 In 1640 , Francis Mansell ( appointed principal in 1630 ) began construction of a second quadrangle with buildings along the north and south sides ; further work was interrupted by the English Civil War . Work began again in 1676 , and the library ( now the Fellows ' Library ) was completed by 1679 . Under Jonathan Edwards ( principal from 1688 to 1712 ) , further rooms were built to complete the quadrangle ; the project was completed just after his death in 1712 . Pevsner described the second quadrangle as " a uniform composition " , noting the " regular fenestration by windows with round @-@ arched lights , their hood @-@ moulds forming a continuous frieze " . The Dutch gables have ogee sides and semi @-@ circular pediments . The writer Simon Jenkins said that the quadrangle has " the familiar Oxford Tudor windows and decorative Dutch gables , crowding the skyline like Welsh dragons ' teeth and lightened by exuberant flower boxes " . 
