territory, as well as of the relationship between this Gothic style and
the Romanesque school of Perigord, may perhaps be seen in the Old
Cathedral of Salamanca in Spain.[167] Here the three western bays of the
nave are covered with ordinary domes but with diagonal ribs beneath
them, while the two remaining bays have regular domed up Anjou vaults.
The date of this cathedral, cir. 1120-1178, may, perhaps, explain this
peculiar combination as being due to an Anjou-Gothic influence
displacing one of Perigord-Romanesque, in much the same manner as such
an influence displaced the Perigord-Romanesque architecture of western
France.
SQUARE NAVE BAYS OUTSIDE OF LOMBARDY AND ANJOU
[Illustration: FIG. 21.--ANGERS, SAINT SERGE.]
Besides its use in Lombardy and Anjou, the square nave bay with four
part cross-ribbed vaults, was employed to some extent in other parts of
Europe throughout the Gothic period.[168] Some of these are churches
without side aisles, but aisles are more commonly found, divided into
rectangular bays corresponding in number to those of the nave. Of the
single naved churches, San Francesco at Assisi,[169] is a good example.
Although dating from 1236-1259, its vault ribs are still heavy and
almost square in section, as if derived from Lombard prototypes. But
they differ in being of pointed section and in not giving to the vaults
a domed up crown. In this they would seem to be examples of French
influence upon Lombard tradition.
SQUARE NAVE AND RECTANGULAR AISLE BAYS
An early church with square nave bays and ribbed vaults over rectangular
bays in the side aisles (Plate I-b), is to be found at Bury (Oise)
(Fig.
[Illustration: FIG. 22.--BURY, CHURCH.]
22). It probably dates from about 1125, and is an important monument of
the Transitional period. Its nave vaults are quite highly domed and in
this respect seem somewhat Lombard, but their pointed arches and awkward
construction indicate an effort on the part of the builders toward
reducing this doming and a dawning consciousness of the value of the
pointed arch in the construction of ribbed vaults. This is further shown
in the side aisles. Because of the rectangular shape of the bays, the
problem was presented of getting three sets of ribs of different span to
rise to the same or practically the same height. Not being thoroughly
familiar with the flexibility of the pointed rib, the builders at Bury
were naturally somewhat clumsy in its use. Thus, the diagonals were made
segmental in elevation to lower them to the level of the pier arches,
while masonry was piled on the crown of the transverse ribs, or their
voussoirs widened, to bring them up to the level of the vault
panel.[170] A few such experimental steps as these at Bury, were all
that were necessary to give the builders a mastery of the use of the
pointed arch in ribbed vaulting.
RIBS WITH CARYATID SUPPORTS
[Illustration: FIG. 23.--BURY, CHURCH.]
But there is another feature of the side aisle vaults which is worthy of
note before turning to the more developed churches which resemble Bury
in their arrangement of vaulting bays. This is the use of small caryatid
figures which appear at the springing of the diagonal ribs (Fig.
23).[171] These would seem to serve a purely decorative purpose, perhaps
to distract attention from the great size of the ribs behind them, or to
give an apparent lightness to the vault itself by seemingly placing its
burden upon such insignificant shoulders, or more probably still, the
figures served to break the transition from shaft to rib by concealing
the impost of the latter. Whatever their explanation, other examples
besides those at Bury are to be seen. Of these, the angels--now badly
mutilated--at the base of the ribs in the narthex of Saint Ours at
Loches (Indre-et-Loire) (Fig. 24)[172] are especially interesting, and
perhaps account for the tiny figures employed at the springing of the
ridge ribs in a number of churches in Anjou, such as Angers, Saint Serge
(Fig. 21), as well as for the larger figures in the apse of Notre
Dame-de-la-Couture at Le Mans (Fig. 20).[173] It may even be through the
influence of such figures as these that grotesques were used to support
the small shafts in the arcade of the triforium passage in the cathedral
of Nevers (Nièvre) (Fig. 25).
[Illustration: FIG. 24.--LOCHES, SAINT OURS.]
SQUARE NAVE AND RECTANGULAR AISLE BAYS CONTINUED
[Illustration: FIG. 25.--NEVERS, CATHEDRAL.]
Returning to the churches later in date than Bury but vaulted on the
same plan, it will be found that there are but few examples in France,
an interesting fact for which an explanation will later be
attempted.[174] The lower story of the Sainte Chapelle at Paris (cir.
1250) furnishes one of the rare examples, but here the nave and aisles
are of the same height and so do not exactly resemble the system at
Bury. Because of their narrowness, the side aisle vaults of the Sainte
Chapelle did not furnish proper abutment for those of the nave, and the
builders found it necessary to add tie-rods and even transverse half
arches forming veritable interior flying buttresses at about half the
height of the transverse ribs. This is, however, a most unusual
arrangement.
It was in Italy more than elsewhere that the method of square nave and
rectangular aisle bays was adopted. Many of the largest churches of the
Gothic period in that country were thus constructed. Among these, Santa
Maria Novella at Florence (end of the thirteenth and beginning of the
fourteenth centuries) has nave bays which are practically square, while
the cathedral of Santa Maria del Fiore (fourteenth century) in the same
city is a much larger church more strictly following the type.[175] This
vast edifice presented such a vaulting problem that the builders did not
hesitate to resort to the use of iron tie-rods to counteract the
thrusts,--a subterfuge common enough in Italian architecture, of which
the church of the Frari at Venice (after 1250) presents an exaggerated
example.
LIGHTING PROBLEMS IN NAVES WITH SQUARE BAYS
Several factors enter into the lack of popularity of the vaulting system
just described especially in the more northern countries, but the
fundamental one would seem to be the difficulty of properly lighting
churches thus covered. If an examination be made of the churches with a
single broad nave and no aisles it will be seen that in Italy, where a
comparatively small proportion of window space was necessary, the
builders were content with a single window in each nave bay as for
example, in San Francesco at Assisi. In France, on the other hand, the
light thus admitted would have proved inadequate, and in such churches
as the cathedral of Angers (Fig. 19) and Sainte Radegonde at Poitiers
two windows were introduced under each wall rib. This is, however, an
awkward arrangement because these windows do not properly fill the wall
space, and though this is better accomplished by adding a circular
window above the upright pair as was done in La Couture at Le Mans (Fig.
