Though he had little conventional schooling, he made important contributions to timekeeping as well as other fields in applied mathematics such as economics and statistics in addition to writing a science fiction novel.
Simon Newcomb was born in the town of Wallace, Nova Scotia. His parents were Emily Prince, the daughter of a New Brunswick magistrate, and itinerant school teacher John Burton Newcomb. John moved around teaching in different parts of Canada, particularly in different villages in Nova Scotia and Prince Edward Island. Emily was a daughter of Thomas Prince and Miriam Steeves, making Simon a great-great-grandson of Heinrich Stief, and a not-too-distant cousin of William Henry Steeves, a Canadian Father of Confederation.
Newcomb seems to have had little conventional schooling other than from his father and from a short apprenticeship to Dr. Foshay, a charlatan herbalist, in New Brunswick in 1851. Nevertheless, his father provided him with an excellent foundation for his future studies. Newcomb's apprenticeship with Dr. Foshay occurred when he was only 16. They entered an agreement that Newcomb would serve a five-year apprenticeship during which time Foshay would train him in using herbs to treat illnesses. For two years he was an apprentice but became increasingly unhappy and disillusioned with his apprenticeship and about Foshay's unscientific approach, realizing that the man was a charlatan. He made the decision to walk out on Foshay and break their agreement. He walked the 120 miles (190 km) to the port of Calais in Maine where he met the captain of a ship who agreed to take him to Salem, Massachusetts so that he could join his father. In about 1854, he joined his father in Salem (John Newcomb had moved earlier to the United States), and the two journeyed together to Maryland.
After arriving in Maryland, Newcomb taught for two years from 1854 to 1856; for the first year in a country school in Massey's Cross Roads, Kent County, MD, then for a year at a school not far south in Sudlersville in Queen Anne's County, MD. In his spare time he studied a variety of subjects such as political economy and religion, but his deepest studies were made in mathematics and astronomy. In particular he read Newton's Principia at this time. In 1856 he took up a position as a private tutor close to Washington and he often travelled to that city to study mathematics in the libraries there. He was able to borrow a copy of Bowditch's translation of Laplace's Traité de mécanique céleste from the library of the Smithsonian Institution but found the mathematics beyond him.
Newcomb studied mathematics and physics privately and supported himself by teaching before becoming a human computer (a functionary in charge of calculations) at the Nautical Almanac Office in Cambridge, Massachusetts in 1857. At around the same time, he enrolled at the Lawrence Scientific School of Harvard University, graduating BSc in 1858.