The Principles of Vaulting--_continued_.
Certain practical points concerning vaulting--Ribs of early and
late vaulting--Filling in of intermediate surfaces or
cells--Methods adopted in France and England--Sexpartite
vaulting--Crypt of Glasgow Cathedral--Choir at
Lincoln--Chapter-house, Lichfield--Caudebec, Normandy--Octagonal
kitchen of the Monastery, Durham--Lady Chapel, Salisbury--Segmental
vaulting--Temple Church--Lady Chapel, St. Saviour’s,
Southwark--Westminster Abbey--Intermediate ribs--Presbytery at
Ely--Chapter-houses of Chester and Wells--Exeter
Cathedral--Cloisters, Westminster--“Liernes”--Ely
Cathedral--Chancel, Nantwich Church--Crosby Hall and Eltham
Palace--Choir at Gloucester--Winchester
Cathedral--Fan-vaulting--Cloisters at Gloucester--King’s College
Chapel, Cambridge--Divinity Schools, Oxford--Roof of Henry VII.’s
Chapel, Westminster--Ideal of its _design_.
My last lecture brought the subject of vaulting to its full _functional_
development,--that which contains all elements whose origin can be
traced to the demands of utility, but none which have been introduced
purely for decorative purposes. In my present lecture I must supplement
what I then treated of with some cases of its application which I had
not then time to detail, and then proceed to carry on my subject into
its more distinctly decorative developments.
Before, however, I proceed further, it may be advantageous--though
construction does not, perhaps, come within the range of lectures in
this Academy, excepting so far as it exercises an influence upon
form--to say a few words on certain practical points which are
necessary to the full understanding, even of the artistic portion of the
subject we are considering.
In the earlier forms of vaulting, the entire strength lay in the
continuous arched surface, which was constructed of brick or of stone,
or of rubble bonded at intervals with brick or stone; the rubble or
stone being often of the cellular material called tufa, which was much
used by the early builders on account of its lightness as well as the
tenacity with which it united itself to the cement.
Transverse ribs were next introduced at intervals to strengthen the
wider spaces; and, at a later period, the angles were similarly
fortified.
[Illustration: Fig. 356.]
[Illustration: Fig. 357.]
These ribs, in early examples, sprang distinctly as separate arches from
the impost, the vaulting passing over them (sections, Fig. 356). At a
later period--even in round-arched vaulting--we find the practice coming
into vogue of uniting the ribs, and even the springers of the vaulting
itself, by cutting them at the base out of the same blocks of stone. We
see an early specimen of this in St. Bartholomew’s Church (Fig. 357).
When the ribs became more numerous, it often occurred that five or even
eight of them had to spring from one group of capitals; and at times
three at least (and subsequently more) from a _single_ capital. It is
clear that in such cases the three or more distinct forms could scarcely
retain their separate existence, but that being united in their lower
portions in a single block, their forms would, more or less, die one
into another. Though we can trace this process in Norman work, it was
not completely established till some time later.
[Illustration: Fig. 358.]
[Illustration: Fig. 359.]
It will be better understood by means of Fig. 358, in which a transverse
rib, two diagonal ribs, and two wall ribs meet at their common springing
line, and so intersect and unite one with another as to produce a
section at the base composed of portions of them all. Now, a drawing of
this group of ribs will at once show that their combined and united form
must extend to some considerable height above the springing; and so far
as it reaches, which is often some 8 feet or 10 feet in height, they
cannot possess an individual existence (Fig. 359). To this height, then,
it is customary to build the group of ribs in horizontal courses, and
only to commence the radiating arch-joints where the ribs clear
themselves one from another, which usually occurs at one level, though
in vaults of great irregularity one rib often clears itself at a lower
level than another.