20), still the effect even then is not satisfactory and much solid wall
which might be utilized for windows is wasted. Moreover, in a church
with side aisles, the clerestory arrangement was still more troublesome
since important structural difficulties were involved. To raise a great
four part vault high above the aisles in order to obtain a large
clerestory was no easy task because of the excessive thrust which such a
vault exercised at its four points of support. In Italy, where the
amount of light required was not great, a very low clerestory with
small, circular windows, one to each bay, was all that was essential,
and so in such churches as Santa Maria Novella and the cathedral at
Florence the nave vault was placed at a point only slightly above the
vaults of the aisles, and its thrusts offset by simple ramping walls
beneath the side aisle roofs. Such a church in France would have been
inadequately lighted, and even if a greater structural skill permitted
the French to erect loftier clerestories than those in Italy, there
remained the difficulty of arranging the windows to get the maximum of
light and the best appearance. A single opening occupying the entire
space beneath the wall rib would have been all head and no jamb. One
upright window would have admitted too little light for a large nave,
and two windows near together not only left a great deal of wall space
unused but were most awkwardly placed in churches where one nave bay
corresponded to two bays in the aisles as in Le Mans cathedral,[176]
because they were not on an axis with the arches of the nave arcade. On
the other hand, if placed on this axis, the resulting windows were
necessarily of small size like those in such Rhenish churches as the
cathedral of Speyer where a second stage of windows has been added one
in the center above each lower pair in a far from satisfactory manner
since it brings a window above the intermediate pier.
ORIGIN OF SEXPARTITE VAULTING
In view of these facts it is at least a reasonable assumption that the
lighting problem had much to do with the discarding by the French
builders of the simple square four-part nave vault. As a matter of fact,
however, they did not exactly discard it, but evolved from it a vault in
six cells, which, while it still retained the old division of the nave
into square bays, each corresponding to two bays in the aisle, at the
same time permitted the uniform treatment of these in elevation and made
possible larger windows,--one to each aisle bay,--symmetrically placed
and, in the course of time filling the entire space beneath the wall
ribs. This six-part ribbed vaulting would seem to have originated early
in the twelfth century, in the French province of Normandy. This
province has already been mentioned as the center of a Romanesque
school, which extended over the greater part of England after the
conquest of 1066, and reached its height during the reign of Duke
William, the Conqueror (1035-1087), when a vast number of churches were
constructed, many of them of large size. These were in general wooden
roofed throughout, though, occasionally, as has been shown,[177] groined
vaults were used in the choir or aisles, or both. Toward the beginning
of the twelfth century, however, the Norman builders determined to vault
the naves of a number of these churches, among them the two abbeys at
Caen, and the result of this determination was the evolution of the true
and false six-part vault.
Like the Rhine provinces, Normandy had always been strongly influenced
by the methods of building developed in Lombardy. Whether this was due
to the presence in Normandy of such men as Lanfranc,--who was born in
Pavia in 1005 and became successively prior of Bec (1045-1066), abbot of
Saint Étienne at Caen (1066), and archbishop of Canterbury (1070-1089),
and who may have kept Normandy closely in touch with Lombardy,--or
whether there were other more powerful influences, it is impossible to
state, but in any event the architectural analogies between the two
schools are striking. This is especially true of the type of shafted
pier most frequently found in Normandy, and of the alternate system of
light and heavy supports, which, while it does not characterize all the
churches of the school, is found in many of them. Thus when the Norman
builders determined to vault their great churches at Caen, one would
naturally expect to find them turning to Lombardy for a method of vault
construction, especially since Sant’ Ambrogio at Milan had been
successfully completed at least a quarter of a century before their
determination was made. And in fact this is probably what they did. But
there were certain differences in structure between the churches of the
two schools which made it impossible for the Norman builders to adopt
unchanged, the heavy square, domed-up, cross-ribbed vaults of Lombardy.
The first of these differences lay in the fact that the Norman churches
were originally built for wooden roofs,--which may even have been in
place, in many cases, when the vaults were begun,--while the Lombard
churches were planned from the ground for their vaulting. The second
difference was, that the Norman interior system possessed a clerestory
window of considerable size centered above each of the arches opening
into the side aisles,--that is two in each wall of what would be a
square nave bay,--while the Lombard churches either had no clerestory at
all, as at Sant’ Ambrogio, or one in which the windows were small and
there was no attempt to center them as in San Michele at Pavia.
It was natural that the Norman builders should have preferred to
preserve their interior and exterior elevations as nearly as possible as
they were when only a wooden roof was used, both to avoid the expense
which would be involved in reconstruction and to preserve the large
clerestory so essential in a northern country. To vault these churches
and at the same time save this clerestory would seem to have been the
problem, therefore, which the builders set themselves to solve. That
they attempted to use the four-part vault in its solution will be seen
from an examination of the seven vaulted churches[178] still remaining
in which the old system of square nave bays is found, for in four of
these a variant of four-part ribbed vaulting was employed while in the
other three a new method was developed out of the four-part type.
A study of the two abbeys at Caen will illustrate this. Of the two,
Saint Étienne or the Abbaye-aux-Hommes (cir. 1064-1066) would seem to be
the earlier as far as its vaulting is concerned and this would seem to
date from about 1135. In its nave (Fig. 26) the alternate system of
supports is employed, though all the piers are of almost the same
section with a single shaft carried up the inner face. The aisles are in
two stories and there is a clerestory with a single window in each bay.
The nave was originally covered with a wooden roof. With this elevation
existing before the church was vaulted it is quite possible to account
for the form which this vaulting assumed. The first step must have been
to divide the nave into square bays by transverse arches,--assuming that
these were not already in place. The springing of these arches must
naturally have been governed by that of those which opened into the
crossing, and the level of their crowns, by the wooden timbering of the
roofs,--which may well have been in place when the vaults were built.
The result was that these transverse arches had to rise from a point as
low as the clerestory string-course and could only be a slightly stilted
semicircle in elevation. If the
[Illustration: FIG. 26.--CAEN, SAINT ÉTIENNE.]
bays thus constituted were to be covered by four-part vaults of Lombard
type, the next step would have been to erect diagonals of semicircular
section thus doming up the vault at the crown, but at Caen such
diagonals would have rendered necessary an entire change in the
timbering of the roof because their intersection would have risen above
the level of the trusses. Hence segmental diagonals were substituted.
Upon this skeleton of ribs, it would have been quite possible to place a
four-part vault, but the wall intersection of its panels would have cut
off the heads of the clerestory windows. Several methods could have been
used to avoid this. In the first place the severies could have been so
shaped as to cut the walls in a curve above the window, but this would
have given a flattened form to the panel and rendered it most difficult
both to construct and to support when in place. A second expedient would
have been to reduce the size of the windows but this, besides cutting
off most necessary light would have utterly destroyed the splendid
proportions between the horizontal divisions of the Norman interior. A
third method would have been to move the windows toward the intermediate
pier, but this would have destroyed the axis line of the aisle,
triforium, and window arches, and was wisely rejected. Lastly the
imposts of the ribs could have been raised, but even this would have
introduced enormous structural changes: first, because it would have
rendered necessary a change in the timbering, or else raising the entire
roof of the church; second, because it would have placed the new impost
out of level with the crossing arches; third, because it would have
greatly increased the thrust of the vault, already most difficult to
meet because of the segmental form of the diagonals and the lack of
extensive knowledge of buttressing principles on the part of the Norman
builders.
To avoid all these difficulties and still retain the windows, a new
method of vaulting was evolved. An intermediate transverse arch was
added meeting the diagonals at their intersection, and above the
triangular window cells thus formed, separate vault panels were
constructed (Fig. 26). The line of the window heads was thus left
undisturbed and the six-part vault created (Plate I-c).
