Portable Light Co. U.S.A. No. fifteen movable arm spotlight - rotates in a circle and moves up and down on the post. About 7" across the face of the light and about 20" top to bottom. I wasn't sure if it was working so I took it to an electronics technician. He didn't have a bulb but tested it and found it was in good working order. He did notice the rubber gasket was bad around the glass so he replaced that. The up and down and rotate mechanism is very smooth. I know it came off a boat but I don't know what kind. I am guessing 1950's but it could be much earlier. Portable Light Co. trade catalogs are available on-line which could help narrow it down. The company made powerful spot and searchlights for marine craft as well as emergency vehicles and fire trucks.