I think this is possibly a 14HP Crossley radiator cap.The Dia. is 1-7/8". It has a 20TPI thread.The bakelite part is excellent, the base has a nick to one edge, but it should still screw onto a radiator.I can post this and I accept PayPal.
Broken down. Not working. Could bake a working engine from the 2. Found in grandfathers / uncles garage along with large amount of other de Dion parts..