I have this silver mystery object which i can't figure out, it's round with a lever on the side which opens a "trapdoor" is the center which opens up downwards.
I think the hallmark says C. B. & sons, although i cannot find a exact match on this site or on the silvermakersmark site i think it might perhaps be Charles Boyton & Sons. the year letter is k for 1925. The side is marked 3029 Patent 558 or 358.
What was this used for? is it part of something or on its own?
THANKS.
![Image](https://www.925-1000.com/pics/Ximg.jpg)
![Image](https://www.925-1000.com/pics/Ximg.jpg)