FALSE OR PSEUDO-SEXPARTITE VAULTING
Of course, the foregoing suggestion that the six-part vault was evolved
from four-part vaulting is largely conjectural, but an examination of
other churches in Normandy would seem to show that the Norman builders
almost always preferred to use the simple four-part vault in a slightly
modified form whenever it was possible to do so and still retain the
clerestory windows, rather than to employ the developed six-part type.
This modified four-part vault may properly be termed false or
pseudo-sex-partite. That it was not a mere prototype of the more
developed six-part form would seem to be shown by the fact that it was
built in churches both contemporary with, and subsequent to those with
true six-part vaults.
A good example of pseudo-sexpartite vaulting, for comparison with that
of Saint Étienne (Fig. 26), is afforded by La Trinité or the
Abbaye-aux-Dames at Caen (Fig. 27). It would seem probable that the
upper portions of this church were extensively rebuilt at the time when
vaulting was added. In this rebuilding, concealed flying-buttresses were
constructed beneath the side-aisle roofs, and these, together with the
solid wall which
[Illustration: FIG. 27.--CAEN, LA TRINITÉ.]
replaces the open triforium gallery of Saint Étienne, made it possible
to raise the level of the transverse arches of the vaulting to a point
considerably above the clerestory string-course. Furthermore, since the
wooden outer roof was probably built after the vaults, it was possible
to use diagonals whose crowns were higher than those of the transverse
arches, and still place them beneath the roof trusses. With such a
skeleton of ribs as a basis, the builders proceeded to erect a four-part
vault over each nave bay, or, in other words, enclosing two side aisle
arches. Because of the higher impost of the vault ribs, the wall
intersection of the vault cells easily cleared the window heads.[179]
Curiously enough, however, the builders connected the intermediate piers
with a transverse arch having a flat wall built upon it to the level of
the crown of the longitudinal vault cells (Fig. 27). There would seem to
be several explanations of this innovation. In the first place the pier
system of La Trinité is regular, not alternate, and a greater symmetry
was obtained by having corresponding transverse arches connecting each
pair of opposite piers. Moreover such arches had been used before 1114
in the church of Saint Georges at Boscherville, and quite possibly
elsewhere as well,[180] beneath a simple wooden roof, thus tying
together the lofty clerestory walls. In the second place, such arches
had already been introduced at Saint Étienne, though for a different
reason, as has been shown, and must have proved of value in keeping the
keystone of the diagonals rigidly fixed, besides having become a
characteristic of what was perhaps the major church of the school; and
in the third place, such an arch with its wall above aided materially
both in carrying a portion of the weight of the vault to the alternate
piers and in affording permanent centering, which was needed in Normandy
even more than in Lombardy because the Norman vault crown was never more
than slightly domed up.
Once introduced, this pseudo-sexpartite vault was not restricted to La
Trinité but was, as has been said, employed in no less than four of the
seven square-bayed Norman churches. At Ouistreham (Calvados)[181]
(vaulted cir. 1160), the impost was raised as in La Trinité and pointed
transverse arches were used, thus increasing the curve of the diagonals
and improving the stability of the vault. More interesting still,
however, are the two churches of Bernières-sur-Mer,[182] and Saint
Gabriel (Calvados)[183] (both vaulted cir. 1150), for in them the
builders have clung so tenaciously to the pseudo form in preference to
the true that they have actually moved the windows of each bay toward
the intermediate pier in order to use this method without raising the
imposts. The latter is particularly interesting because of the extreme
flatness of its diagonals for which the intermediate transverse arches
must certainly have proved an added support.
The preference of the Norman builders for this pseudo-sexpartite vault,
even to the extent of moving the windows out of center to make its use
possible, may find a further explanation than any yet given in the
simplicity of its construction. A comparison of one window severy of
Saint Étienne (Fig. 26) with one at La Trinité (Fig. 27) will illustrate
this point. In the former the surface of the vault is warped on either
side of the window, while in the latter, the stone courses run almost
directly back to the wall, so that the line of intersection is
approximately the projection of one-half of the diagonal rib. Of course
this second surface was far easier to calculate geometrically and could
be put in place by less skillful builders than the warped surface
required. It had, however, the fault of being in ill accord with the
curve of the window head, but, on the other hand, it possessed the
structural advantage of distributing the thrust of the vault over a
large amount of exterior wall. This might seem a fault rather than an
advantage, were it not that in such a primitive system as that of
Normandy, thickness of wall was the greatest factor in abutment and
thrusts which were widely distributed were thus more easily met than
those which were concentrated within narrow perpendicular limits.[184]
The advantage of the warped system in thus concentrating the thrusts
was, in fact, realized only when inert stability which forms the keynote
of Norman work gave way to the carefully balanced thrusts and
counter-thrusts of Gothic architecture.
The little church of Le Petit Quévilly (Seine-Inférieure)[185] (cir.
1156) would seem at first to disprove this Norman preference for
pseudo-sexpartite vaults. The imposts of its arches are sufficiently
high to permit of such a type, yet the real six-part vault was employed.
The explanation of this would seem to lie in the geographical situation
of the church, for it is not in Calvados, like the other examples, but
in Seine Inférieure near Rouen, or in other words on the border of the
Ile-de-France, where the six-part vault had been adopted with enthusiasm
and used as early as 1140, or some fifteen years previous to the
building of Petit-Quévilly, in the large abbey church of Saint Denis.
It is also difficult to explain the use of the true form in the seventh
of the vaulted churches, which is that of Creully (Calvados),[186] but
the fact that it has the same low imposts as Saint Étienne at Caen
combined with the evident purpose of the builders to keep the windows in
the center of the bays may perhaps furnish an explanation of its
appearance here.
DEVELOPMENT OF SEXPARTITE VAULTING
The true six-part vault, as used in Saint Étienne, was far from being
perfect. In the first place, it possessed a number of inherent
structural faults. These lie chiefly in the unequal distribution of
thrusts, and the unequal size of the panels into which the vault is
divided. From an aesthetic point of view, two other faults might be
added: first, the decrease in the apparent length of the nave, due to
the fact that it was divided into a few large bays, instead of twice as
many smaller ones; and second, the fact that the crowns of the vault
cells above the windows do not run out perpendicularly from the
clerestory wall but at an awkward angle, thus greatly injuring the
symmetry of the bays. Yet in spite of these drawbacks, which were common
to all six-part vaulting, this system had a long period of popularity.
There are, however, certain structural weaknesses in these early Norman
vaults which were largely due to lack of experience on the part of the
builders, and not to the form of the vaults themselves. Wall ribs were,
for example, omitted, and the diagonals were made of segmental section,
thus rendering unnecessarily severe the thrusts of the vaults. Moreover,
such a church as St. Étienne was not planned from the ground for
vaulting and the piers had not the proper arrangement of shafts. Last of
all, the intermediate arches were of a rather ugly, stilted character,
possibly so constructed with an eye to a better distribution of light,
but in any event presenting an awkward appearance. All these faults were
gradually overcome in the Transitional and Early Gothic churches of the
Ile-de-France.
