Ernest Benjamin Esclangon (17 March 1876 – 28 January 1954) was a French

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

and

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...

. Born in Mison, Alpes-de-Haute-Provence, in 1895 he started to study mathematics at the

École Normale Supérieure École or Ecole may refer to: * an elementary school in the French educational stages normally followed by Secondary education in France, secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing i ...

, graduating in 1898. Looking for some means of financial support while he completed his doctorate on quasi-periodic functions, he took a post at the Bordeaux Observatory, teaching some mathematics at the

university A university () is an educational institution, institution of tertiary education and research which awards academic degrees in several Discipline (academia), academic disciplines. ''University'' is derived from the Latin phrase , which roughly ...

. During

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

, he worked on

ballistics Ballistics is the field of mechanics concerned with the launching, flight behaviour and impact effects of projectiles, especially weapon munitions such as bullets, unguided bombs, rockets and the like; the science or art of designing and acceler ...

and developed a novel method for precisely locating enemy artillery. When a gun is fired, it initiates a spherical

shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a me ...

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 An armistice is a formal agreement of warring parties to stop fighting. It is not necessarily the end of a war, as it may constitute only a cessation of hostilities while an attempt is made to negotiate a lasting peace. It is derived from t ...

in 1919, Esclangon became director of the Strasbourg Observatory and professor of astronomy at the

the following year. In 1929, he was appointed director of the

Paris Observatory The Paris Observatory (, ), a research institution of the Paris Sciences et Lettres University, is the foremost astronomical observatory of France, and one of the largest astronomical centres in the world. Its historic building is on the Left Ban ...

and of the

International Time Bureau The International Time Bureau (, abbreviated BIH), seated at the Paris Observatory, was the international bureau responsible for combining different measurements of Universal Time. The bureau also played an important role in the research of tim ...

, and elected to the

Bureau des Longitudes __NOTOC__ The ''Bureau des Longitudes'' () is a French scientific institution, founded by decree of 25 June 1795 and charged with the improvement of nautical navigation, standardisation of time-keeping, geodesy and astronomical observation. Durin ...

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 The French Academy of Sciences (, ) is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific method, scientific research. It was at the forefron ...

in 1939. Esclangon was the President of the Société astronomique de France (SAF), the French astronomical society, from 1933–1935.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 World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

and the German occupation of Paris, he retired in 1944. He died in Eyrenville, France. The

binary asteroid A binary asteroid is a system of two asteroids orbiting their common barycenter. The binary nature of 243 Ida was discovered when the Galileo spacecraft flew by the asteroid in 1993. Since then numerous binary asteroids and several triple a ...

1509 Esclangona is named after him. The lunar crater Esclangon is named after him. His doctoral students include Daniel Barbier, Édmée Chandon, Louis Couffignal, André-Louis Danjon, and Nicolas Stoyko.

References

External links

* {{DEFAULTSORT:Esclangon, Ernest 20th-century French astronomers 1876 births 1954 deaths Members of the French Academy of Sciences École Normale Supérieure alumni Academic staff of the University of Strasbourg People from Alpes-de-Haute-Provence 20th-century French mathematicians Presidents of the International Astronomical Union