A Treatise on Industrial Photometry with Special Application to Electric Lighting

New York and London: D. Van Nostrand Company and Sampson Low, Marston & Company, Limited 1894. First Edition. ix, [1 blank], 322 pages. Original blue cloth. 8vo. Original brown glossy endpapers offsetting to title page and rear endpapers (browning overall). Front hinge reglued. Corners bumped, minor creasing to boards. Clean internally otherwise, a good reading or reference copy of an early book on the subject. Good. Cloth. [22720]

"Photometry is the science of the measurement of light, in terms of its perceived brightness to the human eye. It is distinct from radiometry, which is the science of measurement of radiant energy (including light) in terms of absolute power. In modern photometry, the radiant power at each wavelength is weighted by a luminosity function that models human brightness sensitivity. Typically, this weighting function is the photopic sensitivity function, although the scotopic function or other functions may also be applied in the same way." (from Wikipedia)

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