[Reece]

The connector shown on the unit is probably original and is called a plug cap. It would have been plugged into a plug body, which is the adapter having an Edison thread for a lamp socket, and a two-prong outlet for the plug cap. Many homes did not have any or many base receptacles in those days, and connections had to be made to drop light sockets. Where base receptacles were available, the plug body was removed. The tubes in question were used in the twenties in consumer radios but not afterwards, so this device was probably boxed up some time after that and never used again. There are instructions on line for rejuvenating tubes with thoriated filaments by other means, of interest to us today since those tubes become more rare every day.