Helen Sharman OBE, from Sheffield and a former University of Sheffield-educated chemist who developed chocolate for Mars, was the first Briton in space on the Soyuz TM-12 mission on 18 May 1991, aged 27 (she is still the fifth-youngest person to have flown into space), landing with Soyuz TM-11 eight days later. David Mellor of Sheffield produced the standard design for street furniture, including traffic lights, in the UK from 1973. The US had installed its first electric traffic lights in August 1914 in Cleveland, and traffic lights were first introduced permanently in the UK on 16 March 1928 in Leeds at the junction of Park Row, Leeds and Bond Street, although were not vehicle-actuated; there had been a one-day trial of traffic lights in Wolverhampton on 11 February 1928. John Harrison of Barrow upon Humber (but born in Yorkshire at Foulby), invented the marine chronometer which allowed longitude to be accurately measured, and hence navigation at sea. This allowed Captain James Cook of Whitby to colonise much of Australia. Harrison also invented the bimetallic strip and the rolling bearing, without which most vehicles could not move. Albert Crewe, born near Huddersfield in 1927 and attended grammar school in Bradford, invented the scanning electron microscope in 1970 at the Argonne National Laboratory (US). John Carbutt (1832–1905), from Sheffield and moved to America, founded his Keystone Dry Plate Works in 1879 and was the first to develop sheets of celluloid coated with photographic emulsion for making films in 1888, and for William Kennedy Dickson's Kinetoscope around 1890, which set the 35mm standard for motion and still cameras. Roundhay Garden Scene, shot on 14 October 1888 by Louis Le Prince, is the oldest surviving film in existence; 'talking' movies appeared after 1927. Dennis Taylor of T. Cooke & Sons of York invented the Cooke triplet in 1893 to stop optical aberration, and allow fine definition up to the outer edge of lenses. Prof Sir George William Gray developed LCD displays at Hull, when working for the MoD (RRE) in Malvern, developing it with the substance cyano-biphenyl in 1973; the VFD (a similar purpose) was invented in Japan in 1967. Smithson Tennant born Selby, educated in Beverley, discovered osmium and iridium in 1803; the two are atomic numbers 76 and 77, with osmium being the densest naturally occurring element, and iridium is the next densest.