Editing Ernest Esclangon

{{short description|French astronomer and mathematician}}
{{Use dmy dates|date=June 2020}}
[[File:Esclangon.jpg|thumb|{{center|Ernest Esclangon, 
by [[Paul Helbronner]], 1930.}}]] 
'''Ernest Benjamin Esclangon''' (17 March 1876 – 28 January 1954) was a French [[astronomer]] and [[mathematician]].

Born in [[Mison]], Alpes-de-Haute-Provence, in 1895 he started to study mathematics at the [[École Normale Supérieure]], graduating in 1898. Looking for some means of financial support while he completed his doctorate on [[quasi-periodic function]]s, he took a post at the [[Bordeaux Observatory]], teaching some mathematics at the [[University of Bordeaux|university]].

During [[World War I]], he worked on [[ballistics]] and developed a novel method for precisely locating enemy artillery. When a gun is fired, it initiates a spherical [[shock wave]] but the projectile also generates a conical wave. By using the sound of distant guns to compare the two waves, Escaglon was able to make accurate predictions of gun locations.

After the [[armistice]] in 1919,<ref>{{cite book |title=The Biographical Encyclopedia of Astronomers |last=Hockey |first=Thomas |year=2009 |publisher=[[Springer Publishing]] |isbn=978-0-387-31022-0 |accessdate=22 August 2012 |url=http://www.springerreference.com/docs/html/chapterdbid/58426.html}}</ref> Esclangon became director of the [[Strasbourg Observatory]] and professor of astronomy at the [[University of Strasbourg|university]] the following year. In 1929, he was appointed director of the [[Paris Observatory]] and of the [[International Time Bureau]], and elected to the [[Bureau des Longitudes]] in 1932. He is perhaps best remembered for initiating in 1933 the first ''[[speaking clock]]'' service, reportedly to relieve the observatory staff from the numerous telephone calls requesting the exact time. He was elected to the [[Académie des Sciences]] in 1939.

Esclangon was the President of the [[Société astronomique de France|Société astronomique de France (SAF)]], the French astronomical society, from 1933–1935.<ref name=BSAF1937>[http://gallica.bnf.fr/ark:/12148/bpt6k96721072/f536.item''Bulletin de la Société astronomique de France'', November 1937, plates X–IX]</ref> In 1935, he received the [[Prix Jules Janssen]], the society's highest award.

Serving as director of the Paris Observatory throughout [[World War II]] and the [[France during World War II|German occupation of Paris]], he retired in 1944. He died in [[Eyrenville]], France.

The [[binary asteroid]] [[1509 Esclangona]] is named after him.

The lunar crater [[Esclangon (crater)|Esclangon]] is named after him.

His doctoral students include [[Daniel Barbier]], [[Édmée Chandon]], [[Louis Couffignal]], [[André-Louis Danjon]], and [[Nicolas Stoyko]].<ref>{{MathGenealogy|id=287385|name=Ernest Esclangon}}</ref>

==References==
{{reflist}}

==External links==
*{{MacTutor Biography|id=Esclangon}}

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[[Category:20th-century French astronomers]]
[[Category:1876 births]]
[[Category:1954 deaths]]
[[Category:Members of the French Academy of Sciences]]
[[Category:École Normale Supérieure alumni]]
[[Category:Academic staff of the University of Strasbourg]]
[[Category:People from Alpes-de-Haute-Provence]]
[[Category:20th-century French mathematicians]]
[[Category:Presidents of the International Astronomical Union]]