While black and white Schlieren photography had a long-standing tradition, innovations by the National Physical Laboratory on 16 mm equipment solved the challenges of incorporating color. The Shell Film Unit further refined the technique using 35 mm film. The Schlieren technique is a method of making visible any phenomenon where changes of refractive index occur in transparent solids, liquids or gases. For more information about Shell’s Historic Film Archive please contact: filmservices@shell.com #Shell #ShellFilmUnit #HistoricFilmArchive #Documentary #History #Engineering #Photography #Schlieren #16mm #35mm --- Shell’s surprising and captivating Historic Film Archive dates from 1934 and covers a rich mix of topics from technology, science and engineering to craftsmanship, motorsport and travelogue. The Shell Film Unit, responsible for the content, was a highly celebrated part of Britain’s Documentary Movement. Key figures from that movement were involved, including: Jack...