Hefner lamp

The lamp was invented by Friedrich von Hefner-Alteneck in 1884 and he proposed its use as a standard flame for photometric purposes with a luminous intensity unit of the Hefnerkerze (HK).

[1] The Hefner lamp provided the German, Austrian, and Scandinavian standard for luminosity during the late nineteenth and early twentieth centuries.

The unit of light intensity was defined as that produced by the lamp burning amyl acetate with a 40 mm flame height.

The light unit was adopted by the German gas industry in 1890 and known as the Hefnereinheit.

In 1897 it was also adopted by the Association of German Electrical Engineers under the name Hefnerkerze (HK).