Lewis .303 inch Mk I machine gun, 1915

This model of Lewis was used on aircraft during World War One (1914-1918). Its low weight and air-cooling system made it ideal for flying. It could be used as an observer or gunner's weapon mounted on a ring in the cockpit, or as a pilot's forward firing gun mounted on the wing above the propeller on single-engined fighters. This mounting was necessary as the Lewis could not be synchronised to fire through the propeller arc.