In setting out the relative position of the ribs upon the common
springing level, great skill and judgment are requisite, or they will
clear themselves one of another so irregularly as to cause great
difficulty and needless twisting in the filling in of the vaulting
surface. If you set out on plan the side lines of two ribs (Fig. 360),
and lay down the true position of the mouldings of _one_ of them, it is
clear that, if the curvature
[Illustration: Fig. 362. Fig. 360. Fig. 361.]
of both were equal, the second rib should be set out with its back line
at an equal distance from the points at which the plans of the adjoining
lines would intersect; for, in following the curve, both would at a
given height reach a point vertically over that intersection, and so the
filling in would have a proper starting-point, which would not be the
case if they reached that vertical line at different heights. As,
however, the diagonal rib (where the ridges are level) has to travel
farther to reach a given height, its springing section has to be set
_farther back_ to make it reach the vertical line over this point of
intersection at an equal level with the transverse rib. The wall rib in
a square vault would be similarly placed with the transverse rib; but in
an oblong vault, as it would travel a _less_ distance to reach a given
level, its springing section must be placed _forwarder_ than that of the
transverse rib, and, of course, _greatly_ forwarder than the diagonal.
This is easily adjusted by drawing the curve of the back of the rib,
whose position is first determined, drawing against it the vertical line
of its intersection with the next rib, and then, from the apex point of
the adjoining rib, to draw its curve through the point of intersection,
which will give on the springing line the distance _backward or forward_
at which the springing section of that rib should be placed (Fig. 361).
The ribs of all vaulting of early date are square and flat at the back;
the vaulting, which is often very thick, passing over and resting upon
their backs. In later works the ribs were usually deeper from intrados
to extrados, and were notched, or as it is technically called,
“rebated,” to receive the vaulting, or at least the lower part of its
thickness (Fig. 362); for where the surface was not intended to be
plastered, the wrought stonework was often a thin casing covered over
above by a thicker mass of rough work. The curvature of the courses of
wrought stone enabled them to be set without the use of continuous
timber centering, and this inner facing, once finished, would itself
form a substantial centering for the outer rough vault.
At a later period this outer thickness was dispensed with as a
superfluous load. In all cases the hollow space against the wall behind
was filled in solid to a certain height to strengthen the haunches of
the vault.
The ribs now became beautifully moulded, and sometimes decorated with
carving. In early works, as at St. Cross;[52] St. Peter’s, Oxford; St.
Joseph’s Chapel at Glastonbury;[53] and in the aisles at Canterbury, the
old Norman chevron was continued in the ribs. The meetings and
intersections of the ribs at their apex were usually ornamented with
bosses, and beautifully carved. These bosses assumed many varieties of
form--sometimes a small rosette, or a little tuft of foliage, merely to
decorate the centre of the intersection without covering the mouldings;
sometimes the mouldings themselves return round a central opening, with
or without foliage; sometimes a head of part of a figure was added to
the last-named form in each angle, nearly at the plane of vaulting;
sometimes beneath such moulded boss a disk was attached with or without
foliage, as if to form a cover to the central opening; indeed, it was
occasionally actually the moveable cover of such an opening. In England
the usual form is a group of foliage covering the intersection, and
frequently containing figure sculpture. Westminster Abbey furnishes
admirable examples both of the foliated and sculptured bosses.
As regards the intermediate surfaces of the vaulting, a curious
difference is found to obtain between the methods adopted in France and
in England.
In France the courses of stone run parallel to the ridges, as would
naturally suggest itself from the original intersecting vaults (Fig.
363); while in England they often take an irregular direction, as if
suggested by placing them at right angles to an imaginary centre line of
each triangular space, though really deviating much and irregularly from
such a rule.
[Illustration: Fig. 363.]
The French seem much offended by the appearance of the English system;
and I remember feeling in the same way when I first saw the French
method. The latter seems to throw undue pressure on the diagonal ribs,
while the English mode appears to throw it more equally on _all_ the
ribs; throwing it, in fact, down into the direction of their
meeting-point.[54]
I will now describe a form of vaulting which, though it originated
during the round-arched period, seems more properly to belong to that
now under consideration. We have seen that the arches of churches were
frequently arranged in _pairs_; the piers alternating in size and
design. Supposing each arch to be about half the width of the nave, each
_pair_ of arches would form a square on the plan; and, though such a
square space may be, and often was, divided into two oblongs in the
vaulting, it is equally natural to vault it as a single square. As,
however, this leaves the alternate piers unrepresented in the vaulting,
it became frequent to carry across from this intermediate pier a single
transverse rib crossing the diagonals at their point of intersection,
and between it and those diagonals to introduce oblique vaulting cells,
whose ridges strike from the centres of the half-bays to the point of
intersection.
