What Is It? – October/November 2011

John Deman of Bath, Ont., sent along photos of this item that he picked up at an estate auction about four years ago; no one seemed to know what it was. It measures 101⁄ 2 inches in height and is 41⁄ 2 inches wide. Its base is metal while many of the cogs appear to be made of brass, and there is a 11⁄ 4 inch hole through the base. Can anyone help John solve this mystery?