Bouguer, PIERRE

1698-1758. French physicist, sent with others to S. America 1735, to measure a degree of the meridian at the equator; they remained seven years and made valuable observations on the length of a second's pendulum in high altitude, and on the deviations of the plumb line due to a neighboring mountain, etc., and laid the foundation of photometry. He invented a heliometer, afterward improved by Fraunhofer. Figure of the Earth , 1749; Optics , 1760.