[Illustration: Fig. 364.]
[Illustration: Fig. 365.]
[Illustration: Fig. 366.]
Dr. Whewell, followed by Professor Willis, has given this the name of
“_sexpartite_” vaulting (Fig. 364), ordinary vaulting being
_quadri_partite, as having four cells. It is obvious that, in a square
building of two bays on each of its sides, this may be carried out on
all four sides, and thus become an _octo_partite vault (Fig. 365);[55]
or, as in the aisles of Lincoln Cathedral, it may be adopted on one side
only, and so be _quinque_partite (Fig. 366).
These forms of vaulting were most frequent during the transitional
period; that is to say, during the latter part of the twelfth century.
Thus it is used in the work of William of Sens at Canterbury, and by
Bishop Hugh at Lincoln, and preparations were made for it at St.
David’s. It was, however, continued at Lincoln in the great transept,
and in the aisles of the nave, which are of later date; and we have an
instance of it at Westminster, as late as 1250, in the Chapel of St.
Faith.[56]
The same principle was applied, in a varied form, at the east end of the
Priory Church at Tynemouth, where, though the bays have ordinary
vaulting, the eastern wall is divided into three parts, corresponding
with the windows, over which cells of vaulting are formed, converging to
the intersecting point of the compartment.[57] Curiously enough, we find
the same arrangement repeated a century and a quarter later in the crypt
of St. Stephen’s Chapel, in the Palace of Westminster.
[Illustration: Fig. 367.]
In the Lady Chapel at Auxerre the same idea is carried out still
farther, the vaulting, square in plan, having two of its sides divided
into two cells each, as on the sexpartite principle, and the other two
into _three_ each, as those above referred to, making in all a
_deca_partite vault (Fig. 367). If _all_ sides had the threefold
division, it would have become _dodeca_partite, or a vault of twelve
cells.
M. Viollet Le Duc gives a curious instance of sexpartite or septipartite
vaulting united with another form (Fig. 368), for which I know no
definite name, but which is itself a union of the groined vault with
what I have elsewhere called the square dome.
[Illustration: Fig. 368.]
I will describe the last-named vault by a comparison between those of
two corresponding chapels near the west end of Lincoln Cathedral, to the
right and left of the nave.
[Illustration: Fig. 371. Fig. 369. Fig. 372. Fig. 370.]
The two chapels are alike in plan (Figs. 369, 370),--an oblong, each
side of which is divided into two arches. They only differ in that one
has a central pillar and the other has none. The one is simply divided
into four groined vaults on the most customary principle (Fig. 371). The
other is similarly vaulted up to the line of the square, the angles of
which would be represented by the four bosses of the first-named vaults;
but from thence the diagonal ribs, instead of returning downwards on to
a central pillar, continue to rise till they meet in the middle point of
the chapel (Fig. 372). This upper portion, therefore, is the top of a
square dome; and the whole vault may be described as a square dome
penetrated on each side by two Welsh groined cross vaults. This
combination is common in the vaulting under central towers, as at
Lincoln and York; though in these cases the central portion is bounded
by a strongly-marked horizontal line defining the boundary of the
half-groins below, and the square dome above. In the chapel I have been
describing there is no such boundary-line, but the groining compartments
continue till they meet in a point at the top. This system may be
carried out with any number of bays; and we have in the Chapter-house at
York an instance of its application to an octagon. The plan of the
vaulting there is identical (or nearly so) with that of Westminster or
Salisbury, but the portion enclosed within the inner octagon, instead of
turning down to the central pillar, runs up to the point at which all
the arched lines would meet in the centre (Fig. 373).