SEXPARTITE VAULTING IN THE ILE-DE-FRANCE
That it should have been this province which favored the six-part system
is most curious, for at a date almost contemporary with St. Étienne at
Caen, ribbed vaults of rectangular plan had probably been constructed
over the naves of Saint Étienne at Beauvais and the abbey church at
Saint Germer-de-Fly (Oise) (cir. 1130-40). That this method was
abandoned in most of the remaining Transitional churches would seem to
have been due to the fact that the vaults of Saint Étienne at Beauvais
fell in, and those of Saint Germer did not prove very secure.[187] Such
builders as the Abbot Suger of Saint Denis, therefore, may very
naturally have looked to Normandy for a method of vaulting, since the
vaults of Saint Étienne at Caen had at least remained in place.
Whatever the cause of its introduction into the Ile-de-France may have
been, the six-part system was used at Saint Denis (Seine) (1140-1144)
and soon became the favorite method throughout the neighboring region.
Unfortunately Saint Denis and two other important churches of the
Transition, the cathedrals of Senlis (Oise) (cir. 1150) and Noyon (Oise)
(cir. 1140), which would undoubtedly have illustrated the progress in
six-part vaulting, no longer have their original vaults, and the
cathedral of Sens (Yonne) (1140-1168) (Fig. 28) remains as perhaps the
most important example of the early developed type.[188] Its vaults show
the great advance made in construction since the completion of Saint
Étienne at Caen. The diagonals are semicircular instead of segmental
arches, and the transverse ribs are pointed and all of similar curve,
giving a more symmetrical appearance and greatly reducing the thrusts.
Furthermore the piers are profiled from the ground according to the load
which they are to carry, and, last of all, a highly stilted wall rib is
added over each clerestory window, completing the skeleton of the vault
and making possible a larger expanse of glass and more satisfactory
illumination for the interior. Of course, the use of the flying
buttress, which had been introduced a short time before Sens was built,
contributed enormously to the advancement of vault construction and in
large measure explains such an improved form of vaulting as this is. In
fact, a heavy clerestory wall was no longer essential to the support of
the vault and it was only the fact that a large expanse of glass was not
safe from the pressure of the wind, which prevented the clerestory
windows from occupying the entire
[Illustration: FIG. 28.--SENS, CATHEDRAL.]
space beneath the formeret. With the invention of tracery, what little
wall remained, was to disappear. A further advance is shown in the
decidedly stilted form of the wall ribs, which (Fig. 28) concentrate all
the thrust of the vault upon a very narrow strip of exterior wall where
it was admirably met by the flying-buttress.[189] In fact, the system at
Sens might be considered perfected were it not for the unnecessary size
of the ribs, especially those running transversely. It remained for the
builders of the cathedral of Notre Dame at Paris (begun 1163) to reduce
all the ribs to the same size, and for the builders of the cathedral of
Bourges (Cher) (begun 1172), still further to reduce all but the
transverse arches and to employ the vault upon a scale even greater than
that of Paris. In fact, Bourges marks the high water mark of this system
of vaulting and by the beginning of the thirteenth century it was in
general, entirely given up[190] in favor of the four-part cross-ribbed
vault of rectangular plan, which regained its supremacy in the
Ile-de-France after the introduction of the flying-buttress with the
protection which this afforded against such a catastrophe as that which
probably befell Saint Étienne at Beauvais.
Although employed to a much greater extent in France[191] than
elsewhere, almost every country in Europe possesses a number of churches
with six-part vaults. Thus William of Sens introduced the system into
England, where it appears in Canterbury cathedral choir (1175) and later
in Lincoln transept[192] (cir. 1215). Italy possesses many examples,
among them the large churches of San Francesco at Bologna (cir. 1240),
the Certosa of Pavia (1396), and the small church of Corneto-Tarquinia
(Roma)[193] where the vault curiously enough appears over two bays of
rectangular plan which divide what would otherwise be practically a
single square nave bay.[194] Examples in other countries might be cited,
but in no case would they differ materially from the French prototypes.
VARIANTS OF SEXPARTITE VAULTING
The fact that six-part vaulting declined rapidly in favor toward the
beginning of the thirteenth century, and thus before the era of
complicated vaults had begun, probably explains the few variants from
the standard type. Of these, the simplest consists in the addition of a
ridge rib along the longitudinal vault crown. This appears in one bay of
the choir of Lincoln cathedral[195] (Fig. 35), where the crown line is
horizontal, and in the great transept of the same church where it rises
and falls in accordance with the doming up of the central keystone. The
small church of Saint Jacques at Reims (Marne) (1183) (Fig. 29) presents
a still better example of this irregular ridge rib. The vault of Saint
Jacques would seem from its general appearance to be based upon Anjou
models and it is not surprising to find its possible prototype in the
church of La Trinité at Angers (Fig. 30). The reason for the employment
of the extra rib is probably twofold: first, to lessen the size of the
transverse panels; and second, to render the arrangement of the ribs and
severies more symmetrical. In England, it is quite possible that it
served as a cover-joint as well, but in France this would not seem to
hold true, at least in La Trinité, where the stone courses are laid with
as much care as those in the simple four-part vaults of Angers cathedral
(see Fig. 19).
[Illustration: FIG. 29.--REIMS, SAINT JACQUES.]
La Trinité at Angers (Fig. 30) is also an important variant of the
six-part vault because the impost of its intermediate rib is raised to a
considerably higher level than that of the principal transverse arches
and the intermediate rib itself is highly stilted. This would seem
further evidence that the six-part vault was evolved from the four-part
vault in an effort to make the arrangement of the windows more
symmetrical in a single nave bay corresponding to two bays in the
aisles;[196] for if La Trinité with its series of side chapels, two to
each nave bay, had been vaulted in the usual Anjou style and the windows
left as they now stand on the axis of each chapel arch, their heads
would either have been cut by the wall line of a four-part vault or
would have appeared awkwardly placed beneath it. The addition of an
intermediate transverse arch and the conversion of the vault into
sexpartite form restored the symmetry of piers, arches, and windows. In
order, however, to obtain as much light as possible and to produce the
effect of square nave bays, these intermediate transverse ribs were
stilted and their imposts raised. Nor was this stilting confined to
Anjou. It appears a number of times elsewhere often in churches where
the ridge rib was not employed for example, in the cathedrals of Bremen
and Limburg[197] in Germany, and in those of Ribe,[198] and Viborg in
Denmark.[199]
[Illustration: FIG. 30.--ANGERS, LA TRINITÉ.]
The church of the Certosa of Pavia in Italy (1396) has six-part vaults
of similar type but presents a curious arrangement of square nave bays
corresponding to rectangular bays in the side aisles (Plate I-d).[200]
The intermediate transverse arches, therefore, rise from corbels above
the crowns of the side aisle arches, a fact which explains their higher
imposts. Why such a vault should have been used can again be explained
by the desire to obtain the best possible arrangement of windows.
