A GE incandescent lamp for underwater use, circa 1957. [See GE 1957 catalog pp. 14, 21.] Catalog indicates that the unit's list price was $40, rated life was 50 hours, and it was designed "to withstand 300 lbs. of water pressure." Characteristics: Brass tube base (1.25" dia. x 6" L) originally made with a 3" rubber-coated cable lead. Lead on this unit has been cut to 1.25". Two 1/4" holes are punched near the bottom. C-5 tungsten filament with six upper and five lower supports. The ends of the filament are welded to the leads. Glass support-mount is attached to leads with two wires. Tungsten powder is loose in lamp to clean the inner lamp wall of tungsten boiled-off the filament. Tipless, G-25 envelope. The patent for the tungsten powder cleaning technique is US1809661, "Electric Lamp," issued to GE's Daniel K. Wright on 9 June 1931.
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