For pic go to:
http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00909m

If link doesn't work, it's a short lamp holder, bayonet mounted lamp on top (like for a Press 25 bulb), bakelite [?] base with 2 screws for attaching wires, I assume. Bulb is shaped like a short inverted cone (fat part on top.)

Well, the bulb is an old 6 volt automotive bulb and the socket (base) is a standard bakelite item from the 40-ish era. It isn't anything that would specifically relate to photography. It may have been something a previous owner had used for flash/battery test purposes. Just ordinary hardware store items, I'm afraid.

Thanks Glenn. That seems to be the consensus over at photo.net as well. You've saved me the trouble of going on 'Antiques Road Show.'

Oddly enough I found the identical socket in one of my kits too.

Other than a bare bulb extension flash, I can't think of anything to use them for.