Alvan Clark

Biography

Clark began his career as a portrait painter and engraver, working in that field from the 1830s into the 1850s. At age 40 he turned to telescope making. His firm, Alvan Clark & Sons, ground lenses for refracting telescopes using glass blanks from Chance Brothers of Birmingham, England, and Feil-Mantois of Paris, France. Among their lenses were the largest in the world at the time: an 18.5-inch lens for Dearborn Observatory at the Old University of Chicago, two 26-inch telescopes for the United States Naval Observatory and McCormick Observatory, a 30-inch for Pulkovo Observatory (destroyed in the Siege of Leningrad, with only the lens surviving), a 36-inch for Lick Observatory, and a 40-inch for Yerkes Observatory, which remains the largest successful refracting telescope. While testing completed objectives, Clark discovered several double stars, including Mu Herculis, 8 Sextantis, and 95 Ceti. His son Alvan Graham Clark discovered the dim companion of Sirius. Two craters bear Clark Sr.'s name: Clark on the Moon is jointly named for him and his son, and one on Mars is named in his honor. His other son, George Bassett Clark, was also a partner in the firm. Clark was competitive in target shooting and received a patent for a device that allowed bullets to be seated into a muzzle-loading rifle without damage. Exclusive license to this patent was made to Edwin Wesson. In 1880, Clark was elected as a member to the American Philosophical Society.