I can't recall seeing patents on any Embury tubular until the Air Pilot came out which had some patent numbers at the base of the tube. The 240 Supreme was one of the Embury No.2 CB's that switched to the Defiance bail in 1930. The question in dating those before 1930 is: when did they change the plain bail to the socket flange bail? I agree with Phil that it was probably around 1924-1925. The socket flange was a 1910 Dietz patent that typically would have run-out after 14 years - or 1924. It appears that Paulls also adopted the socket flange on their lanterns around the same time. BB