. Collection of United States patents granted to Thomas A. Edison, 1869-1884 . (No Model.) T. A. for Telegraphs. No. 239,154. Patented March 22, attest; y?. -ZT o£ c s o , PHOTO-LITHOGRAPHER, WASHINGTON, 0 C United States Patent Office. THOMAS A. EDISON, OF MENLO PAEK. NEW FOR TELEGRAPHS. SPECIFICATION forming part of Letters Patent No. 239,154, dated March 22, 1881. Application filerl December 14, 1880. (No model.) To all whom it may concern: Be it known that I, Thomas A. Edison, ofMenlo Park, in the county, of Middlesex andState of New Jersey, have in
. Collection of United States patents granted to Thomas A. Edison, 1869-1884 . (No Model.) T. A. for Telegraphs. No. 239,154. Patented March 22, attest; y?. -ZT o£ c s o , PHOTO-LITHOGRAPHER, WASHINGTON, 0 C United States Patent Office. THOMAS A. EDISON, OF MENLO PAEK. NEW FOR TELEGRAPHS. SPECIFICATION forming part of Letters Patent No. 239,154, dated March 22, 1881. Application filerl December 14, 1880. (No model.) To all whom it may concern: Be it known that I, Thomas A. Edison, ofMenlo Park, in the county, of Middlesex andState of New Jersey, have invented a new and 5 useful Improvement in Telegraph Apparatus;and I do hereby declare that the following isa full and exact description of the same, refer-ence being had to the accompanying drawing,and to the letters of reference marked thereon. o The object of this invention is to provide arelay for telegraph-lines, in which a sounder orother electrical apparatus in a secondary orlocal circuit shall be controlled by varyingthe resistance therein ; and my arrangement 5 for this purpose consists in a local circuit con-taining such a resistance as shall decrea
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Keywords: ., boo, bookcentury1800, booksubjectinventions, booksubjecttelephone
