Alvan Graham Clark (July 10, 1832 – June 9, 1897), born in Fall River, Massachusetts, was an American astronomer and telescope-maker. He was the son of Alvan Clark, founder of Alvan Clark & Sons.
On January 31, 1862, while testing a new 18½ inch refracting telescope, he made the first observation of Sirius B in Cambridgeport, Massachusetts. The magnitude 8 companion of Sirius is also the first known white dwarf star.
The 18½ inch refracting telescope is still being used at the landmark Dearborn Observatory of Northwestern University in Evanston, Illinois.
http://www.todayinsci.com/