Born in Nova Scotia, at the age of 19 Newcomb left an apprenticeship to join his father in Massachusetts, where the latter was teaching.

His father was an itinerant school teacher, and frequently moved in order to teach in different parts of Canada, particularly in Nova Scotia and Prince Edward Island.

Through his mother, Simon Newcomb was a distant cousin of William Henry Steeves, a Canadian Father of Confederation.

Their agreement was that Newcomb would serve a five-year apprenticeship, during which time Foshay would train him in using herbs to treat illnesses.

He borrowed a copy of Nathaniel Bowditch's translation of Pierre-Simon Laplace's Traité de mécanique céleste from the library of the Smithsonian Institution, but found the mathematics beyond him.

For a time he 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.

[5] In particular, Daniel Coit Gilman, president of Johns Hopkins University, was said to have been on the point of awarding tenure to C. S. Peirce, before Newcomb intervened behind the scenes to dissuade him.

[7] Newcomb's motivation has been speculated to have been that, despite he being "no doubt quite bright", "like Salieri in Peter Shaffer’s Amadeus he also had just enough talent to recognize he was not a genius and just enough pettiness to resent someone who was".

In 1861, Newcomb took advantage of a vacancy and was hired as professor of mathematics and astronomer at the United States Naval Observatory, in Washington D.C. Newcomb set to work on the measurement of the position of the planets as an aid to navigation, becoming increasingly interested in theories of planetary motion.

[3] By the time Newcomb visited Paris, France, in 1870, he was aware that the table of lunar positions calculated by Peter Andreas Hansen was in error.

[3] In 1875 he was offered the post of director of the Harvard College Observatory but he declined, having by now settled that his interests lay in mathematics rather than observation.

[3] In 1877 he became director of the Nautical Almanac Office where, ably assisted by George William Hill, he embarked on a program of recalculation of all the major astronomical constants.

From 1884 he also fulfilled a demanding role as professor of mathematics and astronomy at Johns Hopkins University in Baltimore, continuing, however, to reside at Washington.

He was buried with military honors in Arlington National Cemetery with President William Howard Taft in attendance.

He had already started developing a refinement of the method of Léon Foucault when he received a letter from Albert Abraham Michelson, a young naval officer and physicist who was also planning such a measurement.

In 1880, Michelson assisted at Newcomb's initial measurement with instruments located at Fort Myer and the United States Naval Observatory, then situated near the Potomac River.

Michelson had left to start his own project by the time Newcomb arranged a second set of measurements between the observatory and the Washington Monument.

Newcomb used the variation of latitude observations to estimate the elasticity of Earth, finding it to be slightly more rigid than steel.

In an article in Science, he wrote: "What lies before us is an illimitable field, the existence of which was scarcely suspected ten years ago, the exploration of which may well absorb the activities of our physical laboratories, and of the great mass of our astronomical observers and investigators for as many generations as were required to bring electrical science to its present state.

He ends with the remark "the construction of an aerial vehicle ... which could carry even a single man from place-to-place at pleasure requires the discovery of some new metal or some new force.

"[20] In the October 22, 1903, issue of The Independent, Newcomb made the well-known remark that "May not our mechanicians ... be ultimately forced to admit that aerial flight is one of the great class of problems with which man can never cope, and give up all attempts to grapple with it?

Newcomb was particularly critical of the work of Samuel Pierpont Langley, who claimed that he could build a flying machine powered by a steam engine, but whose initial efforts at flight were public failures.

But when we inquire whether aerial flight is possible in the present state of our knowledge; whether, with such materials as we possess, a combination of steel, cloth and wire can be made which, moved by the power of electricity or steam, shall form a successful flying machine, the outlook may be altogether different.

"[24]Newcomb was not aware of the Wright Brothers' efforts, whose work was done in relative obscurity (Santos-Dumont flew his 14-bis in Paris only in 1906) and apparently unaware of the internal combustion engine's better power-to-weight ratio.