These experiments of 1875, as recorded in Edison's famous note-books, show that in that year he detected and studied some then unknown and curious phenomena which made him think he was on the trail of a new force. His representative, Mr. Batchelor, showed these experiments with Edison's apparatus, including the "dark box," at the Paris Exposition in 1881. Without knowing it, for he was far in advance of the time, Edison had really entered upon the path of long-distance wireless telegraphy, as was proven later when the magnificent work of Hertz was published. When Roentgen made the discovery of the X-ray in 1895 Edison took up experimentation with it on a large scale. He made the first fluoroscope, using tungstate of calcium for the screen. In order to find other fluorescent substances he set four men to work and thus collected upward of eight thousand different crystals of various chemical combinations, of which about eighteen hundred would fluoresce to the X-ray. He also invented a new lamp for giving light by means of these fluorescent crystals fused to the inside of the glass. Some of these lamps were made and used for a time, but he gave up the idea when the dangerous nature of the X-ray became known. It would be possible to go on and describe in brief detail many more of the hundreds of Edison's miscellaneous inventions, but the limits of our space will not permit more than the mere mention of a _few_, simply to illustrate the wide range of his ideas and work. For instance: A dry process of separating placer gold; the rapid disposal of heavy snows in cities. Experiments on flying machines with an engine operated by explosions of guncotton. The joint invention, with M. W. Scott Sims, of a dirigible submarine torpedo operated by electricity. Pyromagnetic generators for generating electricity directly from the combustion of coal. Pyromagnetic motors operated by alternate heating and cooling. A magnetic bridge for testing the magnetic qualities of iron. A "dead-beat" galvanometer without coils or magnetic needle. The odoroscope, for measuring odors; preserving fruit _in vacuo_; making plate glass; drawing wire. Metallurgical processes for treatment of nickel, gold, and copper ores. From first to last Edison has filed in the United States Patent Office more than fourteen hundred applications for patents. Besides, he filed some one hundred and twenty caveats, embracing not less than fifteen hundred additional inventions. The caveat has now been abolished in patent-office practice, but such a document could formerly be filed by an inventor to obtain a partial protection for a year while completing his invention. As an example of Edison's fertility and the endless variety of subjects engaging his attention the following list of matters covered by _one_ of his caveats is given. All his caveats are not quite so full of "plums," but this is certainly a wonder: