Faraday's calculator. View of a cylindrical slide rule once owned by British scientist Michael Faraday (1791-1867). This is a very early example of a Fuller slide rule, made by W.F. Stanley in the mid-19th century. Conventional slide rules needed to be ever larger to gain improved precision. One idea was to wrap the scale of the slide rule in a helical pattern around a cylinder. This item is preserved at the Royal Institution, London.