All thanks for trying to help me figure out what this is. It is not Hollow, but does have a concave depression in it that you can see from the Bottom and side pictures. It does not have a hole of any kind going through the middle of it. I also thought it might be a looking device so I tried using it to look at letters and it didn't work as that device.
Thanks again and any more suggestions?
Nice ID Steve, Glass insulator is what I thought it was when I first saw it, we find quite a few of them down here around old house sites. When you posted the link it solidified my hunch as to what it was... "D"
Thank you all for hounding this out. I will have to try and figure out what time frame it was produced from. This is my first insulator I found detecting. You never know what you will find next.
Ok, not quite solved the Glass thingy is actually a Lightning rod insulator Patented in Aug 26 1851 by George W. Otis. The particular one I found has no embossing. Glass Lightning Rod Insulators