Joseph-Émile Barbier

Background

Barbier was born on March 18, 1839, in Saint-Hilaire-Cottes, Pas-de-Calais, in the north of France.

Education

Barbier studied at the College of Saint-Omer, also in Pas-de-Calais, and then at the Lycée Henri-IV in Paris. He entered the École Normale Supérieure in 1857, and finished his studies there in 1860, the same year in which he published the paper containing his theorem on constant-width curves.

Career

In 1860 Barbier passed his agrégation and taught mathematics at the lycée of Nice, where he does not seem to have been appreciated by his students. Le Verrier, director of the Paris Observatory, was impressed by Barbier’s keen insight and offered him a position as assistant astronomer. Barbier was fully aware of the usefulness to astronomy of mathematics, physics, chemistry, and instrumental techniques, and he was thus a valuable collaborator. During this period he published numerous reports concerned with various problems in astronomy and the most diverse types of mathematics. His ingenuity led him to perfect a new type of thermometer.

Barbier’s work is scattered in thirty or more memoirs and reports, of which about two-thirds were published during his brief career as a professor and assistant astronomer (1860-1866); most of the others were published between 1882 and 1887.

Several of the studies in the first series bear on the mathematical aspects of astronomy (spherical geometry and spherical trigonometry), on the construction of new thermometers, and on other aspects of instrumental techniques. The others deal with infinitesimal calculus and elementary and infinitesimal geometry, as well as with the calculus of probabilities.

The last works of Barbier dealt almost entirely with mathematics and made several interesting contributions to geometry (the theory of polyhedra, the indicatrix of Dupin), integral calculus, and the theory of numbers.

Despite the illness that ruined his career, Barbier deserves to be numbered among the good unspecialized mathematicians of the late nineteenth century.

Achievements

• Barbier`s last works, that dealt almost entirely with mathematics, made several interesting contributions to geometry with the theory of polyhedra, the indicatrix of Dupin, integral calculus, and the theory of numbers. Thus, Barbier deserves to be numbered among the good unspecialized mathematicians of the late nineteenth century.

Personality

While studying at the École Normale Supérieure, Barbier astonished his fellow students by his acute intelligence and his ability to grasp the deeper meanings of complex problems. He also had a taste for subtlety that led him to detect the errors in the most classic demonstrations. A good observer, Barbier showed himself also to be an able calculator.

But later in life Barbier seemed to become more and more unstable and strange. In 1865 he left the observatory, and after attempting to enter a religious order broke off all contacts with his associates. Only in 1880 was he discovered in the asylum at Charenton-St. Maurice, where he had been sequestered for several years. Although Barbier never recovered his sanity, the gentleness of his behavior caused him to be released, and he spent his last years in a more serene environment.

Connections

Friend:

Joseph Bertrand

Joseph Bertrand, permanent secretary of the Académie des Sciences, encouraged him to return to scientific writing and was able to secure for him regular financial help from a foundation connected with the Academy. The numerous reports published thereafter were irreproachably sound and often most original.

References

• Dictionary of scientific biography
  1970