Vault (architecture)

“ This form of vault was of very frequent use, though{187} the exact method of filling in the spaces was not rigidly adhered to. Its disadvantages are, that it either limits the height of the walls available for windows, or runs up so high into the roof as to interfere with its construction. It is in many cases, however, a very convenient, as it is a very sightly, form of vaulting.
Even the simple form of vaulting with level ridges is not always convenient for windows, particularly in clerestories, where they have often to fill the whole space. ”

“ Through a small opening in the outer shell, near its crown, the hand may be thrust into the void, but nothing can be reached. It is a curious form of double vault, and differs fundamentally from the great double dome of the cathedral. The scheme as a whole is structurally inconsistent; for while the inner vault has the concentrated thrusts of Gothic construction, these thrusts are met by the enclosing drum, and not by the isolated abutments that the vault logically calls for. ”

“ No style of architecture has ever evolved nobler forms of ceiling than the groined vault and the dome. Moreover, the use of vaulting made possible effects of unencumbered spaciousness and amplitude which could never be compassed by any combination of piers and columns. It also assured to the Roman monuments a duration and a freedom from danger of destruction by fire impossible with any wooden-roofed architecture, however noble its form or careful its execution. ”

“ The most normal and readily invented vault is that of the continuous barrel or demi-cylindrical form, covering an oblong building from end to end, and the{52} most readily conceived idea, where the building has to be roofed over such a vault, is to fill in the space between the arch and the triangle of the roof solid, and make it at once the ceiling of the room and the support of the roof covering. ”

“ There is a longitudinal rib, and a cross rib along the ridge of the{110} cross vaults, and frequently also an intermediate rib on the surface of the vault. The bosses are rare at first, more abundant afterwards: they are generally well worked and enriched with foliage.
Early English vaults are sometimes of wood only, as in York Minster, and at Warmington, Northamptonshire, and the cloisters at Lincoln. A vault is, in fact, a ceiling, having always an outer roof over it ”

“ Not more than three feet thick, they rise up to a height of nearly seventy feet to support a great stone vault. Four only of the six stand clear from floor to roof, for the two western are embedded at the bottom in the jambs of the gallery arches. From their capitals the vaulting ribs spread out in every direction, being constructively not unlike an English fan vault, and covering the whole roof with a network of lines. The piers are round, stand on round moulded pedestals, and are divided into narrow strips by eight small shafts. ”

“ The centering is then removed, and the vault, being in one piece, stands without abutment or thrust, apparently a better and more durable form of roof than our most scientific Gothic vaulting; certainly far cheaper and far more easily made, since it is literally cast on a mud form, which may be moulded into any shape the fancy of the architect may dictate. ”

“ But the vault supports, unlike those of Senlis and Noyon, consist, as in Paris, of three shafts both in the main and in the intermediate piers—the longitudinal ribs not being independently provided for below the springing of the vaults, but rising from shafts carried by the same capitals which support the diagonal ribs.
Sexpartite vaults occur again in the Cathedral of Laon, a building nearly contemporaneous with the nave of Paris, and here we meet with still another arrangement of supports (Fig. 25) . ”

“ The line of intersection is necessarily weak, and the vault requires aid to make it perfect in construction; and this can only be given it in the form of increased thickness, which is at once obtained by altering the form of the pier from a square to a cross form, and applying to the vault the same principle of divided orders as we have done before to arches (Fig. 236) ; only that, in this case the upper order is a vault, and the lower one only an arched rib coming in to aid the{80} vault. The groined vault is thus divided into compartments, and beauty and strength at once provided for. ”

“ Gothic vaults are never simple intersecting pointed vaults. The new constructive principles did not admit of such forms. Gothic vault-forms do not admit of description in geometric terms. They vary according to the spans, the altitudes, the curves, and the points of springing of the arches that compose the rib system, and it is by the forms and relations of these arches only that such vaults can be described. In the vaults of Paris the filling-in consists of successive courses of arched masonry reaching from rib to rib over each triangular space of the plan. ”

“ They are beyond doubt among the earliest, if they be not the very earliest, sexpartite vaults that were anywhere built. But they are not Gothic vaults, notwithstanding their transverse and diagonal ribs, because the rib system is neither complete nor independent. It is not complete because there are no longitudinal or wall ribs; and it is not independent, though it is not incorporated with the shell of the vault, because the forms of the arches do not determine the forms of the vaults, but are themselves determined by these forms. ”

“ The vault is hardly to be called a real dome, having a series of ribs on its under side, nor does the external covering follow the same curve as the internal, but with admirable judgment it is raised so much as to have rather the effect of a very low spire, with a considerable entasis, than of a regular dome. The exterior angles have lines of simple and boldly contrived crockets, and the stones with which it is covered seem all to have been cut with scallops on their lower edge. The stonework of the exterior is much decayed, but otherwise the whole work stands well and firmly. ”

“ While these perplexities, however, were under consideration, several others arose, every one of which led to the introduction of features essential to the perfecting both of the style and construction. The first was the desire to elevate the central vault to a higher level, both for the sake of compensating for the loss sustained when it was brought down below the roof, and also to obtain a greater space for the clerestory windows. This involved, again, the difficulty as to abutment, through its raising the springing of the vault above the roof of the aisles. ”

