Hey You Guys,
There's been a trail of these with no denouement...
Hopefully, I can bring a degree of closure on these. I've found a number of the ones like yours over the years. I always wondered what they were. I thought some sort of plug or stopper for vitreous clay pipe, and I still hold on to that as a possibility. Only because I have found them in close proximity to small size vitreous pipe.
I was later told that they were stoppers for carboys. That made sense to me, but I wondered about alternative or additional uses...
It wasn't until I found this porcelain example that I pretty much closed the book on them.
The Gem Stopper Co, of Philadelphia patented these guys, though I've not yet found the patent drawings. The Smithsonian has their catalog:
[Trade catalogs from Gem Stopper Co.] | Collections Search Center, Smithsonian Institution
"[Trade catalogs from Gem Stopper Co.]
VARIANT COMPANY NAME:
Established 1875
COMPANY NAME:
Gem Stopper Co.
RELATED COMPANIES:
Gesco
NOTES CONTENT:
Universal acid carbon stoppers ; asbestos gaskets ; metal fasteners ; "Gesco" brand."
~~~~~~~~~~~~~~~~~
From a lawsuit concerning their milk bottle stoppers:
"That at all said times, the Gem Stopper Company, the defendant above named, was and now is a Pennsylvania corporation engaged in the business of the manufacture of bottle stoppers, including tin milk tops, and a special variety thereof known as Lightning Tin Tops for milk bottles and the wire trimmings for fastening the same.
Bradbury's Lawyers' Manual and Clerks' and Conveyancers' Assistant
These stoppers, I believe were afixed with wire bail closures, a la the Lightning stopper bail. I also think for that nice tight seal, they would have had a rubber gasket.
I hope this will serve as a semi solution to some of the long running discussions that have periodically graced these forums.