The lens turned out to be made out of glowing uranium glass! It was marked "Fry Golden Glow" with a keystone logo. Most certainly the same Fry Glass out of Rochester, Pa. that manufactured the opal insulators. This type of lens was used in the early 1900's for both spotlights and locomotive headlights. The yellowish glow of light shining through the lens was thought to cut through fog better than clear light.