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THE SCHOOL

BIOT Jean-Baptiste

Mathematician, physicist, astronomer

Birth : 1774[Paris]
Death : 1862[Paris]
Promotion IPC : 1795

 

Following his studies at Louis-le-Grand College in 1792, Biot joined up as a gunner in the Northern Army and took part in the Battle of Hondschoote.Admitted as an engineering student to the Ecole des Ponts et Chaussées in January 1794, it is said that Perronet examined him on his deathbed.He left the school in November 1795 to join the very first class of the Ecole Centrale des Travaux Publics (future Ecole Polytechnique) and came to the notice of Monge, who recognised his brilliance.It was this same professor who would save Biot after the events of 13 Vendémiaire Year IV.

Appointed professor of physics at Ecole centrale de Beauvais in 1797, admissions examiner at Polytechnique in 1799, in 1800 he obtained the chair of mathematical physics at the Collège de France.It was at this time that he met Laplace, whom he assisted in correcting the proofs of the latter’s book Celestial Mechanics.

Portrait of BIOT © ENPC
Portrait of BIOT © ENPC

Biography

 

His work, on mathematics and astronomy, physics and chemistry, brought him entry to the French Academy of Sciences in 1803. He identified the extraterrestrial origin of meteorites and in the same year published his Essay on the General History of the Sciences During the French Revolution.With Gay-Lussac, in 1804 he carried out a balloon ascent to observe changes in the Earth’s magnetic field with altitude, ascending to a height of 3400 m.At this time, after a series of measurements on metals, he established a theory of heat conduction.Appointed an associate member of the Bureau des Longitudes in 1806, he travelled to Spain with Arago to conduct geodetic operations for the purpose of extending the measurement of the meridian from France to the Balearic Islands.He conducted similar verifications in Scotland and the Shetland Islands in 1817, Italy and Sicily in 1825, finally concluding in 1827, in an essay on the shape of the earth, that the action of gravity is not the same at all points on a single parallel.

Amongst this scientist’s numerous researches, his work on the polarisation of light had significant consequences.In 1807, Biot came up with the idea of applying the laws of the light polarisation to research on the crystallisation of bodies.He used this method to distinguish between vegetable saps and, in particular, to measure the proportions of crystallisable sugar remaining in molasses.His 1815 apparatus, the saccharimeter, would be used in medicine to diagnose diabetes.From 1809, Biot held the chair in astronomy at the Paris Faculty of Sciences. He coveted the title of secretary for life of the Academy of Sciences, but was unsuccessful in his two applications.However, his literary work, including his Tribute to Montaigne, brought him election to the French Academy in 1856.