What the heck is this?

We had a guy in Macon that was in business since the late 40s after he got back from the war. He was a good friend of Daddy's. Wiley Williams was his name and he owned Wiley Williams Glass Company. Daddy got him to make a couple of glass tops for some barrel tables that Kitty and I still have today. I was just a kid, but I watched him do it in the front yard. He had a glass cutter almost exactly like the one above that attached to an adjustable arm with a suction cup on the end. He took that arm, suctioned it to a large square piece of glass and cut two perfectly sized round glass table tops in less than a minute a piece. That old guy really knew how to do it. It takes skill for sure.