antique early electric lightning arrester Cook Electric Co, Chicago

Old early electric porcelain and brass lightning arrester made by Cook Electric Company - Chicago. It is marked -Arrester No 2- on the back of the porcelain.

This measures about 2 3/4" x 2 7/8" across the base and about 1 3/8" across the brass. There is an old chip to the porcelain which shows in the second photo.