Original Edison pen and ink sketch of telegraph circuits

Edison, Thomas Alva, American inventor and businessman (1847-1931). Two original sketches. [With:] Autograph letter signed ("Thos. A. Edison").

€ 18,000.00

Two original Edison design sketches of a telegraph circuit, sent to Charles Sumners Wentworth with a letter (signed, and in Edison's own hand) discussing telegraph design: "Without I know what the resistance of your sounder is it would be hard to say how many cells would be required. I should think about 8 would do the business if they are 3 ohm sounders ..." Edison closes on a personal note: "I am married and have as the French say 'trois joli petite' infants".

Both sketches are pen and ink, with a ground line and "private line" labelled. Edison's intimate knowledge of the workings of telegraphs was spurred on by his interest in developing a telegraph cable capable of carrying more than one message at a time, which he and others recognized as an invention with great commercial appeal. This research on a multi-line telegraph, which culminated in the work of Antonio Meucci, Philipp Reis, Elisha Gray and Alexander Graham Bell, led to the invention of the telephone.

On Edison's 10 & 12 Ward St. letterhead stationery.