It will be observed that the springing of the groined vaulting of the choir (which is now demolished, or, possibly, was never completed) is still visible, rising from the caps of the vaulting shafts (see Fig. 802). The groining, like the other features of the structure, was of a complete character, corresponding to the perfected style of the architecture. It comprised the usual transverse, diagonal, and wall ribs, and had also, as is common in English examples, intermediate ribs, or tiercerons and ridge ribs. These can all be traced in the remaining fragments. But what is more remarkable is that the remains of another and independent tier of vaulting can be observed above the groined roof. This is evident from the Sketch (see Fig. 802), which shows the springing of an upper plain pointed barrel vault, strengthened at intervals with transverse ribs. Grose compares this with the vaulting of King’s College Chapel, Cambridge; but he has mistaken the purpose of the different vaults. That of Cambridge was introduced in order to carry the pendants of the fan-vaulting below, whereas that of Lincluden has evidently been built to support a stone roof above. Plain pointed barrel vaults are very common in Scottish churches, and are invariably introduced for the purpose of supporting a roof of overlapping stone slabs. Numerous examples occur in this work, and roofs of that description were also very usual in the castles--as at Borthwick, &c. Generally, the barrel vault is visible from the interior; but in the present instance, the building being a decorated one, a roof of groined vaulting has been intended under the plain vault. Grose speaks of a third roof of timber over the barrel vault, and both his drawing and Pennant’s indicate a turf or straw covering. But that could hardly be original. The building was, in their time, almost as ruinous as now, and it is very likely that the stone slabs of the roof had been removed, and a temporary wooden roof substituted, or a covering of turf laid over the barrel vault, which, perhaps, at that time still remained. The space between the two vaults would form a chamber, which may have been used as a sleeping apartment. The window in the gable is still visible. A similar apartment, with a window, seems to have existed over the vaulting of the south transept, and both appear to have entered from the turret stair in the wall between the nave and choir. A similar roof to the above occurs at St. Mirren’s Aisle, Paisley Abbey, where the two vaults, with a small chamber between them, still exist.