Twelve appears to be the largest number of panes employed in a sliding sash in Philadelphia architecture, even in public buildings, except a few churches. There are such sashes in Independence Hall, Congress Hall, Carpenters' Hall, the Free Quakers' Meeting House at Fifth and Arch streets and the main building of the Pennsylvania Hospital. In Congress Hall and Carpenters' Hall there are also round-topped windows with twelve-paned lower sashes and upper sashes having ten small ornamental panes to make up the semicircle above twelve rectangular panes. A few similar windows with seven ornamental panes in the round top are to be seen in Christ Church. [Illustration: PLATE LXVIII.--- Parlor, Stenton; Reception Room, Stenton.] [Illustration: PLATE LXIX.--Dining Room, Stenton; Library, Stenton.] The Old Swedes' Church has a few rectangular windows with fifteen-and sixteen-paned upper and lower sashes, while over the front entrance there is a window having a twelve-paned upper and a sixteen-paned lower sash. In Christ Church are to be seen two windows having ten-paned upper and fifteen-paned lower sashes set in a recessed round brick arch. For the most part, however, the church windows of this period were round-topped, the upper sash being higher than the lower. Most of the windows of St. Peter's Protestant Episcopal Church have fifteen-paned lower sashes, the upper sashes consisting of twenty rectangular panes above which twelve keystone-shaped panes and one semicircular pane form the round top. The windows of Christ Church are larger still and particularly interesting because of the heavy central muntin to strengthen the sash. On the first story the lower sashes have twenty-four panes and the upper ones eighteen rectangular panes with sixteen keystone-shaped and two quarter-round panes to form the semicircular top. On the second floor the windows are the same except for the eighteen-paned lower sashes. Each side of the steeple on the lower story is a window of this size, notable for the ornamental spacing of twenty-one sash bar divisions, the sweeping curves of which form spaces for glass reminiscent of the Gothic arch. These windows slide in molded frames set in the reveals of the brickwork under plain arches with marble or other stone imposts, keystone and sill. The imposts and keystone were often molded and otherwise hand-tooled, as on Christ's Church, and the sills were sometimes supported by a console at each end, as on St. Peter's Protestant Episcopal Church. Some of the windows of both of these churches illustrate the frequent employment of slightly projecting brick arches and pilaster casings at the sides.