Large original British linen-backed patent lithograph for Thomas Edison's 'improvements in circuits and instruments for chemical telegraphs,' one page, 21 x 15, February 27, 1873. The diagram features several figures showing Edison's improved circuitry for long-distance telegraph lines, with one figure tracing a route through the American northeast. The top border reads: "A.D. 1873. Feb. 27. No. 735. Edison's Specification." The lower border reads: "The filed drawing is not colored. Drawn on Stone by Malby & Sons. London, Printed by George Edward Eyre and William Spottiswoode, Printers to the Queen's most Excellent Majesty, 1872." In fine condition, with losses to the blank top edge.
