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Edison Bamboo Filament with Copper Clamps |
Prior to 1884 all Edison lamps employed a strain relief ring of plaster of paris between the base and bulb, not present here. The type of base on this lamp was in use between 1884 and 1888. In 1888 and until 1894 it was superseded by a longer type having more screw threads, whose open end was spun in to a smaller diameter to yield a stronger bond to the bulb.
The filament is a carbonised bamboo fibre strip of rectangular cross-section, having enlarged ends. It is of Japanese Madake bamboo. This was in production from 1880 to 1886, after which thinner square-section filaments were adopted.
Another identifier is the method of affixing the filament to the platinum leading-in wires. These have been flattened at their extremities and crimped around the filament, the joint then being fixed by electroplating a layer of copper over the whole. This method of electroplating was used between 1881 and 1886, after which the carbon paste joint was introduced.
The leading-in wires are made of platinum throughout the whole stem, a method that was used until 1890. Thereafter the weld to the external lead-wires was included in the glass stem press to reduce the required length of platinum.
The bulb is of a type free-blown in the air from 1" diameter tubing. Moulded bulbs were not introduced until 1894. It is sealed to an enlarged olive-section in the stem. The bulb shows the classic enlarged tip common to early Edison lamps.
| Manufacturer: | Edison Lamp Company | |
| Lamp Power: | Approx 90 Watts | |
| Lamp Voltage: | 110 Volts | |
| Lamp Current: | 0.8 Amperes | |
| Cap Type: | Edison Screw | Open top 1884-1888 style |
| Bulb Type: | SA-56 | SA-18 in eighths/inch |
| Bulb Finish: | Clear | Soda-lime glass |
| Filament Type: | Bamboo strip, rectangular | Enlarged end sections |
| 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: 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: | Harrison, N.J. | U.S.A. |
| Date of Manufacture: | 1884 - 1886 | |
| Original / Present Value: | Unknown | Unknown |
