Hefner-Alteneck, Friedrich Franz von

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Hefner-Alteneck, Friedrich Franz von

(b. Aschaffenburg, Germany, 27 April 1845; d. Berlin, Germany, 7 January 1904)


Hefner-Alteneck was the son of art historian Jakob Heinrich von Hefner-Alteneck and Elise Pauli. After completing his education at the technical high school of Zurich, a departure from the literary-artistic traditions of his family, Hefner-Alteneck spent most of his professional life (1867–1890) as a design engineer and inventor in the employ of Siemens and Halske, electrical apparatus manufacturers in Berlin. The profitability of his inventions was rewarded by his meteoric rise in the company’s technical staff and, through profit sharing, exceptional remuneration. The technical merit of his work earned him an international professional reputation. Hefner-Alteneck was a member of the Elektrotechnische Verein (president 1893–1894 and 1897–1898, honorary fellow 1900), a fellow of the Royal Swedish Academy of Sciences (1896), and a fellow of the Prussian Academy of Sciences (1901). He received an honorary Ph.D. from the University of Munich in 1897.

His first great success (1872) was the drum armature principle for dynamos, which is still in use. By placing the active conductors entirely on the peripheral surface of the rotating armature, he greatly increased the efficiency and output relative to existing designs using the Gramme-Pacinotti ring armature or the Siemens double-T armature.

Hefner-Alteneck’s other inventions of major importance were a mechanical dynamometer to measure power transmitted by a drive belt, based on tension differential between the two sides of the belt (1872); a teletypewriter with alphanumeric keys to generate Morse code signals for telegraph transmission (1873); a two-current differential regulator for arc lamps which facilitated series and parallel connection of the lamps and led immediately to extensive street-lighting installations (1878); and an amyl acetate lamp as a unit of luminous intensity which, under the name “Hefner candle,” was standard in Germany for more than forty years (1884). Other inventions included electric telemetering of remote water-level data; an electric servomechanism for ships’ telegraphs; an automatic fire-alarm signaling system; and a method for railway block signaling. His work on the important rotating-field generator principle was done with Karl Hoffmann.

Although Hefner-Alteneck’s inventions created no new fields of technology, they enormously accelerated the early growth of the electrical industry. Many of them were improvements on prior conceptions of his employer, Werner Siemens, but they were so revolutionary that Siemens himself was always first to assign credit to his design engineer.

When Siemens gave control of the company to his sons in 1890, Hefner-Alteneck rebelled at being their subordinate and requested a partnership. This was refused, and he retired on full pension at age fortyfive. He continued to be active in professional societies, and from 1898 to 1904 he served on the advisory board of AEG, the German General Electric Company. His friendship with the Siemens family survived their differences, and it was while holidaying at the home of Werner’s son Wilhelm that he died suddenly of a cerebral hemorrhage in 1904.


Apart from patent records, the principal source of public information about Hefner-Alteneck’s work is in twenty-five reports in the Elektrotechnische Zeitschrift (ETZ) between 1880 and 1902, concerning his presentations to the Elektrotechnische Verein. In many cases these reports were made several years after the effective dates of the inventions. Representative papers in ETZ include “Ueber eine neue dynamoelektrische Maschine für kontinuirlichen Strom,” 2 (1881), 163–170; “Ueberelektrische Beleuchtungs-Versuche in den Strassen Berlins,” 3 (1882), 443–450; “Vorschlag zur Beschaffung einer konstanten Lichteinheit,” 5 (1884), 20–24; “Ueber Arbeitsmesser,” 8 (1887), 514–517; and “Vorschläge zur Aenderung unseres Patentgesetzes,” 21 (1900), 278–279.

The only substantial biography is Friedrich Heintzenberg, Friedrich von Hefner-Alteneck (Munich, 1951).

Robert A. Chipman

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