title: John Marshall: the making of true spectacles.
abstract: In 1693 John Marshall of London devised a novel method of grinding batches of identical, good quality, lenses of a specified focal length. Its commendation by the Royal Society led to a trade war between Marshall and rivals in the Worshipful Company of Spectacle Makers. Despite initial opposition the method was rapidly adopted by London opticians and, though much modified, it forms the unrecognised basis of present day practice.
authors: Department of Science, Technology, and Working Life, National Museums of Scotland, Edinburgh.
authors: D J
authors: DJ
authors: Bryden
authors: D L
authors: DL
authors: Simms
mesh_terms: D005139:Eyeglasses / Q000266:history*; D049670:History, 17th Century; D006801:Humans; D006113:United Kingdom