is known as a differential relay more generally called a neutral relay. The non-technical reader may wonder what use can possibly be made of an apparently non-operative piece of apparatus. It must be borne in mind however in considering a duplex system that a differential relay is used at each end of the line and forms part of the circuit and that while each relay must be absolutely unresponsive to the signals sent out from its home office it must respond to signals transmitted by a distant office. Hence the next figure four with its accompanying explanation will probably make the matter clear. If another battery D be introduced at the distant end of the wire A the differential or neutral relay becomes actively operative as follows. Battery C supplies wires A and B with equal current but battery D doubles the strength of the current traversing wire A. This is sufficient to not only neutralize the magnetism which the current in wire B would tend to set up but also by reason of the excess of current in wire A to make the bar a magnet whose polarity would be determined by the direction of the flow of current around it. In the arrangement shown in figure four the batteries are so connected that current flow is in the same direction thus doubling the amount of current flowing through wire A. But suppose the batteries were so connected that the current from each set flowed in an opposite direction. The result would be that these currents would oppose and neutralize each other and therefore none would flow in wire A. In as much however as there is nothing to hinder current would flow from battery C through wire B and the bar would therefore be magnetized. Hence assuming that the relay is to be actuated from the distant end D it is in a sense immaterial whether the batteries connected with wire A assist or oppose each other as in either case the bar would be magnetized only through the operation of the distant key. A slight elaboration of figure four will further illustrate the principle of the differential duplex. In figure five are two stations A, the home end and B, the distant station to which a message is to be sent. The relay at each end has two coils one and two. Number one in each case being known as the main line coil and two as the artificial line coil. The latter in each case has in its circuit a resistance R to compensate for the resistance of the main line so that there shall be no inequalities in the circuits. The artificial line as well as that to which the two coils are joined are connected to earth. There is a battery C and a key K. When the key is depressed current flows through the relay coils at A but no magnetism is produced as they oppose each other. The current however flows out through the main line coil over the line and through the main line coil one at B completing its circuit to earth and magnetizing the bar of the relay thus causing its armature to be attracted. On releasing the key the circuit is broken and magnetism instantly ceases. It will be evident therefore that the operator at A may cause the relay at B to act without affecting its own relay. Similar effects would be produced from B to A if the battery and key were placed at the B end. If therefore like instruments are placed at each end of a line as in figure six we have a differential duplex arrangement by means of which two operators may actuate relays at the ends distant from them without causing the operation of the relays at their home ends. In practice this is done by means of a special instrument known as a continuity preserving transmitter or usually as a transmitter. This consists of an electromagnet T operated by a key K and separate battery. The armature lever L is long pivoted in the center and is bent over at the end. At a point little beyond its center is a small piece of insulating material to which is screwed a strip of spring metal S. Conveniently placed with reference to the end of the lever is a bent metallic piece P. Having contact screw in its upper horizontal arm and attached to the lower end of this bent piece is a post or standard to which the main battery is electrically connected. The relay coils are connected by wire to the spring piece S and the armature lever is connected to earth. If the key is depressed the armature is attracted and its bent end is moved upward depressing the spring which makes contact with the upper screw which places the battery to the line and simultaneously breaks the ground connection between the spring and the upturned end of the lever as shown on the left. When the key is released the battery is again connected to earth. The compensating resistances and condensers necessary for a duplex arrangement are shown in the diagram. In figure six one transmitter is shown as closed at A while the other one is open. From our previous illustrations and explanations it will be readily seen that the transmitter closed at station A current flows via post P through S and to both relay coils at A then over the main line to main line coil at B and down to earth through S and the armature lever with its grounded wire. The relay at A would be unresponsive but the core of the relay at B would be magnetized and its armature respond to signals from A. In like manner if the transmitter at B be closed current would flow through similar parts and thus cause the relay at A to respond. If both transmitters be closed simultaneously both batteries will be placed to the line which would practically result in doubling the current in each of the main line coils in consequence of which both relays are energized and their armatures attracted through the operation of the keys at the distant ends. Hence two messages can be sent in opposite directions over the same line simultaneously. The reader will undoubtedly see quite clearly from the above system which rests upon varying the strength of the current that the two messages could not be sent in the same direction over the one line at the same time. To accomplish this object Edison introduced another and distinct feature, namely the using of the same current but also varying its direction of flow. That is to say alternately reversing the polarity of the batteries as applied to the line