Five-part vaults had already been used in the aisles of the Certosa to
get square flanking chapels, and it was natural that the builders should
have wished to have a clerestory window corresponding to each exterior
bay of the church. The fact that square nave and rectangular aisle bays
were used at all would seem to have been due to the Italian fondness for
this system which caused the least possible obstruction of the church
interior by piers. The only curious feature is, therefore, the use of
the six-part, instead of the more natural four-part, vault.
A somewhat similar arrangement with the substitution of two four-part
vaults for the six-part vaults of Pavia is to be seen in the cathedral
of Magdeburg,[201] where the same combination of nave and aisle bays
occurs. The builders, like those of Pavia, first subdivided the outer
longitudinal cells of the side aisle vaults by a half rib in order to
obtain two windows instead of one, which would necessarily be of rather
clumsy shape or of small size were it placed below the long, low wall
rib of a simple rectangular four-part vault. Then to make the nave bays
and clerestory windows correspond to those of the aisles in exterior
elevation, as well as to obtain better window space, they constructed
two rectangular four-part vaults over each square nave bay with their
intermediate transverse rib resting on corbels above the aisle arches
(Plate I-e).
EIGHT-PART VAULTING
There is one more important variant of the six-part vault which is
especially interesting and unusual. It appears in the church of Saint
Quiriace at Provins (Seine-et-Marne) (cir. 1160) (Fig. 31)[202] and
[Illustration: FIG. 31.--PROVINS, SAINT QUIRIACE.]
consists in a division of the nave into great square bays each
corresponding, not to two, but to three square bays in the side aisle
(Plate I-f). The divisions thus formed are covered by what is really an
eight-part vault, which is precisely like six-part vaulting except that
there are three instead of two window cells in either side of each bay.
Needless to say the immense size of the transverse triangular severies
thus created presented a structural problem of much difficulty, and it
is not surprising that such a vault was but seldom imitated,[203]
particularly as the great discrepancy in the size of the vault cells and
the awkward angles formed by their crowns give a decidedly unpleasant
appearance. Nevertheless, there is one instance, at least, in which this
system was not only imitated but transformed into a ten-part vault. This
was at Boppart, Germany,[204] where the thirteenth century church has
vaults with four window cells and but a single pair of diagonals. To
break up the two remaining triangular severies, added surface ribs were
introduced (Plate I-g).
RECTANGULAR NAVE BAYS WITH FOUR-PART CROSS-RIBBED VAULTS
While the builders of Normandy were developing the sexpartite system
just discussed, those of the Ile-de-France were experimenting with the
simple four-part cross-ribbed vault of rectangular plan (Plate I-h). As
in Normandy, the earliest churches of the province were in the main
wooden roofed basilicas like the Basse-Oeuvre at Beauvais. When groined
vaults first appeared in the Romanesque period, they were generally
employed only in the side aisles, as at Morienval,[205] and if one may
judge from these vaults, which have unfortunately been rebuilt, they
were of slightly domed up section somewhat like those of Lombardy and
the Rhenish provinces. Toward the beginning of the twelfth century,
however, when the central power had been greatly strengthened under
Louis VI. (1108-1137), there began a marked architectural advance which
was destined to render this backward province the most important of all
in the development of Gothic architecture. One of the earliest churches
to mark this advance was Saint Étienne at Beauvais (probably early
twelfth century) (Fig. 32), which, if one may judge from the form of the
piers and the ribbed vault of the side aisles,[206] was planned from the
foundation for vaulting throughout. Unfortunately the original vaults of
the nave, if such existed, are no longer in position for they either
gave way from lack of support, a natural supposition since they had no
other abutment than the weight of the clerestory walls, or else they
were so injured by the fire of 1180 that it was necessary to replace
them by the existing vaults of the late twelfth century. These, while
they do not make up for the loss of their predecessors, are nevertheless
important because of their early date. They are antedated, however, by a
number of very important churches which still retain, in part at least,
their original vaulting.
FIG. 32.--BEAUVAIS, SAINT ÉTIENNE.
IRREGULAR FOUR-PART VAULTING OF DURHAM CATHEDRAL
The first of these is the English cathedral of Durham. The date of its
vaults is still the subject of a decided controversy, but whether they
were built between 1093 and 1133 as Bond,[207] Rivoira,[208] and
Moore[209] believe, or are later than those of Saint Denis, which is the
claim of Lasteyrie,[210] they are of sufficiently early date to be
important in a
[Illustration: FIG. 33.--DURHAM, CATHEDRAL.]
discussion of rectangular four-part vaulting. Those over the nave (Fig.
33) are especially interesting and furnish a unique variant of the
standard type. It was the apparent intention of the builders to roof the
nave with wood and for this purpose heavy transverse arches were
constructed between the alternate piers. When vaulting was determined
upon, the nave was therefore already divided into square bays each
containing two clerestory windows on a side. To vault these bays the
builders might naturally have been expected to adopt the Lombard system
of simple four-part vaults, but here in Durham, as in Saint Étienne at
Caen, the impost level of the transverse arches was so low that a
four-part vault would have made impossible the retention of the windows
already in position above each nave arch. As these were absolutely
essential in the north of England for lighting purposes, and also most
important in preserving the symmetry of the bays, a change either in
their size or position would have proved impractical. The six-part vault
was the Norman method of solving a similar problem. But the builders of
Durham invented a new system, made up of two rectangular cross-ribbed
vaults in each bay, their intermediate supports afforded by corbels, and
their alternate transverse arches omitted (Plate I-i). This omission of
the intermediate rib gives a very unusual character to the vault but it
preserves the alternate system with square nave bays so popular in
Norman work, and at the same time has a great advantage over the
six-part vault in that the transverse crown line of the window cells is
perpendicular to the outer wall. The panels are therefore more
symmetrical in elevation and the thrusts are more evenly distributed
from pier to pier. The large central severy, however, afforded a
difficult surface both for construction and support, and it is not
surprising that the system was not repeated. As in the early ribbed
vaults at Caen, wall ribs were not employed at Durham, and the abutment
was provided only by flat pilasters and concealed flying buttresses,
some of full and some of half arched form.[211]
EARLY FOUR-PART RIBBED VAULTS IN NORMANDY
That the rectangular four-part system of vaulting was developed in
Normandy, as well as in England and the Ile-de-France, and very possibly
independently of both, is proved by the early twelfth century abbey
church of Lessay (Manche) (cir. 1130).[212] If the vaults of Lessay are
an independent development it is hardly possible to see in them anything
else than another effort to vault a church with square nave bays and yet
provide the best possible vaulting to fit above the windows. A glance at
the choir[213] will show that the alternate system was here employed
just as in Saint Étienne at Caen, yet the builders introduced two
four-part vaults instead of one of six-part type in each bay.[214] The
transverse arches are still semicircular and the vault is somewhat
rudimentary. The system as a whole may be considered as a fourth
method[215] of the Norman builders to preserve their clerestory intact
and still vault their churches. A slight advance is shown in the vaults
at Pontorson (Manche) (middle of twelfth century). This is, however, a
small church without side aisles and its vaults are in almost square
bays with pointed transverse arches and considerably domed up at the
crown. Wall ribs are still lacking as at Durham and Lessay.
