The application by engineer Herbert Akroyd Stuart. The introductory lines of the application: The patent deals with ignition of an explosive charge of combustible vapor or gas and air when a permanent ignitor (such as a continuous electric spark or a highly heated igniting chamber) is in communication with the interior of the cylinder, by first of all compressing the necessary quantity of air for the charge, and then introducing into this quantity of compressed air the necessary supply of combustible liquid vapor or gas to produce the explosive mixture.