Thus a monochromatic image of the sun is built up on the fixed photographic plate.
They all squeezed into the front seat—the back seat was piled high with photographic equipment and camping gear.
He was distinguished as the discoverer of radioactivity, having found in 1896 that uranium at ordinary temperatures emits an invisible radiation which in many respects resembles Rntgen rays, and can affect a photographic plate after passing through thin plates of metal.
Photographic telescope was afterwards added, no fewer than 75,000 photographs had been obtained up to the beginning of 1901.
From 1847 to 1862 he was advising astronomer to the headquarters of the army and navy; chairman of the International Astronomical Congress from 1867-1878; acting president of the International Metric Commission in 1872; and president of the International Congress for a Photographic Survey of the Stars in 1887, in which year he was also made a privy councillor.