Updated 28-VI-2020
Mercury Vapour
Introduction
Mercury Pressure
Mercury Spectrum
Lamp Nomenclature
Timeline of Developments
Mercury Vapour
J.T. Way
Cooper-Hewitt
Küch and Retschinsky
MA Medium Pressure
MB High Pressure
MC Low Pressure
MD Water-Cooled
ME Super Pressure
UHP Ultra High Pressure
Mercury Vapour
Fluorescent Coated Lamps
Tungsten Ballasted Lamps
Lamp Electrodes
Additives to the Arc
Electrodeless Designs
Future Developments
Mercury Vapour
High Pressure Circuits
Low Pressure Circuits
Electronic Operation

Mercury Development Timeline

Presented below is a chronological listing of the key milestones that illustrate the development of the mercury vapour lamp. Also included are a number of commercial points and observations concerning product construction and marking, which are of value in determining the date of production of a particular lamp.

Certain milestones are documented in greater detail elsewhere on this site, and additonal information can be obtained by clicking on the titles of interest below.

1821 UK Humphry Davy Demonstration of the first mercury vapour arc lamp at the Royal Institution in London
1860 UK J.T. Way World's first installation of mercury arc lamps, on the Hammersmith Bridge in London
1901 USA Cooper-Hewitt Invention of vacuum-mercury vapour tube by Peter Cooper-Hewitt, New York.
1906 DE Siemens Invention of vacuum-mercury high pressure quartz lamp by Kuch and Retschinsky.
1931 UK Osram-GEC Invention of the modern unsaturate vapour mercury lamp, type Osira "MA" 400W.
1932 UK Osram-GEC World's first streetlighting with mercury lamps, on the Watford Road in London
1934 UK Osram-GEC Introduction of the 250W MA lamp
1934 USA GE Introduction of first American mercury vapour lamp, type "H-1", a copy of the 400W MA.
1935 NL Philips Invention of the super-pressure water cooled mercury capillary lamp, type "MD".
1936 UK BTH-Mazda Introduction of the 150W MA lamp
1936 UK Siemens Bros Invention of the self-ballasted mercury lamp with internal tungsten coil, type "MAT"
1936 NL Philips Invention of the modern high pressure quartz mercury lamp, type "MB"
1937 UK BTH-Mazda Invention of the molybdenum foil seal for carrying metal wires into a quartz vessel
1937 UK Osram-GEC Invention of the fluorescent mercury lamp, type "MAF"
1937 NL Philips Introduction of the first fluorescent mercury lamp with quartz arc tube, type "MBF".
1939 UK BTH & GEC Introduction of the 650W and 1000W MA lamps
1948 USA Westinghouse Introduction of the first commercial 400W quartz mercury lamp, type "E-H1"
1950 USA Westinghouse Invention of colour improved lamp /C, with Magnesium Fluoro-Germanate phosphor
1952 USA Westinghouse Introduction of BT-37 envelope in USA, to lower bulb temperature for phosphor coatings
1955 USA GE Invention of 'Ballastless' mercury streetlighting lamps, for constant current series circuits
1955 USA GE Introduction of the 100W quartz mercury lamp in USA, type "H-4" with PS-25 bulb shape
1957 USA Westinghouse Invention of Caution Yellow lamps, with MFG phosphor and external yellow laquer.
1958 USA GE First use of oxide cathodes in USA for improved lumen maintenance (Bonus-Line).
1958 USA Westinghouse Launch of Westinghouse Weather-Duty brand for its lamps having hard glass envelopes
1960 USA GE The American H-4 100W lamp changed from a PS-25 to BT-25 bulb shape.
1960 USA GE Improvement of caution yellow lamps by application of a durable sprayed ceramic glaze
1960 USA GE Launch of Bonus-Line electrodes with improved life. First model was 400W BT37.
