This is such an odd piece and I cannot figure out what it is. It's made of brass and has some sort of iron object inside (rusted down and almost disintegrating). There is an anchor with a rope...military? I found along the Northern shores of Lake Michigan.
My first thought was that it looks to have bee attached to a flat surface.
Looks to be made of pot metal, so it likely had a utilitarian function.
Maybe a hinge post or the base of a wall sconce as MCL suggested.
It might have been some type of small light fixture on a boat it has the shape like a navigation light but it is too small for that I think, so maybe a light sconce for steps or something like that .