Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 239
king pin in the switchhandle is lifted, and the handle turned tothe right until the pointer of the dial onthe left comes to rest at the arrow.A look at the screen will then enable the user to determine easily which of theround spots matches the background. The figure at the selected round spotgives… … A. General view of instrument.
Lighting
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