Bart Senior wrote:
Not a cup.

I think it is a lamp where small bits of animal
fat were burned to provide light.


Certainly possible... think how far a step it is from an animal fat lamp
to a Fresnel lens...

Not trying to challenge you, why is it not a cup? Looks like it would
make a good drinking vessel... a bit on the smallish side...

BTW thanks for the links Gilligan. Very interesting reading.

Regards
Doug King