Have you figured out what they are yet?
They could hang in a tree, be found on the porch, or sit on a table in the house.
They are fly/insect traps.
The genius is their simplicity, extremely useful for catching the pests, practical because they can be used anywhere, and when displayed in an area with the light shining through they are attractive.
The fly,bee, or any flying insect attracted to sweet nectar, will enter at the bottom hole, and the hole is just the right size so that you wouldn't catch larger bugs such as moths. They will then drink from the liquid in the bottom well. When they decide to leave apparently they only fly sideways and upward, not downward, and not back the way they came in through the bottom. Doom
The photos above show the bottle shaped traps which are from the 1900's. Earlier forms are usually in two pieces and shaped differently. In the early 1900s, there were many "bottle" fly traps that were apparently made from bottle molds. These pieces have definite mold marks, molded lips and simply appear to be bottles with the bottom pushed in.
These are still being made today because of the genius and simplicity involved. Only experience in recognizing the difference in old versus new glass can help you determine if you have found an antique bottle or a brand new version. You will usually not find a new one that is hand blown but that doesn't mean they are not out there.
For some history -- Many of the Victorian fly traps (1890's) were either blown by art glass makers or they were two-piece pressed glass contraptions.
|An older blown glass fly trap. Note the blown glass stopper.|
|Close up of fly finial.|
|Pressed glass fly trap with fly
|The "Unique Fly Trap" has a 1914 patent date, an inserted fly screen cone and a tin lid. This is a blown-molded piece and some examples do not have the patent day, just Pat. Appl'd.|
So, the next time a fly is in your house, you might wish you had one of these on a table to attact it, instead of running around with a fly swatter trying to get it.