Based on your description—hardwood, brass plates, a heavy iron chain, and hollow inside—there are several possibilities, but I can’t identify it reliably without seeing it.
Could you upload a few photos? The most helpful would be:
- The entire object
- A close-up of the brass plates
- The opening that shows the hollow interior
- The chain and how it’s attached
- The bottom or any markings, stamps, or labels
From your description alone, it could be something like:
- An antique counterweight or hanging weight from a clock or pulley system.
- A decorative lantern or candle holder with a suspension chain.
- Part of an old lighting fixture (such as a hanging oil lamp or chandelier component).
- A vintage container or case designed to conceal a weight or mechanism.
A photo will make identification much more accurate.