Friedrich Heinrich Philipp Franz von Hefner-Alteneck (April 27, 1845 in
Aschaffenburg
Aschaffenburg (; South Franconian German, South Franconian: ''Aschebersch'') is a town in northwest Bavaria, Germany. The town of Aschaffenburg is not part of the Aschaffenburg (district), district of Aschaffenburg, but is its administrative sea ...
– January 6, 1904 in
Biesdorf near Berlin) was a German
electrical engineer and one of the closest aides of
Werner von Siemens
Ernst Werner Siemens (von Siemens from 1888; ; ; 13 December 1816 – 6 December 1892) was a German electrical engineer, inventor and industrialist. Siemens's name has been adopted as the SI unit of electrical conductance, the siemens. He foun ...
. He is largely remembered for the invention of the
Hefner lamp
The Hefner lamp, or in German ''Hefnerkerze'', is a flame lamp used in photometry that burns amyl acetate.
The lamp was invented by Friedrich von Hefner-Alteneck in 1884 and he proposed its use as a standard flame for photometric purposes with ...
, which provided the measure of
luminous intensity
In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human e ...
used in Germany, Austria and Scandinavia from 1890 to 1942. The measure was called the ''Hefnerkerze'' (HK). The Hefnerkerze was superseded in the 1940s by the modern
SI unit, the
candela
The candela ( or ; symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous t ...
.
He was elected a member of the
Royal Swedish Academy of Sciences in 1896.
Notable Inventions
von Hefner-Alteneck's most notable inventions were all conceptualized during his time at Siemens.
* Differential arc lamp - A type of automatic-feed carbon
arc lamp
* Drum armature - An efficient form of winding motor rotor coils
* A telegraph keyboard
* The
Hefner lamp
The Hefner lamp, or in German ''Hefnerkerze'', is a flame lamp used in photometry that burns amyl acetate.
The lamp was invented by Friedrich von Hefner-Alteneck in 1884 and he proposed its use as a standard flame for photometric purposes with ...
Gallery
File:Hefnerlampe.png, Hefner lamp
The Hefner lamp, or in German ''Hefnerkerze'', is a flame lamp used in photometry that burns amyl acetate.
The lamp was invented by Friedrich von Hefner-Alteneck in 1884 and he proposed its use as a standard flame for photometric purposes with ...
inveted by Hefner-Alteneck
References
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External links
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1845 births
1904 deaths
Engineers from Bavaria
Members of the Royal Swedish Academy of Sciences
German electrical engineers
People from Aschaffenburg
{{Germany-engineer-stub