[Illustration: Fig. 373.--Chapter-house, York.]
The relation between the vaulting of the Chapter-houses of York and
Westminster is, in fact, the same as that between the two chapels at
Lincoln just described. In each case we see how similar forms may be
covered over with vaulting nearly identical in plan--with or without a
central pillar at pleasure.
There is a parallel case in the crypt of Glasgow Cathedral, in which the
compartment is divided on three of its sides into _two_, and on the
other into _three_ arches.
This crypt is a work in which the architect would appear to have
revelled in self-sought perplexities, and to have solved them, one after
another, with singular success.
[Illustration: Fig. 374.--Glasgow Cathedral. Plan of vaulting of the
Crypt under the Choir.]
The portion of the crypt which represents the choir overhead is really
one of the most lively and amusing pieces of vaulting I know (Fig. 374).
It consists of _ten_ bays; and, as the east end is necessarily divided
into _two_ bays for the support of those above, nothing would have been
more natural than to have placed an intermediate row of columns down the
centre, dividing the whole into two ordinary ranges of vaulting. But
no, the architect would have lost his fun by any such commonplace
scheme, and _we_ should have lost a very pretty and instructive puzzle.
Beginning at the east end, he first cut off a space two bays long, then
a second of three bays long, then a single bay, then another space of
three bays, and finally a single bay at the west end; while to each of
his groups of three bays, he gave a central column, and repeated the
threefold division on its east and west sides. These square spaces,
then, each of whose sides is divided into three, became the key-notes of
his scheme, and most ingeniously and beautifully he vaulted them. The
principle followed is really, however, nothing more than an adaptation
of the ordinary mode of dividing a square into four smaller squares of
groining, to a space whose sides are divided into _three_ instead of
_two_ (A). The central square resting on the column remains unaltered,
but the sides have each _three_ cells, the transverse ribs from the
central column being bifurcated at their apices, and instead of going
across to an opposite pillar, spread right and left to the _two_
pillars, while the main diagonal ribs remain unaltered. These are met at
their apices by half-diagonals coming obliquely from the same pillars in
the sides. The result is a star-like arrangement of an exceedingly
pleasing, though at first sight, intricate character.
Adjoining one of these beautiful squares comes the compartment first
alluded to (B). It is a very parallel case to that last described. On
three sides it is the same as the Lincoln chapel, with a portion of a
square dome instead of a central column (excepting only that this has
the boundary-line), while the fourth side, having _three_ divisions
instead of two, is dealt with precisely as has been described in the
preceding case. Amongst these intricate compartments are alternated
single bays, each divided transversely into three squares of ordinary
groining; and the perplexity of the effect of the crypt arises not so
much from the difficulty of any of the forms of vaulting, as from the
constant change from one form to another, no two adjoining divisions
being alike. The whole is carried out with excellent detail, and forms a
most beautiful and interesting interior.
[Illustration: Fig. 375.--Choir, Lincoln Cathedral.]
The subject of puzzles in vaulting suggests a notice of that of the
choir at Lincoln, where the architect (De Noyes) seems to have put
himself out of the way to make an easy matter difficult; for, instead of
groining his oblong bays in the usual way, he has made each cell strike
obliquely to points dividing the central ridge of the bay into three
equal parts (Fig. 375); so that neither the cells nor the diagonal ribs
from either side ever meet one another, but each cell is met by an
intermediate or an oblique transverse rib from the opposite side.
Professor Willis, in his peripatetic lecture there in 1848, called the
architect “a crazy Frenchman,” it being then thought that he had been
brought over by Bishop Hugh of Burgundy; but it has since been
discovered that he was a member of a Norman family long settled in
Lincolnshire; and the beauty of his work is such that we may well
excuse this freak of eccentricity, and wish that this form of craziness
was more prevalent amongst ourselves!
