Simon Newcomb (1835-1903) was an astronomer and mathematician remembered for his work in recalculating the major astronomical constants to a new international standard. He was a founding member of the American Astronomical Society and became its first president in 1899. Although Newcomb's mathematical work is well known, this autobiography, first published in 1903, focuses on his achievements and work as an astronomer. In it he provides an account of his scientific research with comments on his approach, which together with his descriptions of scientific discoveries and collaborations occurring in Washington DC show the variety of scientific research being conducted in the United States in the late nineteenth century. His detailed descriptions of how telescopes were used, together with accounts of his experience of working conditions in various observatories, provide valuable insights into astronomical research methods in the late nineteenth century.