and thus producing corresponding changes in the polarity of another specially constructed type of relay called a polarized relay. To afford the reader a clear conception of such a relay we would refer again to figure one and its explanation from which it appears that the polarity of a soft iron bar is determined not by the strength of the current flowing around it but by the direction thereof. With this idea clearly in mind the theory of the polarized relay generally called polar relay as presented in the diagram figure seven will be readily understood. As is a bar of soft iron bent as shown and wound around with insulated copper wire the ends of which are connected with a battery B thus forming an electromagnet. An essential part of this relay consists of a swinging permanent magnet C whose polarity remains fixed. That end between the terminals of the electromagnet being a north pole. In as much as unlike poles of magnets are attracted to each other and like poles repelled it follows that this north pole will be repelled by the north pole of the electromagnet but will swing over and be attracted by its south pole. If the direction of flow of current be reversed by reversing the battery the electromagnetic polarity also reverses and the end of the permanent magnet swings over to the other side. This is shown in the two figures of figure seven. This device being a relay its purpose is to repeat transmitted signals into a local circuit as before explained. For this purpose there are provided at D and E a contact and a backstop the former of which is opened and closed by the swinging permanent magnet thus opening and closing the local circuit. Manifestally there must be provided some convenient way for rapidly transposing the direction of the current flow if such a device as the polar relay is to be used for the reception of telegraph messages and this is accomplished by means of an instrument called a pole changer which consists essentially of a movable contact piece connected permanently to the earth or grounded and arranged to connect one or the other pole of a battery to the line and simultaneously ground the other pole. This action of the pole changer is affected by movements of the armature of an electromagnet through the manipulation of an ordinary telegraph key by an operator at the home station as in the operation of the transmitter above referred to. By a combination of the neutral relay and the polar relay two operators by manipulating two telegraph keys in the ordinary way can simultaneously send two messages over one line in the same direction with the same current one operator varying its strength and the other operator varying its polarity or direction of flow. This principle was covered by Edison's patent number 162,633 and was known as the diplex system. Although in the patent referred to Edison showed and claimed the adaptation of the principle to duplex telegraphy. Indeed, as a matter of fact it was found that by winding the polar relay differently and arranging the circuits and collateral appliances appropriately the polar duplex system was more highly efficient than the neutral system and it is extensively used to the present day. Thus far we have referred to two systems one the neutral or differential duplex and the other the combination of the neutral and polar relays making a diplex system. By one of these two systems a single wire could be used for sending two messages in opposite directions and by the other in the same direction or in opposite directions. Edison followed up his work on the diplex and combined the two systems into a quadriplex by means of which four messages could be sent and received simultaneously over the one wire two in each direction thus employing eight operators four at each end two sending and two receiving. The general principles of quadriplex telegraphy are based upon the phenomena which we have briefly outlined in connection with the neutral relay and the polar relay. The equipment of such a system at each end of the line consists of these two instruments together with the special form of transmitter and the pole changer and their keys for actuating the neutral and polar relays at the other or distant end. Besides these there are the compensating resistances and condensers. All of these will be seen in the diagram figure eight. It will be understood of course that the polar relay as used in the quadriplex system is wound differently and therefore its operation is somewhat similar in principle to that of the differentially wound neutral relay in that it does not respond to the operation of the key at the home office but only operates in response to the movements of the distant key. Our explanation has merely aimed to show the underlying phenomena and principles in broad outline without entering into more detail than was deemed absolutely necessary. It should be stated however that between the outline and the filling in of the details there was an enormous amount of hard work, study, patient plotting and endless experiments before Edison finally perfected his quadriplex system in the year 1874. If it were attempted to offer here a detailed explanation of the varied and numerous operations of the quadriplex this article would assume the proportions of a treatise. An idea of their complexity may be gathered from the following which is quoted from American Telegraphy and Encyclopedia of the Telegraph by William Maver Jr. It may well be doubted whether in the whole range of applied electricity there occurs such beautiful combinations so quickly made, broken up and others reformed as in the operation of the Edison quadriplex. For example it is quite demonstrable that during the making of a simple dash of the more self-abept by the neutral relay at the home station the distant pole changer may reverse its battery several times. The home pole changer may do likewise and the home transmitter may increase and decrease the electromotive force of the home battery repeatedly. Simultaneously and of course as a consequence of the foregoing actions the home neutral relay itself may have had its magnetism reversed several times and the signal that is the dash will have been made partly by the home