{{short description|German instrument maker (1803–1877)}} {{Infobox person | image = Ruhmkorff.png | birth_name = Heinrich Daniel Rühmkorff | birth_date = {{birth date|1803|1|15|df=yes}} | birth_place = [[Hanover]], [[Electorate of Hanover]], [[Holy Roman Empire]] | death_date = {{death date and age|1877|12|20|1803|1|15|df=yes}} | death_place = [[Paris]], [[French Third Republic]] | resting_place = [[Montparnasse Cemetery]], Paris | known_for = [[Ruhmkorff coil]]<br>[[Commutator (electric)#Ruhmkorff commutator|Ruhmkorff commutator]] | awards = [[Volta Prize]] (1858) }} [[Image:Ruhmkorff coil.png|250px|right|thumb|Ruhmkorff inductor]] [[Image:Ruhmkorff grab.jpg|250px|right|thumb|Tombstone of Heinrich Daniel Ruhmkorff on the [[Montparnasse Cemetery]] in Paris]]
'''Heinrich Daniel Rühmkorff''' ({{IPA|de|ˈhaɪnʁɪç ˈdaːni̯ɛl ˈʁyːm.kɔʁf|lang}}; [[anglicized]] as '''Ruhmkorff'''; 15 January 1803 – 20 December 1877) was a German instrument maker who commercialised the [[induction coil]] (often referred to as the Ruhmkorff coil).
Ruhmkorff was born in [[Hanover]]. He changed the "ü" to "u" in his name when living abroad. After an apprenticeship with a German mechanic, he moved to England. Contemporaneous and extant biographies have made the assertion that he worked with the inventor [[Joseph Bramah]], but this is unlikely since Bramah died in 1814. He may, though, have worked for the Bramah company. In 1855, he set up a shop in Paris, where he gained a reputation for the high quality of his electrical apparatus.
Although Ruhmkorff is often credited with the invention of the [[induction coil]], it was in fact invented by [[Nicholas Callan]] in 1836. Ruhmkorff's first coil, which he patented in 1851, utilized long windings of copper wire to achieve a spark of approximately 2 inches (50 mm) in length. In 1857, after examining a greatly improved version made by an American inventor, [[Edward Samuel Ritchie]],<ref>American Academy of Arts and Sciences, ''Proceedings of the American Academy of Arts and Sciences'', Vol. XXIII, May 1895 - May 1896, Boston: University Press, John Wilson and Son (1896), pp. 359-360: Ritchie's most powerful version of his induction coil, using staged windings, achieved electrical ''bolts'' two feet (61 cm) or longer in length</ref><ref>Page, Charles G., ''History of Induction: The American Claim to the Induction Coil and Its Electrostatic Developments'', Washington, D.C.: Intelligencer Printing House (1867), [https://books.google.com/books?id=lrzn9ZX79jAC&pg=PA104 pp. 104-106]</ref> Ruhmkorff improved his design (as did other engineers), using glass insulation and other innovations to allow the production of sparks more than 30 centimetres long.<ref>American Academy, pp. 359-360.</ref> Ruhmkorff patented the first version of his induction coil in 1851, and its success was such that in 1858 he becomes the first recipient of the [[Volta Prize]], 50,000 French franc award by [[Napoleon III]] for one of the most important discoveries in the application of electricity. He died in Paris in 1877.
The [[Gas-discharge lamp#The "Ruhmkorff" lamp|Ruhmkorff lamp]]s or 'Ruhmkorff's apparatus' mentioned in several of [[Jules Verne]]'s science-fiction novels<ref>''Journey to the Center of the Earth'' (1864), ''From the Earth to the Moon'' (1865), and ''20,000 Leagues Under the Sea'' (1869).</ref> relied on induction coils but were not developed by Ruhmkorff.
==Asteroid== The [[asteroid]] [[15273 Ruhmkorff]], discovered in 1991 by [[E. W. Elst]], is named after Heinrich Daniel Ruhmkorff.
==References== {{Reflist}}
==Further reading== *H.S. Norrie, [https://books.google.com/books?id=hxBLAAAAMAAJ&pg=PR1 ''Ruhmkorff Induction-Coils, Their Construction, Operation and Application''.] (New York, New York: Spon & Chamberlain, 1896).
==External links== {{Commons category|Heinrich Daniel Ruhmkorff}} *[https://web.archive.org/web/20060525034116/http://chem.ch.huji.ac.il/~eugeniik/history/ruhmkorff.htm Biography] with photographs accessed April 12, 2006 *{{cite Americana|wstitle=Ruhmkorff, Heinrich Daniel|year=1920|short=x}} *[http://www.sparkmuseum.com/INDUCT.HTM Spark Museum—Induction coils]
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{{DEFAULTSORT:Ruhmkorff, Heinrich Daniel}} [[Category:1803 births]] [[Category:1877 deaths]] [[Category:19th-century German inventors]] [[Category:Burials at Montparnasse Cemetery]] [[Category:Scientists from Hanover]] [[Category:Emigrants from the Kingdom of Hanover]] [[Category:German emigrants to the United Kingdom]] [[Category:German emigrants to France]]