An odd shaped light bulb

[VacuumTubesHunter]

Hi All!

I have recently acquired what looks like a typical clear 100 W bulb, but with two parallel 'arms'.



More pictures are visible here:
http://www.lampes-et-tubes.info/u1.htm

The original box contained 3 identical bulbs.
Exterior print faded, but can make out 'Union Carbide Corporation', ( ? ) Division.
Also numerals, as close as I can decipher of 158810. Qnty 3.

Therefore, this oddly shaped light bulb was not some unique experiment, but a manufactured product.

Any clue about this lamp is welcome!

Giorgio Basile
Belgium

[Justin]

Are those "arms" sealed at the ends?   It seems as an attempt as an evecuation point.  Sorry this an old topic.