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French Auer type O.R. Tungsten Filament
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This lamp of unusual construction has proven difficult to identify, in view of it being incorrectly described in various books as having an osmium filament. Its true design and application have been identified by studying the patents and advertisements of its manufacturer, referenced at the foot of this page. In fact, despite its primitive-looking construction, it is actually a relatively modern drawn tungsten lamp. It is a development of the French subsidiary of the Auer Company.
Due to the novel filament mounting shape, it radiates its light uniformly in all directions. When hung from the ceiling it provides greater illuminance of horizontal surfaces than typical squirrel-cage metal filament lamps. Furthermore, the quantity of supports makes the filament less susceptible to sag, and the lamp can be burned in any position.
The filament is arranged in a large open spiral that makes 6½ revolutions around a central porcelain spine bearing 27 rigid nickel support wires. The end of each support is formed into a hook, into which a short length of refractory metal wire not much thicker than the filament is clamped. These thin wires, probably of platinum, iridium or molybdenum, minimise heat conduction losses from the filament. The filament is fixed to extremity of each support by a globule of molybdenum, obtained by deposting a paste of the powder of that metal in a binder of sugar syrup, and reducing the mass to a solid metal bead in a hydrogen furnace. The patent literature reveals that this construction was pioneered in the days of the sintered tungsten filament, but the commercial literature states that this lamp has a drawn tungsten filament - it is likely that its manufacture did not commence until after the 1909 introduction of drawn wire. |
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| Manufacturer: |
Société Française Auer |
| Lamp Power: |
~25 Watts |
| Lamp Voltage: |
115 Volts |
| Lamp Current: |
~0.22 Amperes |
| Cap Type: |
E27s |
Brass + Tall Vitrite |
| Bulb Type: |
SA-60 |
SA-19 in eighths/inch |
| Bulb Finish: |
Clear |
Soda-lime glass |
| Filament Type: |
26S-2R |
Ladder Spiral |
| Atmosphere: |
Vacuum |
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| Luminous Flux: |
30 Candles |
27.6 lumen/steradian |
| Luminous Efficacy: |
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| Beam Intensity: |
N/A |
| Beam Distribution: |
N/A |
| Colour Temperature & CRI: |
CCT: 2400K |
CRI: Ra 100 |
| Chromaticity Co-ordinates: |
CCx: 0.486 |
CCy: 0.415 |
| Rated Lifetime: |
1000 hours |
| Burning Position: |
Universal |
| Overall Length: |
165 mm |
6½ inches |
| Light Centre Length: |
102 mm |
4 inches |
| Factory: |
Rue St. Fargeau, Paris |
France |
| Date of Manufacture: |
Approx 1910-15 |
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| Original / Present Value: |
Unknown |
Unknown |
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| References: |
1) The Story of the Lamp, published by Osram-GEC 1932, p.3. Reference considered to be incorrect. |
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2) Modern Electrical Illumination, by Cyril Sylvester & Thomas Ritchie, publ. Longmans Green & Co., 1927, p.321. Reference considered to be incorrect. |
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3) History of the Electric Lamp, by Fin Stewart, ISBN: 978-0-646-23418-2, 2013, p.176. |
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4) Van Gaslicht tot Gloeilamp, by Antoon Devogelaere, publ. Pelckmans, ISBN 90-289-1272-X, 1987, pp.60-62. |
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5) Private Communication, Ray Tye, London (UK), April 2015. |
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6) Private Communication, Antoon Devogelaere, Gent (BE), April 2015. |
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7) Private Communication, Wieger Nieuwenhout, Leeuwarden (NL), April 2015. |
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8) Advertisement of Société Française AUER for the O.R. Lamp, 1912, on website of French National Library. |
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9) Advertisement of Société Française AUER for the O.R. Lamp, 1912. |
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10) Advertisement of Société Française AUER for the O.R. Lamp, 1912. |
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11) Advertisement of Société Française AUER for the O.R. Lamp, 1912. |
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12) Advertisement of Société Française AUER for the O.R. Lamp, 1912. |
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13) French Patent FR11225, Procédé de Fabrication des Lampes Electriques à Incandescence, Société Française Auer, 17th June 1907. |
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14) French Patent FR8481, Procédé de Fabrication des Lampes Electriques à Incandescence, Société Française Auer, 12th November 1907. |
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15) Austrian Patent AT40573, Träger für Metallglühfäden Elektrischer Glühlampen, Société Française Auer, 26th February 1908. |
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16) Swiss Patent CH43542, Procédé pour la Calcination des Filaments pour Lampes Electriques à Incandescence, Société Française Auer, 11th July 1908. |
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17) French Patent FR10031, Procédé de Fabrication des Lampes Electriques à Incandescence, Société Française Auer, 9th November 1908. |
