Samuel Alfred Mitchell (April 29, 1874 – February 22, 1960) was a Canadian-American astronomer who studied solar eclipses and set up a program to use photographic techniques to determine the distance to stars at McCormick Observatory, where he served as the director. Early years Mitchell was born in Kingston, Ontario, the son of John Cook and Sarah Chown Mitchell, the sixth of ten children to grow up in the Mitchell home. Mitchell's father (a tenth child) emigrated to Canada from St. Austell, Cornwall. His mother, born in Kingston, was the tenth child of parents who emigrated to Canada from Devonshire. At age twelve Mitchell went off to Kingston Collegiate Institute. From there, he went on to Queen's University where he received his Masters of Arts in mathematics in 1894. While at Queen's University, he acquired knowledge of the techniques of an astronomical observatory when he was asked to care for the astronomical instruments of the university. Upon encouragement from his math professor, Nathan Dupuis, he left in 1895 for Johns Hopkins University to study math under Simon Newcomb, only to find Newcomb retired. Thomas Craig was the new head of mathematics and Mitchell also began study under Charles Lane Poor, the head of astronomy. Poor was an excellent teacher and Mitchell was inclined to follow astronomy from that point on. Mitchell was awarded an astronomy assistantship for his second year at JHU and continued until he received his PhD in 1898 with his thesis published in the Astrophysical Journal, which included a discussion of the amount of astigmatism of a concave grating. While at Hopkins, his astronomy duties consisted of caring for the astronomical transit instrument and the clocks in the little observatory behind the physics laboratory, and the 9.5-inch refractor in the dome of the laboratory roof. Yerkes Observatory Following receipt of his doctoral degree, Mitchell set out for the brand new Yerkes Observatory in Wisconsin where he began work as a research student in 1898. Though he enjoyed his work at Yerkes, he was enticed to move away and became an instructor in astronomy at Columbia University in June 1899. Over the fourteen years he was at Columbia, Mitchell taught undergraduate courses in descriptive astronomy both at Columbia and later for girls from Barnard College, a year long course in geodesy for third year students, which continued into a first semester fourth year course, and a six-week summer