Experimental notes, working papers, correspondence and lecture summaries compiled by Charles Wheatstone, 1836-1875, and photographs collected by him in that period. Notably including papers relating to the development and testing of the telegraph, [1836-1960]; descriptions of experiments and test results concerning the measurement of electromotive forces and electrical potential, [1840-1875]; experimental observations on the nature of magnetism, electricity and thermodynamics, including electromagnet design, batteries and dynamos, [1834-1855]; working papers relating to optics including experiments into refraction, colouration of compounds and polarisation, [1850-1875]; drafts of lectures on sound and musical instruments prepared by Wheatstone, [1832-1837]; material relating to the management of the Wheatstone collection of scientific instruments and library, 1890-1992; biographical material relating to the life of Wheatstone, the invention of the telegraph and Wheatstone's musical instrument manufacturing business, with unrelated newspapers, 1757-1975; stereoscopic photographs and glass negatives taken by Roger Fenton, Samuel Buckle, Jules Duboscq and others, featuring landscapes, still lifes, panoramic scenes of cities including Paris and Moscow and the interior and exterior of the Crystal Palace, Hyde Park, Sydenham, 1851, and especially the Exposition Universelle, Paris, 1855, [1850-1901]; artefacts from Department of Physics, King's College London, including demonstration equipment, telegraph apparatus, a nail fiddle and other prototype musical instruments, [1834-1875]; exhibition of scientific and musical instruments, [1834-1875].