Complex sentence: He was a delegate to the New York State Constitutional Convention in 1821, and was Chancellor of New York from 1823 to 1826, when he resigned, having been by-elected Senator, and served from January 14,1826, to March 3,1831.
Split into simpler sentences: He was a delegate to the New York State Constitutional Convention in 1821, and was Chancellor of New York from 1823 to 1826. In 1826 he resigned the chancellorship after his by-election to the Senate, and served from January 14,1826, to March 3,1831.