Jim Colburn sent me this photo of a UPW insulator in his collection. Union Porcelain Works started making electrical porcelain in the early 1880's. The green ink under-glaze logo consisting of the eagle with arrows in its beak was first used in 1877. Later the marking also included "U.P.W." above the eagle. We do not know when the insulator was made but would guess in the 1890's. Evidently UPW only used green ink. [id=250771028] [id=250771220] See the next link for more info on what is in the eagle's mouth: arrows? snake? or "S"? [id=250788306]