Hefner Candle

Hefner candle [′hef·nər ¦kand·əl]

(optics)

A luminous intensity standard, formerly used in Germany, equal to 0.9 international candle; produced by a Hefner lamp burning under standard conditions. Abbreviated HK. Also known as Hefnerkerze.

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Hefner Candle 

an obsolete unit of luminous intensity. The Hefner candle was adopted as the basic unit for photometric measurements in 1893 in Germany and subsequently in Austria, Switzerland, and the Scandinavian countries. The unit was proposed by the German scientist F. von Hefner-Alteneck in 1884. It is produced by a specially designed wick lamp, which burns amyl acetate, when the flame height is 40 mm is still air at standard atmospheric pressure.

In 1896, the International Electrical Congress adopted the bougie décimale, or decimal candle, which is equal to 1.12 Hefner candles. In 1909, the bougie décimale was replaced by the international candle, which is equal to 1.11 Hefner candles and is produced by means of incandescent lamps (seeCANDLE). However, the Hefner candle was used in Germany until 1948.

REFERENCE

Tikhodeev, P. M. Svetovye izmereniia v svetotekhnike: Fotometriia. Leningrad-Moscow, 1936. Pages 95–96 and 101–02.

K. P. SHIROKOV