The walls of the main nave are wider than the tower. The south aisle (see Fig. 166) is divided into three bays, and the north aisle into two bays. The piers are octagonal, with corresponding responds. There are no capitals on the piers, and the bases have simple splays; the splayed arches of the arcade die against the piers (Fig. 167). From the floor to the springing of the arches is 6 feet 7½ inches, and to the soffit of the arch at the apex is 17 feet 4½ inches. The chancel arch, which is 13 feet 11 inches wide, is treated in a similar manner to the other arches, and is a few feet higher. The roof of the church is shown on the sketch by Nattes as being in one span; so that there does not appear to have been a clerestory over the nave arcade. Now only the foundation of the north aisle wall remains, and the chancel walls are reduced to a few feet in height; while at the west end they have almost disappeared, showing how badly used the place has been during this century. The entrance to the church was by a square-lintelled doorway in the centre of the south wall of the nave, and there appears to have been a priests’ doorway in the south side of the [Illustration: FIG. 166.--Muthill Church. View from South-East.] chancel. There is a door through the east wall of the north aisle, which possibly led into what may have been a sacristy or vestry. At the west [Illustration: FIG. 167.--Muthill Church. West Window and Respond.] end of the north aisle there seems to have been a chapel, lighted with a west window. The windows of the church, of which three remain entire in the south [Illustration: FIG. 168.--Muthill Church. Plan of Windows in South Aisle.] aisle (Fig. 168), contain three lights in each. They are of good design, and resemble windows in the north side of Dunblane Cathedral. The east window in the south aisle of the nave is completely demolished, and only one jamb remains of the west window of the north-west chapel. Over each of the end windows of the south aisle there are small pointed windows, widely splayed towards the [Illustration: FIG. 169.--Muthill Church. Remains of Sedilia.]