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Description: | 644 ROYAL "EDISWAN" POINTOLITE (PATENT) MADE IN ENGLAND 500 C.P. 100V-250V (acid etched on the glass envelope) MANU The Edison Swan Electric Company Limited. circa 1922 Head Office, 155, Charing Cross Road, London, W.C.2.
Works, Ponders End, Middlesex. England DES after MULLARD,Stanley,Robert. 1914 Duck Lees Lane, Ponders End, Enfield, Middlesex, England. This is a fixed focus Pointolite lamp primarily used in microscopy and photography where a steady light source was required. This type of Pointolite lamp produced about 1,240 candles/square inch max. The lamp worked by striking an arc between an ioniser composed of tungsten spiral partially inside a tungsten/thorium oxide tube and a tungsten bead. At first the arc transfers from the tungsten spiral to the tube as it reaches working temperature. In this version the arc is then from the tube to a tungsten plate. The lamp is filled with a nitrogen argon mix and fitted with an Edison triple contact screw cap. The envelope is hand made with an internal cowl to collect and condense tungsten oxides to prevent darkening of the glass and was filled from a pip in the top. The tungsten arc incandescent lamp was described by A.E. Gimingham and S.R. Mullard, Journ., I.E.E., 1st December 1915. N.B. Gimingham was Crookes' assitant and inventor of the Gimingham pump used by Ediswan at Ponders End to pump down Ambrose Fleming's vacuum tubes for his rpatent work on the thermionic valve. | 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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