Here's something I scratched up, a white glazed something or other marked PEIRCE on one end and an H in a shield on the other. Measures 2-3/4" wide x 2-7/8" long x 1-5/8" high. Looks like it was made to fit into a track of some sort. I haven't a clue as to what it's purpose was, any takers out there? Thanks to the following response from Denley Bryson: Its a insulator that holds cable. It slides on a steel peg that slides on a main frame. Also from Lou Hall: The is the insulator from an underground cable rack. And from Rick Soller: Your weird Peirce porcelain insulator is used on a rack in an underground tunnel......heavy cable is laid on the piece. Thanks to all.