TRANSITIONAL FOUR-PART RIBBED VAULTS IN THE ILE-DE-FRANCE
The abbey church of Saint Germer-de-Fly (Oise) (cir. 1140), which still
retains its original vaults in the choir and two eastern bays of the
nave, presents another and perhaps more important example of rectangular
four-part cross-ribbed vaulting. Its structural arches are of pointed
section, and the piers and walls are strengthened by concealed
flying-buttresses beneath the wooden roof of the triforium.[216] These
are similar to those which have already been noted in La Trinité at Caen
and in the nave of Durham,[217] but the vaults are superior in
construction to those at Durham and are also provided with transverse
arches between each rectangular bay. With the aid of this concealed
buttress and the retention of the heavy Romanesque walls and small
openings the vaults of Saint Germer were kept from falling, and it was
doubtless this fact which led to the extension of the four-part system
until it rivaled and at length became more popular than the six-part
vaulting imported from Normandy and used at exactly the same period in
the church of Saint Denis. A number of elementary features still
remained at St. Germer, however. The transverse arches are but slightly
pointed in section, the ribs are unusually heavy, and the diagonals of
the choir bay are supported upon corbels[218] showing that the shaft
arrangement was not yet in accord with the ribs to be carried.
A gradual development of the flying-buttress, and of the compound pier,
a reduction in the size of the ribs,[219] and many other structural
refinements rapidly followed one another in the period subsequent to the
construction of Saint Germer and led to the perfection of rectangular
four-part vaulting. The cathedral of Soissons (Aisne) (cir. 1212 on)
(Fig. 67), for example, shows a considerable structural advance over
Saint Germer. Its ribs are more decidedly pointed though still somewhat
heavy and there is no hesitation in raising the impost of the vault far
above the clerestory string-course, since its thrusts are easily met by
exterior flying-buttresses.
DEVELOPED FOUR-PART RIBBED VAULTS
It is in the cathedral of Amiens (beg. 1218) (Fig. 69), however, that
the four-part vault reaches its most daring if not its most perfect
form. Here the builders constructed a vault similar to that of Soissons,
but rising over one hundred and forty feet from the pavement. Its ribs
are perfectly proportioned and finely moulded and the buttress system is
completely developed. One awkward feature does, however, appear in the
fact that the builders, perhaps, in order to concentrate the thrusts of
the vaults upon the narrowest possible strip of outer wall, have made
the wall intersection of the window severies follow an irregular curve
which does not correspond to that of the wall rib in the portion from
the impost to a point near the haunch. In spite of this defect, the
cathedral of Amiens may well be considered as marking the highest
development of rectangular ribbed vaulting. A study of other Gothic
churches will disclose few, if any, improvements, either in appearance
or construction, and many of the finest closely resemble this
masterpiece.
THE CURVE OF VAULT RIBS
Such a study will, however, show a decided difference in the elevation
of the transverse ribs and consequent shape of the vaults, which is
worthy of some notice. If, for example, a triangle be inscribed beneath
a number of these transverse arches, it will be found that the angles
inside its base vary from about fifty degrees in Saint Germer-de-Fly,
Rouen cathedral and Beverley Minster;[220] to fifty-five degrees in
Soissons, Amiens, Salisbury, and Milan cathedrals, and Westminster
Abbey; and even to sixty degrees in the cathedrals of Cologne and Reims.
Moreover there is a great difference in the curve of these same
transverse ribs. Those in Saint Germer, Beverley, and Rouen closely
approach a semicircle, those in Amiens and Salisbury are much more
pointed, but made up of two arcs without, however, a long radius with
the resulting flattened appearance to be noted at Cologne and Reims and
more decidedly at Milan. All this would seem to indicate that the
elevation of these ribbed vaults,--and this is true of six-part and
complex vaults as well,--was largely a matter of individual taste with a
tendency to favor the form used at Amiens. The reason for the employment
of very sharp curves like those of Reims, Cologne and Milan, was
doubtless due to the appreciation on the part of the builders of the
fact that such curves greatly reduced the outward thrusts, rather than
to any idea of beauty of appearance to be gained, for in this they are
perhaps inferior to the less pointed examples.
RECTANGULAR FOUR-PART RIBBED VAULTS IN CHURCHES WITHOUT SIDE AISLES
[Illustration: FIG. 34.--ALBI, CATHEDRAL.]
The use of rectangular four-part ribbed vaulting was not confined to
churches with side aisles, but appears also in those with a single broad
nave. It is the method employed in the Sainte Chapelle at Paris (fin.
1248), where there are simple salient buttresses, and there is a
splendid example in the Cathedral of Albi (Tarn) (begun 1282) (Fig. 34),
where the nave has a very wide span and is flanked by chapels in two
stories between heavy pier buttresses which are thus enclosed in the
church in a truly Byzantine manner. In the smaller church of Saint
Nicholas at Toulouse these buttress chapels are in but one story and the
bays are more nearly square in plan, a compromise between the square and
rectangular systems which appears on an even larger scale in the
cathedral of Saint Bertrand-des-Comminges (Haute-Garonne) (cir. 1304).
As far as construction is concerned these vaults over a single broad
nave offer no advance over those in churches with side aisles, not even
requiring a scientific system of flying buttresses to offset their
outward thrust. Their only importance lies in the very broad space
sometimes covered by them.[221]
VAULTING WITH ADDED RIBS
The simple forms of ribbed vaulting just discussed were the ones most
frequently in use during the best Gothic period. But among certain
builders, there was a tendency even in the thirteenth century to
introduce additional ribs into the vaults, a custom which later gave
rise to a vast number of complicated vaulting systems especially in
England, Spain and Germany. Even to enumerate these would be almost
impossible and a description of each is out of the question, hence only
those combinations which were frequently employed, or which gave rise to
new types, will be discussed.
ORIGIN AND USE OF THE RIDGE RIB
Naturally enough the ridge rib was the first to be added to those
already constituting the four-part vault (Plate I-j). But the vaults
thus formed should be divided into two groups. The first most frequently
found in France and already discussed in connection with the churches of
Anjou,[222] is that in which the surface of each severy has a curved
crown and the rib follows this curve, with the object, probably, both of
subdividing the large rectangular bays, of marking with absolute
exactness the crown line, and of aiding in rigidly fixing the central
keystone, or even in the case of a six-part vault, of giving the same
apparent division to the transverse severies as is found in those
running longitudinally.