battery, partly by the distant and home batteries combined, partly by current on the mainline and partly by current on the artificial line, partly by the mainline static current, partly by the condenser static current and yet on a well-adjusted circuit the dash will have been produced on the quadriplex sounder as clearly as any dash on an ordinary single wire sounder. We present a diagrammatic illustration of the Edison quadriplex battery key system in figure eight and refer the reader to the above or other textbooks if he desires to make a close study of its intricate operations. Before finally dismissing the quadriplex and for the benefit of the inquiring reader who may vainly puzzle over the intricacies of the circuits shown in figure eight a hint as to an essential difference between the neutral relay as used in the duplex and as used in the quadriplex may be given. With the duplex as we have seen the current on the mainline is changed in strength only when both keys at opposite stations are closed together so that a current due to both batteries flows over the mainline. When a single message is sent from one station to the other or when both stations are sending messages that do not conflict only one battery or the other is connected to the mainline but with the quadriplex suppose one of the operators in New York for instance is sending reversals of current to Chicago. We can readily see how these changes in polarity will operate the polar relay at the distant station but why will they not also operate the neutral relay at the distant station as well. This difficulty was solved by dividing the battery at each station into two unequal parts. The smaller battery being always in circuit with the pole changer ready to have its polarity reversed on the mainline to operate the distant polar relay but the spring retracting the armature of the neutral relay is made so stiff as to resist these weak currents. If however the transmitter is operated at the same end the entire battery is connected to the mainline and the strength of this current is sufficient to operate the neutral relay. Whether the part or all of the battery is alternately connected or disconnected from the mainline by the transmitter the current so varied in strength is subject to reversal of polarity by the pole changer but the variations in strength have no effect upon the distant polar relay because that relay being responsive to changes in polarity of a weak current is obviously responsive to corresponding changes in polarity of a powerful current. With this distinction before him the reader will have no difficulty in following the circuits of figure eight bearing always in mind that by reason of the differential winding of the polar and neutral relays neither of the relays at one station will respond to the home battery and can only respond to the distant battery. The polar relay responding when the polarity of the current is reversed whether the current be strong or weak and the neutral relay responding when the line current is increased regardless of its polarity. It should be added that besides the system illustrated in figure eight which is known as the differential principle the quadruplex was also arranged to operate on the Wheatstone bridge principle but it is not deemed necessary to enter into its details. The underlying phenomena were similar the difference consisting largely in the arrangement of the circuits and apparatus. Edison made another notable contribution to multiplex telegraphy some years later in the phonoplex. The name suggests the use of the telephone and such indeed is the case. The necessity for this invention arose out of the problem of increasing the capacity of telegraph lines employed in through and way service such as upon railroads. In a railroad system there are usually two terminal stations and a number of way stations. There is naturally much intercommunication which would be greatly curtailed by a system having the capacity of only a single message at a time. The duplexes above described could not be used on a railroad telegraph system because of the necessity of electrically balancing the line which while entirely feasible on a through line would not be practicable between a number of intercommunicating points. Edison's phonoplex normally doubled the capacity of telegraph lines whether employed on way business or through traffic but in actual practice made it possible to obtain more than double service. It has been in practical use for many years on some of the leading railroads of the United States. The system is a combination of telegraphic apparatus and telephone receiver although in this case the latter instrument is not used in the generally understood manner. It is well known that the diaphragm of a telephone vibrates with the fluctuations of the current energizing the magnet beneath it. If the make and break of the magnetizing current be rapid the vibrations being within the limits of the human ear the diaphragm will produce an audible sound but if the make and break be as slow as with the ordinary Morse transmission the diaphragm will be merely flexed and return to its original form without producing a sound. If therefore there be placed in the same circuit a regular telegraph relay and a special telephone an operator may by manipulating a key operate the relay and its sounder without producing a sound in the telephone as the make and breaks of the key are far below the limit of audibility. But if though the same circuit by means of another key suitably connected there sent the rapid changes in current from an induction coil it will cause a series of loud clicks in the telephone corresponding to the signals transmitted but this current is too weak to affect the telegraph relay. It will be seen therefore that this method of duplexing is practiced not by varying the strength or polarity but by sending two kinds of current over the wire. Thus two sets of Morse signals can be transmitted by two operators over one line at the same time without interfering with each other and not only between terminal offices but also between a terminal office and any intermediate office or between two intermediate offices alone. End of appendix.