The original 1816 Constitution of Indiana provided for the election of a governor and a lieutenant governor every three years, limited to six years out of any nine-year period. The second and current constitution of 1851 lengthened terms to four years and set the commencement of the governor's term on the second Monday in the January following the election. Governors were allowed to serve for four years in any eight-year period, but a 1972 amendment permitted governors to serve for eight years in any twelve-year period. Should the office of governor become vacant, the lieutenant governor becomes governor. If the office of lieutenant governor is vacant, the president "pro tempore" of the Indiana Senate becomes governor; this has happened once, when James B. Ray succeeded William Hendricks.