Original linen-backed patent lithograph for the British Thomson-Houston Company's invention of a loud speaker, one page, 12.5 x 10.25, August 11, 1932. The diagram features multiple views of the auditorium-oriented loud speaker, which expands from a portable chest. The top border reads: "378,371 Complete Specification." The lower border features the printed text: "Charles & Read Ltd. Photo-Litho." The left border reads: "This Drawing is a reproduction of the Original on a reduced scale." Includes the printed British "Patent Specification" document, three pages on two sheets, which describes the invention as "a high capacity loud speaker of the auditorium type which is readily portable." The specification sheet bears a "U.S. Patent Office Library" ink stamp on the first page. In fine condition.
