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Description: | 125V 40 W 832 MADE IN ENGLAND DRAWN WIRE DICK KERR & Co LTD BRITTANNIA (acid etched on the glass envelope with the Brittannia trade mark). 0X 251 (written in black on the base of the envelope). 320 F5 (written in black on the base of the cane). DK (stamped or moulded in the base of the cane). 125 (written in black on the end cap). MANU Dick Kerr and Company Limited between 1910 and 1922 England DES after SWAN,Joseph,Wilson,Sir. 1878 Newcastle-Upon-Tyne England This is a 125 volt 40 Watt general lighting service lamp with a non standard Swan double contact bayonet two pin cap compatible with type No B22/25x26 and a clear bell shaped envelope with a pip or pintel. The single ductile tungsten squirrel cage filament is clinched to the nickel lead in wires. The union between the copper and the nickel is made by a short length of platinum in the base of the cane. It is supported by a lower set of six stout molybdenum wires and an upper set of seven mounted on a central glass cane. The support wires are in the form of fine crooks in the top set and heavier loops in the bottom.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 blown vacuum type with a pintel or pip. The bulb being evacuated via the pintel in 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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