Though very similar to this first type, the second, which was developed
and most used in England, is different, in that the ridge line is here
[Illustration: FIG. 35.--LINCOLN, CATHEDRAL.]
perfectly horizontal, and the main purpose of the rib is to mark this
horizontal line with absolute exactness and to give, what Bond terms a
spine,[223] to the vault skeleton. In the earliest example in England,
the transept aisle of Ripon cathedral (cir. 1170),[224] the ribs are so
small as to be purely decorative. This leaves the choir of Lincoln
cathedral (begun 1192) (Fig. 35) as the first English example of
importance in which a true ridge rib appears. It is not yet absolutely
horizontal since there is a slight curve to each severy. Its presence
would seem to be due to the peculiar form of the vault, in which the
ribs enclosing the window cells do not meet at a common point of
intersection but at two points somewhat distant from each other along
the ridge line where each pair is abutted by a single rib running to the
nearest impost on the opposite wall (Plate I-l). This arrangement, which
was probably planned to increase the amount of centering in the large
transverse panels and thus render their construction easier,[225] gives
an extra keystone in each bay and it is quite possible that the ridge
rib was introduced in order to unite these intersections and fix them in
a straight line. It does not appear in the window cells where it would
of course have been at an awkward angle with the outer walls.
Once introduced into English architecture the ridge rib was destined to
play a most important part in its development. In the first place, it
provided an easy method of assuring an absolutely level and straight
ridge line and was thus especially welcome to English builders, who had
been trained in the construction of vaults which were never more than
slightly and often not at all domed up, and who were, besides, rather
inferior masons, and not particularly skillful in making their masonry
courses intersect in a perfect manner. In the second place, it furnished
admirable abutment for tiercerons or intermediate ribs,[226] which were
perhaps suggested by such a vault as Lincoln choir as being valuable
additions to the rib skeleton and were thereafter very generally used to
provide more permanent centering and to further reduce the size of the
vault panels.
It is, however, notable that a longitudinal ridge rib appears added to
simple four-part vaults without the introduction of tiercerons or
transverse ridge ribs at a comparatively early date in Worcester
cathedral choir (after 1224),[227] Westminster Abbey choir (1245-1260),
and Gloucester cathedral nave (1245), and that it is used in France in a
number of churches where there are no tiercerons.[228] In such cases it
serves the primary purpose of clearly marking the ridge line, which is
especially difficult to adjust in vaults with level crowns. That it was
the longitudinal effect thus produced which was desired is evidenced by
the fact that except when there were tiercerons in the longitudinal
cells, the transverse ridge rib was rarely added to such vaults (Plate
I-k). Among the very few examples are the cathedral of Tulle (Corrèze)
(twelfth century) and the fifteenth century chapel of the château at
Blois, both of them in France.[229]
TIERCERON VAULTING
The introduction of a ridge rib was only the first step in the
development of multiple rib vaulting. It was not long before the
builders, especially in England, began to add intermediate ribs or
tiercerons between the transverse arches and the diagonals. These may
possibly have been inspired by the extra ribs in the choir of Lincoln
cathedral (Fig. 35 and Plate I-l), but whatever their origin they became
a common feature of later Gothic and gave rise to what may be termed
tierceron vaulting. In the transverse vault severies, which in England
were really sections of a tunnel vault because of the level crown line,
these ribs acted largely as added centering and as decorative features.
But when used in the window cells they served another purpose as well
for they enabled the builders to convert the ordinary “ploughshare”
curve of the vaulting conoid into a series of flat panels which could be
constructed with much less difficulty as far as the laying of the
masonry courses was concerned.
Sometimes the tiercerons are used in both the transverse and the
longitudinal severies and sometimes only in one of them. Their number
also varies greatly, though of course they are always in pairs. Lincoln
cathedral presbytery (cir. 1266-1280) (Fig. 36) affords an example of a
single pair in each of the large transverse severies with none in the
window cells (Plate I-m), while Chester cathedral chapter-house (first
half of the thirteenth century), and Worcester cathedral nave (cir.
1350-1377) (Fig. 89) are rare examples of the opposite arrangement
(Plate I-n).[230] To support such tiercerons as these at their crown, a
transverse ridge rib was added to the construction, sometimes as in
Chester chapter-house (Plate I-n), Lincoln nave (before 1233),[231] and
Ely presbytery (1235-1252),[232] running out only to the new keystone
(Plate I-o) and thus playing a purely structural rôle, but often
extending to the window head (Plate I-p) as in Lichfield cathedral south
transept (cir. 1220) and choir (fourteenth century). These portions of
Lichfield, together with the nave of Lincoln and the presbytery of Ely
cathedral, are also important as showing the employment of a single
pair of tiercerons in each of the four panels of the vaulting bays
(Plate I-p). This system is slightly varied in the naves of Lichfield
and Hereford (Plate I-q-r), where the true transverse arch is omitted
between the bays, but these vaults like those of Durham are merely
variants of the more standard types.[233]
[Illustration: FIG. 36.--LINCOLN, CATHEDRAL.]
The introduction of a single pair of tiercerons in each major panel was
soon followed, especially in the window cells where the surface was
warped, by the use of two (Plate I-s) and even of three such pairs
(Plate I-t). Two are found in Hereford cathedral south transept (cir.
1400),[234] and in the choir of Saint Mary Redcliffe at Bristol
(fifteenth century),[235] while three appear at Exeter (between
1280-1350) (Fig. 37). This last may well be said to mark the highest
point in tierceron vaulting,[236] and it must be acknowledged that the
decorative effect produced is most pleasing. Placed as they are over
comparatively low naves, these vaults harmonize in an admirable manner
with the clustered piers, moulded archivolts, and substantial walls
provided for their support, and carry to the crown of the vault that
wealth of moulding which lends so much of grace and charm to the English
Gothic of the Decorated period. Were such vaults used above the lofty
naves of Amiens or Beauvais, they would doubtless appear oppressively
heavy but the lowness and solidity of English construction entirely
dispels such a feeling. Of course, tiercerons are not essential members
of the vaulting system and perhaps they were better omitted altogether,
but that their usage can be vindicated from an aesthetic standpoint is
proved by such vaults as those at Exeter.
[Illustration: FIG. 37.--EXETER, CATHEDRAL.]
LIERNE VAULTING
Tierceron vaulting did not, however, mark the limit to which the English
Gothic builders were to carry their passion for added ribs and complex
design, and it was not long before short connecting ribs known as
liernes were added to the tierceron vaults. These may have been
introduced by the builders from a feeling that the tiercerons did not
have sufficient abutment, as Bond suggests,[237] but it is more
reasonable to suppose that they are the result of a striving for still
more complex vaulting forms and still more decorative patterns in vault
construction.
The combinations in lierne vaulting are of course without number and
only a few can be discussed. The simplest is that known as the star
vault (Plate I-u) in which there is a single pair of tiercerons in each
of the four main vault panels with short liernes connecting the points
of their intersection with the ridge ribs, with a point in the same
plane on each of the diagonals. A simple example occurs at Oxford in the
Proscholium[238] and one of the same general type but much elaborated,
in the choir of Oxford cathedral.[239]
It is almost impossible to classify the remaining lierne vaults under
separate heads, though there are certain characteristics which belong to
one group and not to another. For example, some, like those of the nave
of Saint Mary Redcliffe at Bristol[240] have no ridge rib, others have a
single rib like that found in tierceron vaulting. These last might again
be classified according to the number and arrangement of their liernes.
