. Collection of United States patents granted to Thomas A. Edison, 1869-1884 . 2 Sheets—Sheet 2 T. A. No. 227,679. Patented May 18, United States Patent Office. THOMAS A. EDISON, OF MENLO PARK, NEW SPECIFICATION forming part of Letters Patent No. 227,679, dated May 18, 1880. Application filed March 29, 1879. To all whom it may concern: Be it known that I, Thomas Alva Edison,of Menlo Park, in the State of New Jersey,have invented an Improvement in Phono-5 graphs, (Case No. 174,) of which the followingis a specification. In Letters Patent No. 200,521,
. Collection of United States patents granted to Thomas A. Edison, 1869-1884 . 2 Sheets—Sheet 2 T. A. No. 227,679. Patented May 18, United States Patent Office. THOMAS A. EDISON, OF MENLO PARK, NEW SPECIFICATION forming part of Letters Patent No. 227,679, dated May 18, 1880. Application filed March 29, 1879. To all whom it may concern: Be it known that I, Thomas Alva Edison,of Menlo Park, in the State of New Jersey,have invented an Improvement in Phono-5 graphs, (Case No. 174,) of which the followingis a specification. In Letters Patent No. 200,521, granted tome, a cylinder with a helical-grooved surfaceis revolved with its screw-shaft and moved 10 along endwise. Upon this cylinder there is asheet of foil or similar material, and the sameis indented by the action of a point moved bya diaphragm, and this foil forms a phonogramthat can be used to reproduce the original 15 sounds when moved in contact with a pointand diaphragm. In the said patent one ofthe points is shown as connected directly tothe diaphragm, and the other point is upon aspring. 20 My present invention relates to improve-ments upo
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