Edison, His Life and Inventions [225]
at the Philadelphia Exhibition of 1884. It became known in scientific parlance as the "Edison effect," showing a curious current condition or discharge in the vacuum of the bulb. It has since been employed by Fleming in England and De Forest in this country, and others, as the basis for wireless-telegraph apparatus. It is in reality a minute rectifier of alternating current, and analogous to those which have since been made on a large scale.
When Roentgen came forward with his discovery of the new "X"-ray in 1895, Edison was ready for it, and took up experimentation with it on a large scale; some of his work being recorded in an article in the Century Magazine of May, 1896, where a great deal of data may be found. Edison says with regard to this work: "When the X-ray came up, I made the first fluoroscope, using tungstate of calcium. I also found that this tungstate could be put into a vacuum chamber of glass and fused to the inner walls of the chamber; and if the X-ray electrodes were let into the glass chamber and a proper vacuum was attained, you could get a fluorescent lamp of several candle-power. I started in to make a number of these lamps, but I soon found that the X-ray had affected poisonously my assistant, Mr. Dally, so that his hair came out and his flesh commenced to ulcerate. I then concluded it would not do, and that it would not be a very popular kind of light; so I dropped it.
"At the time I selected tungstate of calcium because it was so fluorescent, I set four men to making all kinds of chemical combinations, and thus collected upward of 8000 different crystals of various chemical combinations, discovering several hundred different sub- stances which would fluoresce to the X-ray. So far little had come of X-ray work, but it added another letter to the scientific alphabet. I don't know any thing about radium, and I have lots of company." The Electrical Engineer of June 3, 1896, contains a photograph of Mr. Edison taken by the light of one of his fluorescent lamps. The same journal in its issue of April 1, 1896, shows an Edison fluoroscope in use by an observer, in the now familiar and universal form somewhat like a stereoscope. This apparatus as invented by Edison consists of a flaring box, curved at one end to fit closely over the forehead and eyes, while the other end of the box is closed by a paste- board cover. On the inside of this is spread a layer of tungstate of calcium. By placing the object to be observed, such as the hand, between the vacuum-tube and the fluorescent screen, the "shadow" is formed on the screen and can be observed at leisure. The apparatus has proved invaluable in surgery and has become an accepted part of the equipment of modern surgery. In 1896, at the Electrical Exhibition in the Grand Central Palace, New York City, given under the auspices of the National Electric Light Association, thousands and thousands of persons with the use of this apparatus in Edison's personal exhibit were enabled to see their own bones; and the resultant public sensation was great. Mr. Mallory tells a characteristic story of Edison's own share in the memorable exhibit: "The exhibit was announced for opening on Monday. On the preceding Friday all the apparatus, which included a large induction-coil, was shipped from Orange to New York, and on Saturday afternoon Edison, accompanied by Fred Ott, one of his assistants, and myself, went over to install it so as to have it ready for Monday morning. Had everything been normal, a few hours would have sufficed for completion of the work, but on coming to test the big coil, it was found to be absolutely out of commission, having been so seriously injured as to necessitate its entire rewinding. It being summer-time, all the machine shops were closed until Monday morning, and there were several miles of wire to be wound on the coil. Edison would not consider a postponement of the exhibition, so there was nothing to do but go to work and wind it by hand. We managed to find a lathe, but there was no power; so each of us, including Edison, took turns revolving
When Roentgen came forward with his discovery of the new "X"-ray in 1895, Edison was ready for it, and took up experimentation with it on a large scale; some of his work being recorded in an article in the Century Magazine of May, 1896, where a great deal of data may be found. Edison says with regard to this work: "When the X-ray came up, I made the first fluoroscope, using tungstate of calcium. I also found that this tungstate could be put into a vacuum chamber of glass and fused to the inner walls of the chamber; and if the X-ray electrodes were let into the glass chamber and a proper vacuum was attained, you could get a fluorescent lamp of several candle-power. I started in to make a number of these lamps, but I soon found that the X-ray had affected poisonously my assistant, Mr. Dally, so that his hair came out and his flesh commenced to ulcerate. I then concluded it would not do, and that it would not be a very popular kind of light; so I dropped it.
"At the time I selected tungstate of calcium because it was so fluorescent, I set four men to making all kinds of chemical combinations, and thus collected upward of 8000 different crystals of various chemical combinations, discovering several hundred different sub- stances which would fluoresce to the X-ray. So far little had come of X-ray work, but it added another letter to the scientific alphabet. I don't know any thing about radium, and I have lots of company." The Electrical Engineer of June 3, 1896, contains a photograph of Mr. Edison taken by the light of one of his fluorescent lamps. The same journal in its issue of April 1, 1896, shows an Edison fluoroscope in use by an observer, in the now familiar and universal form somewhat like a stereoscope. This apparatus as invented by Edison consists of a flaring box, curved at one end to fit closely over the forehead and eyes, while the other end of the box is closed by a paste- board cover. On the inside of this is spread a layer of tungstate of calcium. By placing the object to be observed, such as the hand, between the vacuum-tube and the fluorescent screen, the "shadow" is formed on the screen and can be observed at leisure. The apparatus has proved invaluable in surgery and has become an accepted part of the equipment of modern surgery. In 1896, at the Electrical Exhibition in the Grand Central Palace, New York City, given under the auspices of the National Electric Light Association, thousands and thousands of persons with the use of this apparatus in Edison's personal exhibit were enabled to see their own bones; and the resultant public sensation was great. Mr. Mallory tells a characteristic story of Edison's own share in the memorable exhibit: "The exhibit was announced for opening on Monday. On the preceding Friday all the apparatus, which included a large induction-coil, was shipped from Orange to New York, and on Saturday afternoon Edison, accompanied by Fred Ott, one of his assistants, and myself, went over to install it so as to have it ready for Monday morning. Had everything been normal, a few hours would have sufficed for completion of the work, but on coming to test the big coil, it was found to be absolutely out of commission, having been so seriously injured as to necessitate its entire rewinding. It being summer-time, all the machine shops were closed until Monday morning, and there were several miles of wire to be wound on the coil. Edison would not consider a postponement of the exhibition, so there was nothing to do but go to work and wind it by hand. We managed to find a lathe, but there was no power; so each of us, including Edison, took turns revolving