The ecclesiastical architecture of Scotland from the earliest Christian times to the seventeenth century; vol. 1/3

by David MacGibbon; Thomas Ross

Fig. 15.—St. Trophime, Arles.

Owing to the occurrence of frequent fires in the wooden roofs of early churches, the builders aimed at carrying out the Roman practice of fireproof vaulting. This was at first done timidly and with many failures. The round barrel vault of the Romans was that generally employed; but in Provence the pointed barrel vault ([Fig. 15]) was adopted from an early period, being a form which exerted on the side walls a less horizontal thrust than the semi-circular arch, and was the best shape for supporting a stone roof laid upon it. In order to strengthen this vault, a projecting ring or inner arch was constructed under the main vault, and extended across the nave between each pair of the main piers.

Carrying out the principle of subordination already introduced, each of these strengthening rings had a shaft with cap and base placed so as to receive it, thus indicating to the eye the principle on which it acted—viz., that of carrying the weight of the strengthening rib down to the foundation.

Fig. 16.—Groined Vault.

By the eleventh century the principle of subordination had been carried out into every part of the structure, and some refinement was beginning to be attempted; shafts were substituted for the plain orders of the piers, and a cap and base provided for each (see [Fig. 14.]), and the sharp angles of the orders of the arch were softened by having large roll mouldings wrought upon them. The next step in the progress of development was the subdividing or groining of the vault, so as to admit of windows for the purpose of lighting the upper part of the building, which, with the barrel vault, was found to be very dark. ([Fig. 16]). Many different plans were tried to improve the lighting of the vault, but without satisfactory result, till recourse was had to the intersecting vault of the Romans, still visible in many structures then surviving. This mode of vaulting consisted in the introduction of a vault crossing the structure between each set of piers at right angles to the main vault, and it had at once the desired effect, as it enabled the side walls containing windows to be carried up as high as the top of the vault, thus giving ample light. Other very important consequences followed from this improvement of the vaulting. Hitherto, with the barrel vault, the pressure had been uniform over the side walls, which were made very solid to resist it; but with the introduction of the groined vaulting, the weight of the vault was concentrated on the points where the groins rested. This necessitated the strengthening of these points, which was managed by means of buttresses. These are simply portions of wall set at right angles to the building in order to receive the weight and thrust of the arches and carry them down to the ground. The portion of the side wall between the buttresses was thus relieved from any pressure beyond its own weight. It is evident that an entire change in the principles of the construction of the edifice would thus be created. The buttresses now became important members both in the construction and the appearance of the building. The side walls, being now mere enclosing screens, might be reduced from their previous massive condition, and made as thin and light as desired, while the windows in them might be enlarged to any extent. The same remarks apply to the side aisles, the vaulting of which was also groined and supported on buttressed points like the main vaults. With the solid materials of the Romans, the groins or lines of meeting of the intersecting arches formed simple curved lines or angles; but with the smaller materials of the mediæval architects this construction could not easily be accomplished, and it became usual to construct the groins with a solid stone rib, at first plain, but in later examples enriched with a roll moulding.

The development of mediæval architecture reached the point above described during the course of the twelfth century. The Romanesque architecture of Lombardy, Germany, and Burgundy had wrought out the arrangement of the groined vaulting and the distribution of the forces arising therefrom, and the designing and construction of the necessary buttresses. The subordination of the various members, the division of the piers and arches into orders, each performing a distinct function, the erection of a vaulting shaft at each pier to receive the ribs of the vaults, the construction of ribs to form the groins and carry the panels of the vaults, had all been fully accomplished. Each shaft was supported on a base and crowned with a cap to receive its load, and each order of the arches received an appropriate moulding or enrichment. Thus far were the constructional features of a genuine arched style of construction, in stone, wrought out during the course of the eleventh and early part of the twelfth centuries.

The forms of the ornament kept pace with the development of the construction. In the earlier centuries the Romanesque style had become stereotyped, the general features being regarded as wrought out, and invention limited itself to the elaboration of details and ornaments. Hence it arose that much of the Romanesque ornament was overloaded and inapplicable to its position. But as advances were made in the direction of improving the vaulting and other constructional elements, the builders’ energies were also directed towards improvement of the decorative features, the heavy unsuitable ornaments were discarded, and lighter and more appropriate forms introduced.

This new phase of architecture was adopted by the Normans with their usual energy, and during the twelfth century was carried out by them, both in Normandy and England, to an advanced state of development, thus constituting the well-known Norman style.