OB, Ohio Brass 10 inch cobalt porcelain suspension with clevis. I assumed the space around the pin was to provide an extra layer of insulation between the porcelain and the metal pin. I could find nothing on this feature in the Patents I read.

I did a search on the US Pat number and was quite surprised to find that the Patent is for the glaze, not for the unusual arrangement around the pin. It was a good starting point to find other suspension related patents, like the introduction of a sacrificial electrode and its' purpose. The difference between a fog type, or anti-fog type as they are sometimes called and a suspension designed for DC current applications. Another link was to a three page Pat description as to why Locke had a better idea impregnating the glaze before firing with precision formed bits of ceramic to hold the cap and pin in place than what was currently being used.

Lots of big words and defiantly not for grade school readers. Even if you only understand a little bit, it opens your eyes that there is much more to a suspension than a piece of porcelain or glass with metal ends.