Glen, top picture is a 1959 Ariel Square 4 on a Watsonian sidecar. Engine is 1000cc 4 cylinder in a square format, two twin cylinder cranks geared together. Middle picture a 1950 Square 4 ( I have 2 of them) and bottom a 1938 600cc sidevalve single. I also have a 1935 600cc ohc Square 4 that I am restoring.