Negretti & Zambra (London) Graphoscope (apparatus for stereoscopic views), c. 1870. walnut. Slide base, topped by a frosted glass, a magnifying glass and two stereoscopic lenses. Manufacturer's plate inlaid in the wood. 32 x 17 x 6 cmNegretti & Zambra (London) Graphoscope (stereoscopic views), c. 1870. Walnut. Sliding base with frosted glass, magnifying glass and two stereoscopic lenses. Manufacturer's plate in the wood. 32 x 17 x 6 cm