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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 used from 1884-1888. From 1888-1894 it was superseded by a longer type having more screw threads, whose open end was spun in to a smaller diameter to yield a stronger bond to the bulb.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 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 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 1892. It is sealed to an enlarged olive-section in the stem. The bulb shows the classic rounded tip, common to Edison lamps.
| Manufacturer: | Edison Lamp Company | |
| Lamp Power: | Approx. 72 Watts | |
| Lamp Voltage: | 110 Volts | |
| Lamp Current: | Approx. 0.65 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: | 2.8 lm/W | 4.47 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 120 hours | |
| Burning Position: | Vertical only | (to avoid filament sag) |
| Overall Length: | 140mm | 5¼ inches |
| Light Centre Length: | 82mm | 3¼ inches |
| Factory: | Harrison, NJ | U.S.A |
| Date of Manufacture: | 1884 - 1886 | |
| Original / Present Value: | Unknown | Unknown |
