Bk. II. Ch. I. POINTED ARCHES. 449 vault, as the Romans had done on their domes, and also, so far as we know, on those of their thermæ. Had they used a circular vault for this purpose, it is evident, from the right-hand side of the diagram, that to obtain a straight-lined roof externally, and the necessary water- shed, it would have been requisite to load the centre of the vault to a most dangerous extent, as at a ; whereas with the pointed arch it only required the small amount of filling up shown at b, and even that might have been avoided by a little contrivance if thought necessary. 310. Diagram of Vaulting. S<mtli ot France. By adopting the jiointed form the weiglits are so distributed as to ensure stability and to render the vault self-supporting. It lias already been observed that the Gothic architects everywliere treated their vaults as mere false ceilings, covering them with a i-oof of wood — an expedient higldy objectionable in itself, and the cause of the destruc- tion, by fire or from neglect, of almost all the churches we now find in ruins all over Europe ; Avhereas, had they a<lliered either to the Roman or Romance style of roofing, the constant upholding hand of man would not have been required to protect their Iniildings from decay. 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 shall hereafter see, 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 simi)le 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 VOL. I. — 29
