My Great-Grandma gave me this light bulb about 12 years ago before she passed. She had no idea what it was for either. The only numbers on it are 78540 which is located on the glass on one of the arms. And another number 66113 located on the copper part in the center of the bulb. There are also patent numbers Sep.5:11, Dec.30:13, June23:14, and Nov.30:15 located on the copper part in the center of the bulb also. If you have any idea what this thing is, please write back. Thank you!!
