BOUGUER, PIERRE (1698-1758), French mathematician, succeeded his father, John Bouguer, as regius professor of hydrog raphy at Croisic in lower Brittany. In 1729 he published Essai d'optique sur la gradation de la lumiere, the object of which was to define the quantity of light lost by passing through a given extent of the atmosphere. He found the light of the sun to be 30o times more intense than that of the moon, and thus made some of the earliest measurements in photometry. In 1730 he was made pro fessor of hydrography at Havre, and succeeded P. L. M. de Mau pertuis as associate geometer of the Academie des Sciences. He also invented a heliometer, afterwards perfected by Fraunhofer. In 1735 Bouguer sailed with C. M. de la Condamine for Peru, in order to measure a degree of the meridian near the equator. A full account of this operation was given in 1749 in Figure de la I terre determinee.
The following is a list of his principal works: Traite d'optique sur la gradation de la lumiere (1729 and 176o) ; Entretiens sur la cause d'inclinaison des orbites des planetes (1734) ; Traite de navire, etc. (1746) ; La Figure de la terre determinee, etc. (1749) ; Nouveau traite de navigation, contenant la theorie et la pratique du pilotage ; Solution des principaux problemes sur la manoeuvre des vaisseaux (1757); Operations faites pour la verification du degre du meridien entre Paris et Amiens, par Mess. Bouguer, Camus, Cassini et Pingre See J. E. Montucla, Histoire des mathematiques (1802).