lumenn.

Brit.

/ˈl(j)uːmᵻn/,

/ˈl(j)uːmɛn/, U.S.

/ˈlumən/

Forms: Plural lumina /ˈl(j)uːmɪnə/.

Etymology: Latin = light; an opening.

1. An opening, passage, or canal.

a. Anatomy and Zoology.

ΚΠ

1873 T. H. Green Introd. Pathol. & Morbid Anat. (ed. 2) 81 The vessel thus calcified, loses its..contractility; its lumen is diminished.

1888 Beddard in Encycl. Brit. XXIV. 680/2 A longitudinal fold on the dorsal side which projects into the lumen of the intestine.

1893 A. E. Shipley Zool. Invertebr. 214 In the lumen of the siphon is a small valve.

b. Botany.

ΚΠ

1887 H. E. F. Garnsey & I. B. Balfour tr. H. A. de Bary Compar. Morphol. & Biol. Fungi 321 The hyphæ..usually have their walls thickened till the lumina disappear.

1900 B. D. Jackson Gloss. Bot. Terms Lumen, the space which is bounded by the walls of an organ, as the central cavity of a cell.

c. Surgery. The passage of any tube in an instrument.

ΚΠ

1889 Lancet 9 Nov. 949/1 Tracheotomy was resorted to, the larger lumen of the tube affording a freer vent.

1894 Lancet 3 Nov. 1033 The lumen of the catheter.

2. [First adopted, in French, by A. Blondel 1894, in La Lumière électrique 7 July 10.] A unit of luminous flux (now incorporated into the International System of Units), equal to the flux emitted by a point source of intensity one candela (formerly, one candle) into a solid angle of one steradian. The total flux emitted by a source of one candela is 4π (= about 12·57) lumens.

ΘΚΠ

the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > unit of light intensity

lux1889

lumen1898

L1915

Lambert1915

phot1917

new candle1938

candela1950

cd1950

rayleigh1956

the world > matter > light > illumination > [noun] > unit of illumination > candela > units depending on

lumen1898

footlambert1915

1898 Astrophysical Jrnl. 7 300 Luminous current is defined as the rate at which luminous energy is emitted by a point-source through a solid angle of one steradian. Unit: The luminous current of one candle, i.e., of one Hefner lamp. Name: ‘Lumen’. Proposed by L. Weber.

1916 Standard. Rules Amer. Inst. Electr. Engineers § 857 Lumen, the unit of luminous flux, equal to the flux emitted in a unit solid angle (steradian) by a point source of one candle-power.

1926 Encycl. Brit. II. 409/2 In the United States the standard is the lumen or the amount of light that would fall on a surface [?add one square foot in area] so placed that all its parts are at a distance of one foot from a light source of one candle power.

1937 Times 13 Apr. p. iv/2 Electric discharge lighting..has been recently installed to give an even and intense illumination of 1,120,000 lumens so that any flaw or defect in the panels being produced may be detected at once.

1953 S. W. Amos & D. C. Birkinshaw Television Engin. I. vii. 125 The efficiency of electric lamps is usually expressed in lumens per watt... For gas-filled lamps the efficiency increases steadily with the rating and is approximately 10 lumens per watt for 25 W lamps, 13 lumens per watt for 100 W lamps and 17·5 lumens per watt for 1 kW lamps. Thus a 100 W lamp radiates a total of 1,300 lumens and is equivalent to a source of 1,300/4π, i.e., approximately 100 candle-power.

1974 Which? Mar. 88/3 The long-life bulbs gave a light output of about 600 lumens after one hour of life.

Compounds

lumen-hour n. the quantity of light corresponding to a flux of one lumen radiated for one hour.

ΘΚΠ

the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > unit of light intensity > specific measurements

candle-metre1908

lumen-hour1925

lumen-second1930

1925 Trans. Illuminating Engin. Soc. (U.S.) 20 630 The Lumen-hour is the unit of quantity of light. It is equal to a flux of one lumen continued for one hour.

1975 Times 21 Mar. 20/3 The public wanted a certain package of candlepower (expressed in lumens); the industry assured certain fixed wattages, and then aimed at the minimum cost per lumen-hour for those wattages.

lumen-second n. see lumen-hour n.

ΘΚΠ

the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > unit of light intensity > specific measurements

candle-metre1908

lumen-hour1925

lumen-second1930

1930 tr. L. P. Clerc's Photogr. ii. 7/2 The unit of exposure is the lumen-second or candle-metre-second.

1958 Newnes Compl. Amateur Photogr. x. 110 The light output of a flash~bulb is measured in lumen seconds.

This entry has not yet been fully updated (first published 1903; most recently modified version published online June 2018).

