This U-266 is probably a Illinois Elect. Co. product made during their "Triangle M" marking phase, which was just after (or possible the two ran together a bit) they used the "MACOMB" marking. Appx 1915-1923. Notice the double rest? (The skirt and petticoat are both unglazed for firing) check this link for more info http://www.perceval2000.com/NNTriMinfopage.html