Embossed on the base CHICAGO INSULATING CO./ PAT OCT 16 1883. Skirt 3 dots in a triangle.

I am partial to insulators with lots of embossing but dislike the fact that it is on the bottom where it can not be seen. As much as I try to avoid base embossed pieces, I come across beauties like this full of impurities, another thing I am partial to, and they end up in the collection despite my best efforts.