File:Light and lighting (1908) (14783939335).jpg

Identifier: lightlighting07illu (find matches)
Title: Light and lighting
Year: 1908 (1900s)
Authors: Illuminating Engineering Society Association of Public Lighting Engineers (Great Britain)
Subjects: Lighting
Publisher: (London)
Contributing Library: Knox - University of Toronto
Digitizing Sponsor: University of Toronto

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lis referred to an indirect light-ing installation which he had carried outwith Mr. R. A. Smith, in the VauxhallBridge Road. The specification stipu-lated the use of inverted type of arc lampwith semi-luminous reflectors. Aftergoing carefully into the calculations, itwas decided to take an average value of3*5 foot-candles on the working plane,which was taken as 3 ft. 3 in. from thefloor. After two years an average figureof 3-207 foot-candles was obtained byphotometric measurement. The diversity The most interesting part of this pro-position was the necessity for colourmatching ; the buyers stating that it wasimpossible to match colours, particularlyin silky materials, by artificial lighting.In order to deal with this problem, experi-ments were carried out with six differenttypes of arc lamp, and as a result it wasdecided to install indirect arcs with semi-luminous reflectors, as it was found thatthis was the only form of artificial lightingby which colour matching could be carriedout.
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coefficient was 2-3, and he obtained it inexactly the same way as Mr. Clinton hadillustrated in the paper. He showed anumber of slides illustrating this indirectlighting installation. The lamps werehung 2 ft. 6 in. from the ceiling in rooms11 ft. 6 in. high, and 3 ft. from the ceilingin rooms 13 ft. 6 in. high, the lampsbeing fixed at 17 ft. centres in squareformation. (See illustration.) Mr. Justus Eck said that he also hadbeen struck by the remarkably concordantresults obtained from calculations madeand measurements made especially in thecase of some of the installations of incan-descent electric lighting. He was also interested in the referenceto ageing made by Mr. Ritchie. Thisseemed to him a most important point,because if as a result of their calculations 238 THE ILLUMINATING ENGINEER (may) they were going to put forward valueswhich would only hold good at the firsttest when everything was absolutely new,they would be misleading everybody andlosing reputation. It would therefore

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