'Auto-Thermos' presure cooker, 1929.
© Science Museum / Science & Society Picture Library
The cooker is of insulated cast aluminium, with a lid secured by a removable yoke, and has an Easiwork presure gauge. A spring-loaded piston acts as a presure regulating and warning device. The cooker's airtight structure creates high presure and allows water to go beyond its boiling point. This leads to food cooking more quickly.