I just got this from Michał Okulicz in Poland, a photo of a Cmielow fuse holder.

This is nearly identical to the unmarked "Strange" Russian insulator shown here: [id=262656235]

Here is his explanation:

Hello.

Your insulator probably was made in Poland by Cmielow's factory.

My one was made between 1918 - 1930's (because logo is green and big).

That type of insulators was used like fuses. Special wire was assembled between two copper screws (contacts). Upper triangle was a wire holder, and when the fuse was burning, metal drops fell down on trangle's arms.

Michal.