The justice and federal government: In relation to Powhatan legislation Spelman wrote that he "believed that Infidels don lawless yet when I observed sum set to loss of life." He wrote that murderers and thieves had been punished. He devised a system of measuring the circumference and diameter of the earth, which was afterwards put into practice by the khalif al-Ma'mun in 829 and repeated a couple a long time later.