American Swan Carbon Filament Lamp
Following the establishment of the Swan Lamp Company in Britain, the inventor of that lamp was swift to establish his manufacturing operations around the world. The American factory was established at Boston in 1882, but by 1885 had been sold to Charles Brush, who was eager to get into the new business of incandescent lamps to complement his existing strengths in carbon arc. The company continued to be known as The Swan Lamp Manufacturing Company, but it was in fact a subsidiary of the Brush empire, and in 1885 the incandescent production was transferred to Cleveland, Ohio, where the company rented space from Brush.

This lamp appears to be of a model produced around 1885-1893 at the Brush works. Lamps produced by the company during those years are quite distinctive because of the so-called goal-post design of stem that supports the filament. The origin of this stem design is not known, and it differs considerably from British-made Swan lamps. The platinum wires are first sheathed in glass, then fused to a short length of glass rod that holds them at the desired spacing. It was superseded after the 1893 invention of the flared stem.

The filament is made by Swan's squirted cellulose process and has been attached to the lead wires with carbon deposited by heating the joint while immersed in a liquid hydrocarbon. The cap is of the distinctive British style, made from a short length of 7/8" diameter brass tubing and bearing side pins which retain it in the holder by a bayonet action. As is typical of American Swan lamps, the insulation material is wood and the electrical contacts are simple screws fixed into the wood, the leadwires from the lamp being soldered into the screw heads.
Manufacturer: Swan Lamp Mfg. Co. Division of Brush
Lamp Power: Approx 90 Watts
Lamp Voltage: 100 Volts
Lamp Current: 0.8 Amperes
Cap Type: Bayonet 7/8" (22mm) Wooden Insulator
Bulb Type: P-60 P-19 in eighths/inch
Bulb Finish: Clear Soda-lime glass
Filament Type: Squirted Cellulose Deposited joint
Atmosphere: Vacuum No getter
Luminous Flux: 201 lm 16 Candle Power
Luminous Efficacy: 2.2 lm/W 5.6 Watts per Candle
Beam Intensity: N/A
Beam Distribution: N/A
Colour Temperature & CRI: CCT: Approx. 2000K CRI: Ra 100
Chromaticity Co-ordinates: CCx: 0.527 CCy: 0.413
Rated Lifetime: Approx 800 hours
Burning Position: Vertical only (to avoid filament sag)
Overall Length: 140mm 5¼ inches
Light Centre Length: 82mm 3¼ inches
Factory: Euclid, Ohio U.S.A.
Date of Manufacture: c. 1885-1893
Original / Present Value: Unknown Unknown
 
References: 1) The History of the Incandescent Lamp, John Howell & Henry Schroeder, The Macqua Company, New York, 1927, pp.165-166.
2) Incandescent Lampmakers in Cleveland 1884-1905, Early Incandescent Lamps website, E.J. Covington (Web Archive).
3) Location of the Swan Lamp Manufacturing Company, Early Incandescent Lamps website, E.J. Covington (Web Archive).
4) An Enquiry for Lamp Historians, Early Incandescent Lamps website, E.J. Covington (Web Archive).
5) History of the Adams-Bagnall Electric Company, The Incandescent Electric Lamp 1880-1925, E.J. Covington, NELA Press, 1998 p.10.
6) History of the Fort Wayne Electric Light Company, The Incandescent Electric Lamp 1880-1925, E.J. Covington, NELA Press, 1998 pp.10-15.
7) History of the Fort Wayne Lamp Company, The Incandescent Electric Lamp 1880-1925, E.J. Covington, NELA Press, 1998 pp.15.
8) Cleveland-Based Lamp Manufacturers, The Incandescent Electric Lamp 1880-1925, E.J. Covington, NELA Press, 1998 pp.15.
9) Brush-Swan Lamp of 1887, Past Technology Collection, 2000.
10) Brush-Swan Lamp of 1890s, Spark Museum Collection.
11) Charles F. Brush, Biography by Jeffrey LaFavre.
12) The Brush Electric Company, by Jeffrey LaFavre.