Rigdon, Sidney a prominent Mormon leader, was born in St. Clair, Beaver County, Pennsylvania, February 19, 1793, and received a fair English education. I1 learned the printer's trade, and was working in an office in Pittsburgh when, about 1812, a manuscript was offered for publication by an eccentric preacher named Solomon Spaulding, which was entitled, The Manuscript Found, or, The Book of Mormon. Rigdon was so much interested in the work that he made a copy before it was returned to Spaulding, who died a short time after. About 1817 Rigdon became a Campbellite preacher, with an evident leaning towards Adventism. In 1829 he became acquainted with Joseph Smith, and arranged with him to have the Book of Mormon published, as the basis for a new sect. From this time he was closely identified with the Mormon movement, going with the new body, and suffering persecution with them. He was a candidate for the leadership on the death of Smith, and on the election of Brigham Young refused to acknowledge his authority. Accordingly he was excommunicated, and returned to Pittsburgh. He afterwards lived in obscurity, and died at Friendship, N.Y., July 14, 1876. SEE MORMONS.