SE—L Historical Society Museum — Lighting : A sample of some lighting devices at our museum.
Adult Text:
l—r Anthony Carlone, South Euclid Mayor George Urban, and Gordon Artress. They are likely discussing the benefits of the mercury vapor lamp at right versus the incandescent lamp.
"Seeable" light is measured in lumens. An incandescent lamp produces only about 20 lumens for each watt of electricity it consumes. The mercury vapor produces a bit over 50 so it's 2.5 times as bright for the same wattage. It does require an expensive ballast but it also lasts 20,000 hours (about 7 years at 8 hrs a day) versus the incandescent's 1,000 hours (4 months at 8 hours a day).
The white coating on the lamp is a phosphor, very much like the phosphor coating on fluorescent lamps, and it makes the light output whiter versus the bluish tinge the lamp would have without it.
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