It looks like the needle is actuated by the brass bellows? Measuring atmospheric pressure?
I don't see any wires or whatever, to be electrical? Any wires or hook ups on the back?
Interesting to me, because I dug some rotted thin brass bellows about that diameter in a field that has dozens of items from early/mid 1700s to around 1840....but the bellows seemed "out of place" in this field. But mine are so rotted away, I think they must be quite old, if other brass things I find are not eaten up as badly.