Kinda looks like a glass piano insulator - usually come in pairs. Edit: Found this tidbit in an internet article - (assuming it's true) "I had always assumed that you put these under the castors of pianos or other heavy furniture, just to avoid making big dents in the carpet but....... I've just read the reason why they are called insulators, and it wasn't anything to do with with the carpets. Apparently the Victorians were obsessed with home entertainment, of which playing the piano was perhaps the most popular pastime. These glass cups, were introduced to insulate/deaden/suppress the sound of the piano when played."
Hi, The reason these were used was to keep the metal castors from leaving rust marks on the rug. The high humidity(no ac) then kept the carpets damp and any metal would rust over time. I have some from 4" wide down to an inch wide. the glass balls on the bottom of piand stools did the same thing. greg
Neat to know, Greg. I had some green ones before but never realized what they were. Think this one is antique?
Hi dude, I have never seen one with a patterned bottom all of mine dated between 1915 and 1940. They all had smooth bottoms. I have had them in green, clear and brown. Some had makers marks like AH, H and F. greg
The larger diameter ones with the smooth bottoms are "furniture coasters" allowing one to slide their furniture around and not scratching wooden floors or snagging on carpets. Like these:
Given the patterned bottom, could it be something other than a piano insulator? It kind of reminds me of this ink bottle:
