The Rectangulus: A Scientific Astronomical Calculator

Richard of Warrenford was a Benedictine monk at St. Albans in the early 13th century. He went to Oxford for his degree, but returned to the monastery after he finished it. Richard and Warrenford built an astronomical clock that took him eight years to complete. The abbey's walls were crumbling so they had to be repaired by another Abbott who died from leprosy.