A curious effect is produced by carrying vaulting out accurately in a
circular aisle or corridor, where it gives the diagonal ribs a twisted
line, bending them out of the vertical plane. This is well seen in the
apsidal aisle in the Cathedral at Bourges, both in the church itself and
the crypt.
I will only notice two or three more varieties of this stage of
vaulting, and those of a miscellaneous character.
The Chapter-house at Lichfield is an elongated octagon (Fig. 376), one
of its sides on either hand being double the length of the others, and
divided into two bays. The vaulting is a curious elongation of that of
the regular octagonal chapter-house: a cell on either hand being
interpolated, and the ribs all converging obliquely to the central
pillar.
[Illustration: Fig. 376. Chapter-house, Lichfield.]
[Illustration: Fig. 377. Kitchen of the Monastery, Durham.]
At Caudebec, in Normandy, we have, though of much later date, a hexagon
vaulted much as our own chapter-houses, but with a pendant substituted
for the central pillar, and ingeniously suspended by a long stone from a
constructional vault above.
At Durham, in the octagonal kitchen of the monastery, we have a curious
piece of vaulting planned with a view to a central ventilating lantern
(Fig. 377). The ribs run from every corner at right angles to the side
of the octagon, and consequently meet the third angle from that from
which they set out, and their intersections leave an octagonal opening
equal in diameter to one side of the original octagon in the centre, and
this is strong enough to support the required lantern or louvre.
The vaulting of the Lady Chapel at Salisbury is remarkable for the
extraordinary slenderness of the columns which support it, being thin
Purbeck marble shafts of great height, reducing the width of the chapel
by cutting off a very narrow range of vaulting from either side.
Somewhat similar in idea is the vaulting of the crypt beneath the Sainte
Chapelle at Paris, where, to avoid the segmental vaulting which would be
the natural result of its limited height, the span is reduced by a range
on either side of small pillars;--in this case so near the wall as to
necessitate a great amount of stilting, and the introduction of a kind
of tracery beneath the transverse ribs to give abutment to the central
vault.
I should, in passing, mention, that segmental vaulting is very frequent
at this period, where the height is limited; and that, even where the
main arches are not so, the diagonal ribs frequently assumed that form;
indeed, it became necessary wherever the length of a diagonal exceeded
double the height of its arch.
Taking this stage of the history of vaulting as a whole, we have
peculiarly favourable opportunities of studying it here in London:
possessing, as we do, excellent examples of all its most leading
varieties.
In the Temple Church we have the curious circular aisle already
described, being a specimen of the earliest era of true pointed-arched
vaulting; while in the eastern portion, dating some forty or fifty years
later, we have the most typical specimen conceivable of vaulting, all
springing from a given level, and with level ridges. It is rendered the
more marked in character by the division of the three ranges of vaulting
by means of the pier-arches, which, coming close under the vaulting,
assume the character of enlarged ribs.
Very similar to the last-named is the vaulting of the Lady Chapel of St.
Saviour (or St. Mary Overie), Southwark (Fig. 378). The only striking
difference being the number of spans and the absence of pier-arches, so
that it assumes the form of a space divided into twelve equal and square
compartments, and carried by six similar columns.
[Illustration: Fig. 378. Lady Chapel, Southwark.]
In the choir of the same church we have an excellent specimen of
clerestory vaulting, with oblong compartments and stilted side-cells,
worked in a manner somewhat different from the usual ploughshare system.
In the eastern half of Westminster Abbey, including the transepts, we
have the vaulting of the oblong space (with ploughshare side cells), and
of the square space, and of the four-sided space of all degrees of
irregularity; we have apses of two dimensions, viz., the great apse of
the Sanctuary and those of the radiating chapels, which are as beautiful
specimens of the apse vault as can be found; we have, in the
Chapter-house, the vaulted octagon, with central pillar carried out in
noble proportions and with excellent detail;[58] while in the crypt
below is a repetition of the same vaulting, of depressed proportions,
and carried out with the severest simplicity.
[Illustration: Fig. 379.--St. Faith’s Chapel, Westminster Abbey. View
looking East.]