Pierre Bouguer

Pierre Bouguer , born the February 16th 1698 with the Croisic and deceased the August 15th 1758 with Paris, is a Mathématicien, hydrographic Physicien and French.

His/her father, Jean, one of the best hydrographs of his time, were professor with the Croisic and author of a treaty of Navigation. In 1713, Pierre Bouguer is engaged to succeed his/her father. In 1727, it obtains a price of the Academy of Science for its presentation On the best manner of forming and of distributing the masts of the boats and two other prices for its essays On the best method to at sea observe the altitude of stars and On the best method to observe the variation of the compass at sea , taking account of certain anomalies of the Pesanteur.

In 1729, it publishes Test of optics on gradation of light , whose object is to define the quantity of light lost by the passage through an extent given of the terrestrial atmosphere stating for the first time what is often called the Loi of Beer-Lambert and sometimes, more correctly, the Loi of Bouguer. He finds that the light of the Sun is 300 times more intense than that of the the Moon. This test is truly innovator. On the one hand, it is the first report of photometric measurements of Luminance but moreover, Bouguer shows there the phenomenon of adaptation to the luminosity by giving a relative value (of 1/64) to the lower part of which the discrimination of two different luminous intensities is impossible. This last result anticipates two centuries work of the Psychophysique so that one of the founders of this discipline, Ernst Weber will keep its name to indicate the relationship between threshold of detection and intensity: it is the Rapport of Bouguer-Weber also called differential Seuil relative.

In 1730, it is named professor of Hydrographie to the Havre, and succeeds Pierre Louis Maupertuis as geometrician associated with the Academy of Science. He is also the inventor of a Héliomètre, improved then by Joseph von Fraunhofer. He is elected with the Academy of Science in the place of Maupertuis and is established with Paris.

In 1735, it sails with Charles Marie of Condamine, Louis Godin, chief of forwarding, and Joseph de Jussieu for the Peru, in order to measure a degree of the Méridien close to the equator. Ten years are passed for this delicate operation whose report is published in 1749 in Détermination of the Figure of the Earth . At the time of this voyage, it makes observations of a gravimetric nature in altitude and it thus highlights the anomaly which bears its name. In 1746, it makes publish its masterly work Traité ship , the first synthesis of the naval architecture, where it explains the use of the metacenter like measures stability of the ships. Almost all its later writings relate to the theory of navigation and the naval architecture. Bouguer became member of the Royal Society the January 25th 1750.

In Mathematical, Pierre Bouguer works on the Courbe S in the plan and studies, the first, the “ curve of continuation” in 1732. It introduces in 1734 the symbols $\ ge$ for higher or equal and $\ le$ for lower or equal .

Publications

Talks on the cause of the inclination of the orbits of the planets, where one answers the question suggested by the royal Academy of sciences (1724)
Of the mast of the vessels, part which gained the price of the royal Academy of sciences suggested for the year 1727 (1727)
Essai of optics over the gradation of the light (1729)
Traité ship, of its construction and its mouvemens (1746)
Nouveau Treaty of navigation, containing the theory and the practice of piloting (1753)
the Figure of the ground, determined by the observations of Sirs Bouguer and Condamine, sent by order of Roy to Peru to observe around the equator, with a shortened Relation of this voyage which contains the description of the country in which operations were made, by Mr. Bouguer (1749)
Of the Operation of the vessels, or Treated the méchanique one and of dynamics in which one reduces to very simple solutions the most difficult problems of navy, which have as an aim the movement of the ship (1757)
Traité of optics on the gradation of the light, works posthumous of Mr. Bouguer (1760)

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