Candela frequency and that has a radiant intensity in that direction of watt per steradian. The definition describes how to produce a light source that (by definition) emits one candela, but does not specify the luminosity function for weighting radiation at other frequencies. Such a source could then be used to calibrate instruments designed to measure luminous intensity with reference to a specified luminosity function. An appendix to the SI Brochure makes it clear that the luminosity function is not uniquely specified, but must be selected to fully define the candela. The candela is sometimes still called by the old name
Rosario Candela as well as social cynosure." Born in Montelepre, Sicily in 1890, Candela immigrated to New York in 1906. He returned to Sicily after his arrival to study there and returned to the US in 1909. His father was Michele Candela, a plasterer, and his mother was Josephine Pizzurro. He gained admission to the Columbia University School of Architecture and graduated in 1915. Keenly aware of his talent, he went so far as to erect a velvet rope around his drafting table to prevent other students from copying his designs. After graduation, Candela worked briefly as a draftsman for the Palermo-born