[Illustration: FIG. 110.--Church on Brough of Birsay. Section from West to East.]
As there were no buttresses, it is not likely that the chancel was vaulted. The roof was probably of tie-beam construction, or of rafters coupled half-way up, as in cottages, and covered as the nave roof. It is probable that the apse was vaulted, and the arch into it may be conjectured to have been 10 feet high, and semicircular, and to have formed part of a plain vault, as at Orphir and St. Margaret’s Chapel at Edinburgh. The ground plan is somewhat in the form of a horse-shoe internally. Probably there was a small window in east end, and this must have been at a lower level than the one on the north.
The interior of the nave is of the proportion of the vesica piscis. The width of the chancel is less than of the nave by the thickness of the side walls. The interior of the chancel is square. It is stated in Barry[133] to have been dedicated to St. Peter, and to have been a place of pilgrimage. The writer was informed that many years ago a skewer was found, with a skull, outside the chapel. This was probably the pin of a winding sheet.
There can be little hesitation in assigning this church to about 1100. It is recorded that Earl Thorfin built Christ’s Church in Birsay, and that the body of St. Magnus was buried there. It appears probable that if St. Peter’s had been built as long after his death as his canonisation, it would have been dedicated to him. Even if it had been built in memory of St. Magnus before his canonisation, and dedicated to some other saint, probably the dedication would have been changed after his canonisation. As it is recorded that Thorfin built Christ’s Church, it is probable that if he had, St. Peter’s would have been recorded also. It is more probable that it was built by his second son, Erlend, the father of St. Magnus.
This church bears considerable resemblance to Old Bewick, Northumberland, figured in Muir’s “Sketch”; to Moccas and Kilpeck in Herefordshire, and to St. Margaret’s Chapel, Edinburgh.
Mr. Leask of Boardhouse, in 1867, made an excavation in the church, to determine, if possible, whether foundations exist of the walls supposed to have enclosed the west sides of the circular recesses. He found none and found plaster on the north wall of the nave, where the supposed wall should have joined. Possibly the supposed walls were taken down during the time the chapel was used. He found in the north wall of the nave, at 5 feet west of the angle of the recess, an entrance 2 feet 4 inches wide. The position is very unusual. Planned 1866.