Calibration of Lamps
The candlepower of a lamp was measured by judging by eye the relative brightness of adjacent surfaces, one illuminated only by a standard lamp (or candle) and the other only by the lamp under test. The distance of one of the lamps was adjusted until the two were judged to give equal brightness. The candlepower of the lamp under test could then be calculated from the two distances and the inverse square law.
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Famous quotes containing the word lamps:
“And though thou notest from thy safe recess
Old friends burn dim, like lamps in noisome air
Love them for what they are; nor love them less,
Because to thee they are not what they were.”
—Samuel Taylor Coleridge (1772–1834)