[PT032ABR], Patent Application, Thomas Alva Edison, February 9th, 1889



Abandoned Case 819 Phonographs, good example of how Edison pays attention to cost: "I have found it desirable tomount the vertical shaft of the motor which drives my Phonograph upon a jewel step for which purpose I have heretofore used agate, but I have found that the agate wears away rapidly and that a harder jewel is required for the purpose. I now employ sapphire for that purpose. In my first uses of sapphire I selected pieces of sufficiently large size and had them ground into shape to fit the cup on the end of the steel pin which carried the stop, but the jewel formed in this way was exceedingly expensive since not only did it require f jewel of considerable size but the grinding of the sapphire into the shape necessary to fit the cup in the steell pin was an exceedingly expensive operation.##The object of my Invention is to provide a means for mounting a jewel upon the stop which will enable me to use an expensive jewel like sapphire without materially increaseing the cost of the machine. This I accomplish by taking small and irregularly shaped sapphires which would not be suiable for grinding to fit the cup in the end of the steel pin and be setting such sapphires into the cup of the steel stop by imbedding them in a suitable scement placed in such cup, such as oxy-chloride of zince or magnesium, taking care that the jewel projects at the center of the cup above the edges of the cup. After the cement has thoroughly set so that the jewel is held firmly in place, the jewel is held against a suitable grinding implement and its face ground off so as to leave a smooth surface at the center of the cup. The shapt of the motor being held against lateral motion by a suitable bushing and being pointed on its end, it rests only upon the center of the jewel or approximately its center, so that as long sa the jewel is ground smooth at the center of the cup it becomes immaterial whether it fills the rest of the cup or whether the rest of its surface is smooth or irregular. In this way an exceedingly cheap construction is produced employing cheap sizes and forms of the jewel and requiring very little in manipulation [description of drawing follows and then two claims]







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[PT032ABR], Patent Application, Thomas Alva Edison, February 9th, 1889

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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University

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