Seaton was born in Norfolk, New York, in 1831 and served as an officer in the Civil War with the First Vermont Sharpshooters. He resigned his commission in 1864 to become an agent in the pension department of the Sanitary Commission, and later, chief clerk of the U.S. Pension Office. Seaton served as a division chief in the 1870 census and was superintendent of the New York state census of 1875. In 1879, he was appointed chief clerk of the tenth census under Francis Amasa Walker. When Walker resigned in 1881 to accept the presidency of the Massachusetts Institute of Technology, Seaton succeeded him as superintendent of the census, serving until the temporary Census Office closed. He died in Vermont in March 1885.

By 1870, the census had become so extensive that it could no longer be processed by inaccurate and expensive hand tabulations. In a bid to solve this problem, Seaton invented a machine to tally census results. It was first used by the office in 1872 for the 1870 census and then again in 1880 before being replaced by Herman Hollerith’s electronic tabulation machine in 1890. Seaton also invented a matrix printing apparatus for census work.