Excuse the crappy cell phone pic but didn't have my real camera with me. Any idea of what this is? It is threadless and has a white glaze on it. They are quite big maybe 8 x 6 inces. Had a # engraved in them 1842xx. The story I was told was it was from the first house to get electric in the area. They were supposedly hand made. Are they really Insulators? Or what are they?