The entrance to the chancel is 4 feet 3 inches wide, of which 4 feet in height of the jambs remain. They are 3 feet 7 inches thick from west to east, but if the construction was that suggested above, the jambs were 7 feet from west to east, including an entrance into each turret 2 feet wide. (Fig. 109.) The entrance to the chancel was probably surmounted by a semicircular arch of whinstone, plastered, about 8 feet or 9 feet high to the apex, with string-course caps 4 or 5 inches deep. The angles were not chamfered. [Illustration: FIG. 109.--Church on Brough of Birsay. Entrance to Chancel, and Interior Elevation of West End.] There is a step in this entrance of only 2 inches, and from that to the east end of the apse was flush originally. The pavement is of flagstones. This low position of the original altar is peculiar. The chancel is 10 feet 9 inches east and west, and 10 feet 3 inches inside. Only one window remains, which is in the north wall of chancel, and this has lost its lintel (Fig. 110). The clear opening was 3 feet by 10½ inches, with, as stated, a square head. The window has an internal and external splay, each widening to 1 foot 10½ inches. This form is peculiar. There was probably a frame, fixed in the narrow part of the opening, containing glass. In this wall, just east of the window and lower, is a square ambry, 3 feet high by 2 feet 8 inches wide, and 1 foot 11 inches in recess. The use of so large an ambry is not evident. The bottom of it is only 2 feet above the floor. There is no appearance of its having had doors. In the north-east part of the nave of Enhallow Chapel is a similar recess, and one in the same position as this in the chapel on the Brough of Deerness. It is possible, but not probable, that these were Easter sepulchres. In the Kirk of the Ness, North Yell, is a larger one. Of the south wall of the chancel so little remains that nothing can be stated as to window piscina or sedile. It is remarkable that the floor was originally level to the end of the apse, and no elevation given to the altar, which was probably at the chord of the apse; but in later times they built a reredos which _blocked off_ the apse, and then they appear to have made steps to the altar. Some part of the altar remains. It appears to have been 4 feet 1 inch by 2 feet 7 inches. Possibly the reredos did not reach many feet high, so that the upper part of the apse appeared over it. [Illustration: FIG. 110.--Church on Brough of Birsay. Section from West to East.]