some type of insulator for a electrical system? On Mon, Apr 7, 2014 at 10:11 AM, Evans, Lynn (DNR) <[log in to unmask]>wrote: > Hello all - We have a mystery glass object, a thick, hollow disk, with the > center cut out. It is 4.75" in diameter; the slightly off-center hole is > 2.25" in diameter; the disk is about 2" deep. One side is flat, and has a > rectangular hole through it (1.75" x 1.5"). You can see an image at the > link below: > > www.flickr.com/photos/64404343@N02/13694786095/< > http://www.flickr.com/photos/64404343@N02/13694786095/> > > The object was found in a c.1910 dump on Mackinac Island, Michigan. > > Any suggestions? > > Lynn Evans > Mackinac State Historic Parks >