Alvan Graham ClarkBorn 10 Jul 1832; died 9 Jun 1897 at age 64.American astronomer, who joined his father and brother in the family firm of Alvan Clark & Sons, world-famous makers of exceptional lenses for refracting telescopes, supplied to various observatories in the U.S. and Europe. His fascination with astronomy, which began in school, continued through his life. In 1861, while viewing Sirius during a test of a new lens, he observed the faint twin star beside it, Sirius B, which had been predicted almost two decades earlier by Friedrich Bessel in 1844. He discovered fourteen double stars in all. He went on total-eclipse expeditions to Jerez, Spain (1870) and Wyoming (1878). Carrying on the family business, after the deaths of his father and brother, Clark made the 40" diam. lenses of the Yerkes telescope (the world's largest refractor). He died shortly after their first use.«[Image: Clark beside the crown-glass element of the Yerkes Observatory 40-inch objective.] |