“ For each of the triangular gores of the dome we now substitute a vault, of which every vertical section parallel to the side of the square is a portion of a circle of the same diameter with those raised on the sides, while the angles of the intersection of these newly generated vaults are themselves semicircles. It is a perfectly accurate geometrical figure, none of whose salient lines are other than portions of circles, though the ridge or crown lines now become elliptical. It is a most useful development, as being much stronger than the ordinary groined vault. ”

“ Their use is to strengthen the angles of the dome, and to augment its power of resistance to the weight of the lantern which crowns it. They do not support the vault as the ribs of a Gothic vault do. Being composed of very deep voussoirs, they have more strength to withstand thrusts, as well as to bear crushing weight, than the enclosing shells have, and thus to some extent they may hold these shells in. ”

“ Such floors exposed the keep to be burned, and once well on fire it would certainly burn till it was gutted. The basement is now and then vaulted, but the vaulting is very rarely original, and when it is so the keep is late. The vaulting at the Tower and at Dover is modern brickwork; the Ludlow vault seems Early English; that at the lower part of Carlisle, that of Porchester, Brougham, Bowes, and Richmond, Decorated; the vaulting at Middleham, Newcastle, and Mitford may be original. ”

“ In Figure 21 it will be seen that the vault is well abutted by the roof of the portico, and by stepped rings of masonry [45] over the haunch, while in Figure 22 the drum is raised high above the encircling portico, and the vault is sprung from its top, and has no abutting rings. The architect appears to have realized that such a scheme would be unsafe on a large scale, for in the one which he prepared for the dome of St. Peter’s he took care, as we shall see, to provide strong abutment. ”

“ The central area is covered with a circular vault which by most writers is called a dome, but it is not a dome; it is a vault of essentially Gothic form, like two early Gothic apse vaults joined together (Fig. 11) . It rests on pendentives, and is enclosed by a cylindrical drum, which forms [28] an effective, though not a logical, abutment to its thrusts, and is covered with a low-pitched roof of masonry having a slightly curved outline. ”

“ Vaults were built sometimes of brick, sometimes of cut stone; in a few cases even of earthenware jars fitting into each other, and laid up in a continuous contracting spiral from the base to the crown of a dome, as in San Vitale at 123 Ravenna. Ingenious processes for building vaults without centrings were made use of—processes inherited from the drain-builders of ancient Assyria, and still in vogue in Armenia, Persia, and Asia Minor. The groined vault was common, but always approximated the form of a dome, by a longitudinal convexity upward in the intersecting vaults. ”

“ The vault ribs and the vaults themselves were now also made lighter. And finally the ribs were more closely grouped at their springing—being made to interpenetrate, more or less, by which means the pressures were concentrated to the utmost, while the sustaining shafts and piers, for which the best materials were selected, were reduced to a minimum of thickness. As this development of an independent framework progressed, the intervening walls, now no longer needed for the stability of the fabric, were also reduced in thickness ”

“ A consistent exterior for such a vault would not, of course, be an unbroken drum, though a perfectly Gothic circular vault might be thus enclosed within a drum. A consistent external form would require salient buttresses against the lines of thrust, and the intervals between these buttresses would be open, as in a Gothic apse. ”

“ It is impossible for a dome of any kind to have the character of a Gothic vault. The difference between the two is fundamental. A Gothic vault is a vault of concentrated thrusts, and it requires effective concentrated abutments. A dome is a vault of continuous thrust, and for sound construction it requires continuous abutments, as in the Pantheon. Whatever use the ribs of Brunelleschi's vault may have, they do not, and cannot, perform the function of the ribs in Gothic vaulting. ”

“ At the first glance this vault seems to be built with ribs like that of Amiens or that of Reims, as shown in the plates of Chapter IV; but the network of projecting ribs in the Gloucester vault is a simulacrum only. The vault is a solid stone shell, homogeneous, and built of large pieces. Plate XXXIV shows the vault of the choir-aisle of Peterborough cathedral seen as looked at from below. The joints of the stones can be made out: they have no relation to the system of mouldings and panels. ”

“ The lower walls of the interior of the square beneath this vault have an order of pilasters, and over the entablature of this order are arched windows, one on the north and the other on the south side, each of which has a mullion and jamb shafts of the Certosa tapering type, and pseudo-Gothic tracery. Most of the details of this interior are of stone, which give it a more monumental character than the buildings before noticed have. The outside is of brick, the square part being plain, with simple angle buttresses, and crowned with a cornice of classic profiling. ”

“ The wall above the entablature is plain and unbroken, except by a round-arched window over each bay of the ground story, and is crowned with a heavy cornice from which the vaulting springs. We have here a structural system of imperial Roman massiveness, necessitated by the use of the great barrel vault.
After the early part of the sixteenth century Italy produced few architects of a high order of genius. ”

“ The groin-ribs, intersecting at the centre of the vault, divided each bay into four triangular portions, or compartments, each of which was really an independent vault which could be separately constructed upon light centrings supported by the groin-ribs themselves. This principle, though identical in essence with the Roman system of brick skeleton-ribs for concrete vaults, was, in application and detail, superior to it, both from the scientific and artistic point of view. The ribs, richly moulded, became, in the hands of the Gothic architects, important decorative features. ”

“ The work is that of consummate architects, who brought to their labours the assurance born of experienced skill, and in the later part of the twelfth century, the new system had replaced all others for the construction of vaults throughout Western Europe.
The architects of the royal domain, and notably those of the Ile-de-France, had been the first to adopt the groined vault. Towards the close of the twelfth century their assimilation of the new principles, their native ingenuity, and professional hardihood alike urged them to its further development. ”