In most of the collegiate churches the barrel vaults supported a roof composed of carefully wrought flag-stones. These stones are arranged in courses, running from the eaves to the ridge, and every alternate course is higher than, and rests on, the edges of the intermediate courses. Each stone also overlaps the course which is below it in the slope of the roof. There is thus a considerable amount of cutting and fitting required, which is usually carefully executed. Sometimes each stone is hollowed in the centre, so as to carry the water away from the joints. The gutters are also wrought in stone on the same principle. Roofs of this description might evidently be made almost level, and in the case of many of the castles (as on the keep of Craigmillar Castle) that is done, and a platform for defence is thus created. In the churches, however, the stone roofs are usually pretty steep.
It is remarkable that this form of roof was a reproduction in Scotland, in the fifteenth century, of a fireproof form of construction which was much used in Provence in the eleventh and twelfth centuries. But in this country it was to all appearance an independent invention, as Provence in the fifteenth century was, architecturally speaking, very remote, and was cut off from Scotland by the intermediate styles of England and France.
It should be noted that the pointed barrel vault, although very general, was not universally employed in Scotland during the third period. One or two notable examples of well constructed groined vaults are to be found, such as the vaulting of Trinity College Church and that of “Blackader’s Aisle” in Glasgow Cathedral. But these are exceptions to the general rule.
In Rosslyn College we have the finest example of the late Scottish forms of vaulting carried out to their fullest extent, together with some exceptional designs. This church differs from most of the other collegiate churches in having side aisles, and also in having groined vaults in the east end. The plan of the latter portion of the building, being copied from the arrangement at the east end of Glasgow Cathedral, has been carried out with groining, in imitation of the original; but in the other parts of the structure the vaulting conforms to that of the third pointed period in Scotland. The main central roof is covered with a continuous pointed barrel vault without a break, except an ornamental rib over each division of the bays. The soffits of each panel of the arch thus formed are carved with stars, fleur-de-lys, and other enrichments. The side aisles are also covered with a series of pointed barrel vaults. Each of these aisle vaults forms an extension of the main pier arch of the choir, carried across the aisle at right angles to the main choir. The Scottish plan of avoiding groins is thus adhered to. The above arrangement of the aisle vaults also enables the aisle windows to be carried up to a good height. The barrel vaults across the aisles rest on flat arches (made to resemble straight lintels), which run between the caps of the main piers and the responds against the walls. The whole construction recalls that of a castle with a large central hall roofed with a barrel vault, and having a series of side chambers entering off it, each covered with its separate barrel vault running at right angles to the main building. If the partitions between these side chambers were removed, and plain arches or lintels substituted, the construction would be exactly that of Rosslyn Church. Such a series of chambers, with barrel vaults running at right angles to a passage, is of common occurrence in the ground floors of the Scottish castles. An exceptional feature connected with the main vault of Rosslyn Church is that the same stones which form the interior arch also form the outside roof—the usual overlapping stone covering being omitted, possibly to avoid the extra weight. The exterior of the roof is thus curved like the interior.
During the late pointed period many varieties of details were indulged in. The buttresses are generally somewhat stunted. They are plain and solid, and have often rather elaborate canopies and corbels for statues placed on the front of the buttresses, without recessed niches. The buttresses have frequently numerous set-offs, and are generally finished with stunted square pinnacles having crocketed finials. The windows are almost always pointed, and contain simple tracery derived from the earlier styles. The copying of the forms of the older styles is specially noticeable in the windows and traceries.
At Ladykirk, the unusual form of elliptical windows is introduced, probably in order to admit as much light as possible at the haunches. As above explained, there are generally no aisles, and the windows, being kept down below the springing of the main arch, are, as usual, low, and here leave on the exterior a high space of blank wall above them.
The above form of construction does not require or admit of a triforium and clerestory. At Rosslyn, where there are side aisles, the side walls of the choir are carried up so as to permit of clerestory windows. The tracery is almost always set in the centre of the wall, and the same mouldings, usually double chamfers, are repeated in the reveal both on the inside and outside.
Where the choir, nave, and transepts have square ends, there is generally a large traceried window carried up in the gable under the barrel vault of the roof, by which the principal light in the church is obtained.
The details of the late pointed churches in Scotland have comparatively little connection with the late work either in England or France, but some signs exist of importations from both these countries.
At Melrose Abbey, Linlithgow Church and Palace, and a few other places, there are distinct indications of the influence of the perpendicular style of England; while the French influence is traceable in the apsidal terminations of the choir and occasionally of the transepts, and in some approaches to Flamboyant tracery. The latter influence may probably have also led to the crown-like terminations of some of the church towers. On the whole, however, it will be found that the details of the Scottish late pointed period are peculiar to itself, and are principally founded on survivals and revivals of details of the earlier styles.