Carbon Filament with Coloured Glass Bulb

During the 1890s The Edison-Swan United Electric Lamp Company excelled in the manufacture of so-called Fancy lamps, and offered a range of several dozen different types each having some feature of decorative value. In addition to these was a broad selection of 'standard' types blown in natural coloured glass.

Whereas today the various lamp manufacturers have rationalised their ranges and offer just five or six plain colours, it is astonishing to glance at the Ediswan catalogues of the 1890s and appreciate the rich variety of colours that were offered. All versions employ natural coloured glass because it would be another two decades before coating materials were developed that could withstand the high operating temperature of the carbon filament lamp without fading or burning off. A staggering fourteen different glass colours were offered plus a further selection of coloured opal versions, and as if that was not enough to satisfy the Victorian consumer, a footnote indicates that the company would be happy to entertain requests for additional hues not listed. This lamp bears a paper label numbered 740, which identifies its colour as Azure Blue. It is thought to have originated from a salesman's set of demonstration lamps.

The rest of the construction of this lamp is similar to ordinary types of its era, having platinum lead wires pinched directly into the neck of the bulb. The filament is secured with a deposited joint of carbon. The bayonet cap is made from standard pipefitters' 7/8" (22mm) brass tubing with plaster of paris insulator. Different glass colours commanded different prices depending on their composition, this model costing just 1 shilling above the price of the clear version.
Manufacturer: The Edison-Swan United Electric Light Co. Ltd.
Lamp Power: Approx 60 Watts
Lamp Voltage: 100 Volts
Lamp Current: 0.6 Amperes
Cap Type: B22d Brass + Plaster of Paris
Bulb Type: P-57t P-18t in eighths/inch
Bulb Finish: Clear Azure Soda-lime glass
Filament Type: Squirted Carbon
Atmosphere: Vacuum
Luminous Flux:
Luminous Efficacy:
Beam Intensity: N/A
Beam Distribution: N/A
Colour Temperature & CRI: CCT: CRI:
Chromaticity Co-ordinates: CCx: CCy:
Rated Lifetime: Approx. 800h
Burning Position: Universal
Overall Length: 100 mm 4 inches
Light Centre Length:
Factory: Ponders End, London Great Britain
Date of Manufacture: c.1890
Original / Present Value: 4s9d (1893) £21.66 (2011)
 
 
References: 1) Catalogue of the Edison & Swan United Electric Lamp Co. Ltd., 1893
2) Catalogue of the Edison & Swan United Electric Lamp Co. Ltd., 1896
3) Catalogue of Exhibits of the Ediswan Collection of Historic Lamps, c. 1930