A hit-an-miss engine is a type of four-stroke internal combustion engine that was conceived in the late 1800s and was produced by various companies from the 1890s through approximately the 1930s. The name comes from the method of speed control that is implemented on these engines (as opposed to the "throttle governed" method of speed control). The sound made when the engine is running is a distinctive "POP whoosh whoosh whoosh whoosh POP" as the engine fires and then coasts until the speed decreases and needs to fire again to maintain its average speed.