[Illustration: 544. Diagram of Vaulting. South of France.] The one obstacle in the way of the general adoption of this mode of roofing was the difficulty of applying it to intersecting vaults. The Romans, it is true, had conquered the difficulty; so had the Byzantine architects, as we have already seen, displaying the ends of the vaults as ornaments; and even at St. Mark’s, Venice, this system is adopted, and with the additional advantage of the pointed arch might have been carried further. Still it must be confessed that it was not easy—that it required more skill in construction and a better class of masonry than was then available to do this efficiently and well. The consequence is, that all the Romance pointed vaults are simple tunnel-vaults without intersections, and that the Gothic architects, when they adopted the form, slurred over the difficulty by hiding the upper sides of their vaults beneath a temporary wooden roof, which protected them from the injuries of the weather. This certainly was one of the greatest mistakes they made: had they carefully profiled and ornamented the exterior of the stone roofs in the same manner as they ornamented the inside, their buildings would have been not only much more beautiful, but much more permanent, and the style would have been saved from the principal falsity that now deforms it. Even as it is, if we wished intelligently to adapt the Gothic to our purposes, instead of merely copying it, this is one of the points to which we ought first to turn our attention. [Illustration: 545. Fig. 1. Fig. 2. Fig. 3.] Another circumstance which may be alluded to here, when speaking on this subject, which led to the adoption of the pointed arch at an early age in the southern provinces of France, was the use of domes as a roofing expedient. These, it is true, are not found in Provence, but they are common in Aquitaine and Anjou—some of them certainly of the 11th century; and there can be little doubt but that these are not the earliest, though their predecessors have perished or have not yet been brought to light.