单词	lumen
释义	lumenn. Brit. /ˈl(j)uːmᵻn/, /ˈl(j)uːmɛn/, U.S. /ˈlumən/ Forms: Plural lumina /ˈl(j)uːmɪnə/. Etymology: Latin = light; an opening. 1. An opening, passage, or canal. a. Anatomy and Zoology. ΚΠ 1873 T. H. Green Introd. Pathol. & Morbid Anat. (ed. 2) 81 The vessel thus calcified, loses its..contractility; its lumen is diminished. 1888 Beddard in Encycl. Brit. XXIV. 680/2 A longitudinal fold on the dorsal side which projects into the lumen of the intestine. 1893 A. E. Shipley Zool. Invertebr. 214 In the lumen of the siphon is a small valve. b. Botany. ΚΠ 1887 H. E. F. Garnsey & I. B. Balfour tr. H. A. de Bary Compar. Morphol. & Biol. Fungi 321 The hyphæ..usually have their walls thickened till the lumina disappear. 1900 B. D. Jackson Gloss. Bot. Terms Lumen, the space which is bounded by the walls of an organ, as the central cavity of a cell. c. Surgery. The passage of any tube in an instrument. ΚΠ 1889 Lancet 9 Nov. 949/1 Tracheotomy was resorted to, the larger lumen of the tube affording a freer vent. 1894 Lancet 3 Nov. 1033 The lumen of the catheter. 2. [First adopted, in French, by A. Blondel 1894, in La Lumière électrique 7 July 10.] A unit of luminous flux (now incorporated into the International System of Units), equal to the flux emitted by a point source of intensity one candela (formerly, one candle) into a solid angle of one steradian. The total flux emitted by a source of one candela is 4π (= about 12·57) lumens. ΘΚΠ the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > unit of light intensity lux1889 lumen1898 L1915 Lambert1915 phot1917 new candle1938 candela1950 cd1950 rayleigh1956 the world > matter > light > illumination > [noun] > unit of illumination > candela > units depending on lumen1898 footlambert1915 1898 Astrophysical Jrnl. 7 300 Luminous current is defined as the rate at which luminous energy is emitted by a point-source through a solid angle of one steradian. Unit: The luminous current of one candle, i.e., of one Hefner lamp. Name: ‘Lumen’. Proposed by L. Weber. 1916 Standard. Rules Amer. Inst. Electr. Engineers § 857 Lumen, the unit of luminous flux, equal to the flux emitted in a unit solid angle (steradian) by a point source of one candle-power. 1926 Encycl. Brit. II. 409/2 In the United States the standard is the lumen or the amount of light that would fall on a surface [?add one square foot in area] so placed that all its parts are at a distance of one foot from a light source of one candle power. 1937 Times 13 Apr. p. iv/2 Electric discharge lighting..has been recently installed to give an even and intense illumination of 1,120,000 lumens so that any flaw or defect in the panels being produced may be detected at once. 1953 S. W. Amos & D. C. Birkinshaw Television Engin. I. vii. 125 The efficiency of electric lamps is usually expressed in lumens per watt... For gas-filled lamps the efficiency increases steadily with the rating and is approximately 10 lumens per watt for 25 W lamps, 13 lumens per watt for 100 W lamps and 17·5 lumens per watt for 1 kW lamps. Thus a 100 W lamp radiates a total of 1,300 lumens and is equivalent to a source of 1,300/4π, i.e., approximately 100 candle-power. 1974 Which? Mar. 88/3 The long-life bulbs gave a light output of about 600 lumens after one hour of life. Compounds lumen-hour n. the quantity of light corresponding to a flux of one lumen radiated for one hour. ΘΚΠ the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > unit of light intensity > specific measurements candle-metre1908 lumen-hour1925 lumen-second1930 1925 Trans. Illuminating Engin. Soc. (U.S.) 20 630 The Lumen-hour is the unit of quantity of light. It is equal to a flux of one lumen continued for one hour. 1975 Times 21 Mar. 20/3 The public wanted a certain package of candlepower (expressed in lumens); the industry assured certain fixed wattages, and then aimed at the minimum cost per lumen-hour for those wattages. lumen-second n. see lumen-hour n. ΘΚΠ the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > unit of light intensity > specific measurements candle-metre1908 lumen-hour1925 lumen-second1930 1930 tr. L. P. Clerc's Photogr. ii. 7/2 The unit of exposure is the lumen-second or candle-metre-second. 1958 Newnes Compl. Amateur Photogr. x. 110 The light output of a flash~bulb is measured in lumen seconds. This entry has not yet been fully updated (first published 1903; most recently modified version published online June 2018). < n.1873
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