An interesting old C-clamp (or "cramp" as the British used to call them). Note that the screw turns through a piece that is riveted to the clamp body rather than cast or forged into it. Also, if the screw is fully closed, it does not touch the fixed jaw of the clamp so it couldn't be used for thinner materials. The fixed jaw is also serrated, giving a better grip but not a great idea for working on soft materials like wood. No maker's marks and no idea of its age.