​PRATT, ORSON (1811-1881), Mormon apostle, was born of humble parents at Hartford, New York. In 1830 he joined the Mormon Church, becoming a member of its council of twelve in 1834 and one of its twelve apostles in 1835. Pratt was also a mathematician of some note. He was professor of mathematics in the university of Deseret and wrote several books on this subject, these including Cubic and Biquadratic Equations (1866). He was a member, and several times speaker, of the Utah House of Representatives. Among his writings may be mentioned Key to the Universe (1866) and The Bible and Polygamy (1870).