High Quality Content by WIKIPEDIA articles! Alvan Clark (March 8, 1804 – August 19, 1887), born in Ashfield, Massachusetts, the descendant of a Cape Cod whaling family of English ancestry, was an American astronomer and telescope maker. He was a portrait painter and engraver (ca.1830s-1850s), and at the age of 40 become involved in telescope making. Using glass blanks made by Chance Brothers of Birmingham and Feil-Mantois of Paris, his firm Alvan Clark & Sons ground lenses for refracting telescopes, including the largest in the world at the time: the 18.5-inch (470 mm) at Dearborn Observatory at the Old University of Chicago (the lens was originally intended for Ole Miss), the two 26-inch (660 mm) telescopes at the United States Naval Observatory and McCormick Observatory, the 30-inch (760 mm) at Pulkovo Observatory (destroyed in the Siege of Leningrad; only the lens survives), the 36-inch (910 mm) telescope at Lick Observatory (still third-largest) and later the 40-inch (1,000 mm) at Yerkes Observatory, which remains the largest successful refracting telescope in the world.

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