NATIONAL PHYSICAL LABORATORY: SCIENCE AND TECHNOLOGY IN WARTIME, TEDDINGTON, MIDDLESEX, ENGLAND, UK, 1944 - In the Photometry Section of the Light Division at the National Physical Laboratory, tests are carried out to measure the light output and efficiency of various types of lamp. The large sphere to the right of the photograph contains a lamp which is being measured by a photocell or 'electric eye' in combination with electrical measuring apparatus

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