'Auto-Thermos' pressure cooker of insulated cast aluminium, with lid secured by removeable yoke, with spring-loaded piston acting as pressure regulating and warning device, and with Easiwork pressure gauge, UK patent 291364 in 1929 by Camille Hautier of Boulogne, France, 1927-1935 Auto-Thermos' pressure cooker, c. 1930 1927-1935