CLAUDET, ANTOINE FRANgOIS JEAN (1797 1867), French photographer, was born at Lyons on Aug. 12, 1797. Having acquired a share in L. J. M. Daguerre's invention, he was one of the first to practise daguerreotype portraiture in England, and he improved the sensitizing process by using chlorine in addition to iodine, thus gaining greater rapidity of action. In 1848 he produced the photographometer, an instrument designed to measure the intensity of photogenic rays; and in 1849 he brought out the focimeter, for securing a perfect focus in photo graphic portraiture. He was elected F.R.S. in and in 1858 he produced the stereomonoscope, in reply to a challenge from Sir David Brewster. He died in London on Dec. 27, 1867.