It looks like an educational meter to me, the sort of thing you might find in a school lab. My guess would be 1930s-40s.
I can see a red wire at the back of the movement, the insulation composition would probably be a clue.
EDIT: Looking at the case construction, it's possible that it might have been cut down from a larger meter by an enterprising Physics master. A lot of school lab equipment was created by the schoolmasters in those days. No, from the later photos, that looks as if it was made for the purpose.