| 释义 |
Hefner Physics.|ˈhɛfnə(r)|
The shortened name of F. F. von Hefner-Alteneck (1845–1904), German electrical engineer, used attrib. to designate esp. a lamp devised by him and formerly used as a photometric standard and the intensity of light obtained from it, as Hefner candle (see quot. 1943); Hefner (amyl or amyl-acetate) lamp, a lamp of standard dimensions and with standard parts burning amyl acetate. Also Hefner flame, Hefner kerze (G., = candle), Hefner standard, Hefner unit. Also occas. in full Hefner-Alteneck lamp, etc.
1891Jrnl. Soc. Chem. Industry X. 685/2 A discussion on the subject of amyl acetate, the fuel of the Hefner lamp, has recently taken place. 1896Electrician 2 Oct. 738/2 The standard of light will be either the Vernon-Harcourt or the Hefner-Amyl-Acetate. 1898Electr. Rev. XLII. 795/1 As a result of the investigations of the German Reichsanstalt, the Hefner lamp alone fulfils all technical requirements. The light of the Hefner lamp is designated a Hefner candle. Ibid., The Hefner candle was accepted as the international unit of light by the Electrical Congress at Geneva in 1896. 1901Phil. Trans. R. Soc. A. CXCVI. 26 Knowing the value of the energy of the visible light of the Hefner standard, the heating effect of the rays can be deduced. Ibid. 37 The chief source of difficulty in the comparison is the difference in colour between the light from the Hefner lamp and a fluorescent screen. 1902Encycl. Brit. XXX. 235/2 For accurate scientific purposes the best standard is the Hefner-Alteneck or amyl-acetate lamp. 1911Ibid. XXI. 526/2 Various experimental investigations into the properties of the Hefner flame. 1914S. E. Sheppard Photo-Chem. 23 Viollé's unit was found by Lummer to equal 26 Hefner units. Ibid. 24 The light-unit 1 HK (Hefner-Kerze or Hefner candle) is taken as the mean of protracted observations on a Hefner lamp at the Physik. Techn. Reichsanstalt in Charlottenburg. 1917G. Martin Industr. & Manuf. Chem. II. 357 The Hefner candle power is equal to about 0·9 British standard candle. 1943Gloss. Terms Electr. Engin. (B.S.I.) 112 Hefner candle, a unit of luminous intensity equal to that of the Hefner lamp burning under specified conditions of atmospheric pressure and humidity. It is the official unit of luminous intensity in Germany and is accepted internationally as equivalent to 0·9 candle. 1963Jerrard & McNeill Dict. Sci. Units 30 Germany, however, continued to use the Hefner candle (Hefnerkerze HK) unit which was derived from the Hefner lamp and had a luminous intensity of about 0·9 International candles. |