1960 USA GTE Sylvania Invention of Truetone Deluxe colour /X, with MFG phosphor and purple laquer.
1960-1 USA GTE Sylvania Launch of the Sylvania Banner brand, as a competitor to GE Bonus Line electrodes.
1961 USA GE Bonus Line technology extended throughout the popular range, superseding older types
1961 USA Westinghouse Launch of Westinghouse Lifeguard brand, superseding the former Weather-Duty name.
1963 USA GTE Sylvania Discontinuation of the Banner brand name, new electrodes for all standard types.
1963 USA GTE Sylvania Invention of /RS rough service lamps with stamped girder frame for 100 to 1000W
1963 USA GTE Sylvania Redesign of etch for Sylvania lamps featuring wattage rating in extra-large font
1964 USA GTE Sylvania Invention of Deluxe White /DX lamps, with europium activated yttrium vanadate.
1964 USA All Discontinuation of Purple stained /X lamps, superseded by the newer /DX types.
1965 USA GE Adoption of Sylvania Yttrium Vanadate phosphor and introduction of GE /DX lamps.
1966 USA GE Introduction of simplified European ED shape bulbs in USA, initally by General Electric
1966 USA GE Discontinuation of the GE Bonus Line brand name
1968 USA GTE Sylvania Discontinuation of /RS suffix on flat-frame lamps, which became standard construction.
1968-71 USA GTE Sylvania Introduction of /WDX Warm Deluxe lamps with incandescent-like 3300K colour.
1971 USA GE Introduction of /WDX Warm Deluxe lamps with incandescent-like 3300K colour.
1971 USA All Last known listing of Caution Yellow mercury - superseded by HPS.
1972-3 USA Westinghouse Introduction of full-coat BT bulbs, but quickly returned to clear end due to life reduction.
1975 USA Westinghouse Re-introduction of fully coated BT shape bulbs after improving phosphor adhesion.
1975 USA GTE Sylvania Introduction (approximate) of fully coated BT shape bulbs for fluorescent lamps
1975 USA GTE Sylvania Discontinuation of /RS girder frame in USA, but continued in Canada and EU until c.1985
1975-6 USA GTE Sylvania Introduction of /N Natural lamps in 175, 250, 400W to replace former /WDX colour.
1976 USA GTE Sylvania Discontinuation of Warm Deluxe /WDX lamps.
1977 USA GTE Sylvania Addition of 100W mogul-based /N colour lamp.
1977 USA GTE Sylvania Introduction of BT shape fluorescent lamps having clear band in the coating.
1978-80 USA GTE Sylvania Addition of 100W medium-based /N colour lamp having A-23 bulb.
1979-80 USA GTE Sylvania /N lamps were redesigned with addition of YAG phosphor, notable boost in lumens.
1979 USA GTE Sylvania Introduction of BT shape fluorescent lamps having full coating.
1980 USA GTE Sylvania Discontinued the 50W lamp rating. From 1982 the 40W was re-rated 40/50W
1980-2 USA GTE Sylvania The 100W medium based lamp changed from A-23 to E-17 bulb shape.
1980-2 USA GTE Sylvania The 100W mogul lamp changed from BT-25 to ED-23½ bulb shape.
1980-2 USA GTE Sylvania The 100W medium lamp changed from B-21 to B-17 bulb shape.
1978-80 USA GTE Sylvania Addition of 75W medium-based /N colour lamp having E-17 bulb.
1982-4 USA GTE Sylvania The 700W BT-46 lamps were discontinued.
1982-4 USA GTE Sylvania /N lamps were redesigned to improve colour, but with notable drop in luminous flux.
1984-6 USA GTE Sylvania The 50, 75 and 100W medium lamps changed from B-17 to ED-17 bulb shape.
1988 USA Philips Introduction of ED bulb shapes, superseding the former Westinghouse BT design
1988-92 USA GTE Sylvania The 100W mogul lamp changed from ED-23½ to ET-23½ bulb shape.
1989 USA Philips Discontinuation of Lifeguard brand name