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Description: | D-250-100W MADE IN ENGLAND 4071 "OSRAM" PATENT G.E.C. (acid etched on the glass envelope). 10 (moulded or stamped on the glass cane). 25010 (written in black on the base of the cane). 52.0X.2. (written in black on the base of the envelope). The D prefix indicates that the lamp was probably intended for a 250 volt direct current lighting system. MANU General Electric Company Limited of England. between 1909 and 1922 Osram Works, Hammersmith, London, England. DES after SWAN,Joseph,Wilson,Sir. 1878 Newcastle-Upon-Tyne England This is a 250 volt 100 Watt general lighting service lamp with a Swan double contact bayonet two pin cap and a clear orb shaped envelope. The single ductile tungsten squirrel cage filament is clinched to the nickel platinum copper composite lead in wires. It is supported by a lower set of nine stout molybdenum wires and an upper set of ten fine wires mounted on a central glass cane. The upper support wires are in the form of fine crooks not loops.The first tungsten filaments were developed circa 1906 using a process similar to the squirted carbon filament but a ductile tungsten process, by which tungsten powder is compressed and then forged into billet before being drawn through a series of diamond dies, was developed in 1909. The envelope is a hand made type with a pintel or pip. The bulb being evacuated from the top of the envelope. | License: | http://www.hmag.gla.ac.uk/spirit/rights/ | Publisher: | Hunterian Museum and Art Gallery, University of Glasgow | Rights holder: | Hunterian Museum and Art Gallery, University of Glasgow | Subjects: | SCIENTIFIC COLLECTION : | Source: | Hunterian Museum | Creator: | Hunterian Museum and Art Gallery, University of Glasgow | Identifier: | http://www.huntsearch.gla.ac.uk/cgi-bin/... | Language: | en-GB | Go to resource |
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