Examiner's copy of Thomas Edison's early patent for an "Improvement in Speaking-Telephones," no. 208,299, two pages, 7.25 x 11, patented on September 24, 1878. The text features Edison's name printed at the conclusion, and the reverse of the first page features a printed diagram with numerous ink insertions in another hand explaining Edison's improvement. In very good to fine condition, with light soiling, and tack and staple holes to the bottom edge. Accompanied by a copy of a 1991 letter to the consignor from the US Patent Office, allowing this to remain in his possession as it "was part of an abolished classification and may have been obtained through legitimate channels."
While Alexander Graham Bell is credited with inventing the telephone, it was largely Edison who invented a workable carbon grain 'transmitter' (i.e. microphone) that made the telephone commercially viable. The carbon microphone remained standard in telephony until the 1980s, and is still being produced.