Thus in Ely cathedral choir[241] (beg. 1322) and Norwich nave (vaults
cir. 1470)[242] there are but few liernes, while in Winchester cathedral
nave (cir. 1394-1460) there is a much larger number. Still other lierne
vaults have more than one ridge rib. Of these, the choir (1337-1357),
and Lady chapel of Gloucester cathedral (cir. 1457-1489), and the nave
of Tewkesbury Abbey (Fig. 38)[243] are representative and varied
examples. All have three ridge ribs which is the standard number.
INTERPENETRATING MULTIPLE RIBBED VAULTS
In these last three churches, however, as well as in Winchester nave and
in numerous other examples not cited, there is a still more decided
change in the form of the vault than that brought about by the use of
liernes or added ridge ribs. This lies in the fact that the window cells
no longer rise to the full height of the vault, so that the entire
system is practically a reversion to the Romanesque tunnel vault pierced
on either side with lunettes, in other words, to the interpenetrating
vault. The ribs merely form a permanent centering, and generally no
attempt is made to concentrate the pressure on a narrow strip of
wall,[244] or to make use of flying-buttresses.[245] Except for the
decoration which they afford, the ribs have little structural value
though they do make possible lighter masonry in the web than would be
possible in a continuous tunnel vault.
[Illustration: FIG. 38.--TEWKESBURY, ABBEY CHURCH.]
The height of the window cells in such vaults was not at all fixed
though it was quite frequently determined by the intersection of two
ribs running diagonally from each side of the window to the second
impost on the opposite wall of the church.[246] Such window cells as
these naturally left a large central space along the crown of the vault,
which was usually decorated by extra lierne and ridge ribs.
TRACERY VAULTS
Not content with the liernes as a decoration, an innovation appears in
Tewkesbury choir,[247] Saint George’s Chapel at Windsor[248] and
elsewhere, which consists in the application of raised mouldings forming
tracery patterns on the few open spaces left between the ribs of complex
lierne vaults. It is as if the tracery of a window were applied to a
background of stone, with ribs taking the place of mullions. The
patterns are usually trefoils or quatrefoils, but other forms, as, for
example, the cross shaped flowers in the fan vaults at Peterborough
(Fig. 39) also occur.
The natural consequence of such added mouldings and ribs as those just
described was to bring about the total sacrifice of the structural
principles of ribbed vaulting to those which were purely decorative, and
it is not surprising that such a vault as that of the choir of Wells
cathedral (1329-1363),[249] in which the ribs have but the slightest
claim to structural purpose should be found even at its early date as an
example of this decadent stage in English vaulting.
FAN VAULTING
But the addition of multiple ribs lead not only to such debased vaulting
as that at Wells. It must have played a large part in the creation of
the distinctly novel construction known as fan vaulting. For in a vault
with many tiercerons, as for example, that at Exeter (Fig. 37), or
Hereford south transept,[250] the combined surfaces between the ribs is
a cross between half of a hollow sided pyramid and a cone. This is true
because, like most of the English churches, the wall rib is not highly
stilted to concentrate pressures on a narrow strip of outer wall, or to
leave a more pointed window head as in France, but it and the tiercerons
and diagonals have much the same curvature. It was natural, therefore,
that the English
[Illustration: FIG. 39.--PETERBOROUGH, CATHEDRAL.]
builders should have conceived the idea of making all the ribs of just
the same curvature but of different length according to their several
positions. This they did in Sherborne Abbey nave (vaulted
1475-1504).[251] Here the builders very logically used the shortest rib
as a measure and connected the points at corresponding distances from
the imposts on each rib with liernes. A central space was thus left,
which at Sherborne was covered by prolonging a number of the radiants
and adding a tracery of liernes and mouldings. The vault as thus
constituted is not yet of pure fan type. It was first necessary to
replace the ring of straight liernes by those of curved plan and to add
one ring above another at the various points of intersection of the
tiercerons and transverse ridge ribs, until practically the entire space
to the vault crown was filled. Thus, in certain of the fan vaults of
Peterborough (second half of the fifteenth century) (Fig. 39), there are
three such rings leaving but a small diamond shaped central space which
is largely filled by the keystone of the bay.[252] Others down the side
aisles where the bays are smaller have but a single ring and a much
larger central space. In vaults of the Peterborough type, the radiants
are continued through this central panel in a decorative way, but in the
cloister at Gloucester (before 1412) (Fig. 40), this portion of the
vault is left entirely flat and decorated with tracery patterns in
raised mouldings such as are usually found in window heads. The conoids,
also, are covered with tracery rather than continuous ribs and the term
“Fan-Tracery Vaults” might properly be used to distinguish them from the
more common type.[253]
[Illustration: FIG. 40.--GLOUCESTER, CATHEDRAL, CLOISTER.]
In the matter of construction, fan vaulting differs from any preceding
method. Its ribs are all of precisely the same curvature, their length
being determined by the position which they occupy, and they are no
longer supporting but rather decorative members. The lower portions of
some of the vaults still resemble true ribbed vaulting in that the
tas-de-charge is used, and also in the fact that the ribs still rise in
a single long voussoir from their imposts to the first horizontal ring.
But from this point to the crown, the ribs and mouldings are merely
carved in relief upon the jointed masonry, which they therefore in no
way support. In some fan vaults, as, for example, in Islip’s chapel in
Westminster Abbey,[254] and in Gloucester cathedral cloister (Fig. 40),
the rib is even carved upon the vault masonry for its entire length.
The one structural advantage which the fan vault afforded lay in the
fact that it could be built up of practically horizontal courses in a
manner to exert very little outward thrust; while the substitution of
curved, for straight liernes did away with the awkward angular
intersections characteristic of lierne vaulting. Altogether, it is both
a clever and beautiful type of vaulting well suited to the builders of
the Perpendicular Gothic period, with their fondness for intricate
decorative rather than structural problems.
PENDANTS
Because of its late development, fan vaulting was not extensively used
to cover an entire church. Nevertheless, King’s College Chapel at
Cambridge (vaulted between 1512 and 1515),[255] and Bath Abbey (cir.
1500-1540),[256] furnish two excellent examples, to which might be added
Henry VII’s Chapel at Westminster (cir. 1500-1520).[257] The latter is
essentially of fan type, though the fans are in combination with a
system of transverse arches and pendants best understood from the
photograph and drawing just cited. The vaults in the foregoing churches,
do however exhibit minor differences. For example, the transverse arches
are practically concealed in the vaults of the naves at Sherborne, and
Bath and in the east aisle of Peterborough, while they are prominent in
Henry VII’s and King’s College chapels. Moreover, in a number of fan
vaults as well as in others of different type, pendant voussoirs or
keystones are employed. These are supported by some clever building
trick and beautifully carved either as lanterns or reliquaries,--like
those of Oxford cathedral choir,[258]--or decorated with rich floral,
heraldic, or other designs. Thus they play a rôle which is largely
decorative, though one which also marks a very clever building
technique.[259]
VAULTS WITH ADDED RIBS--OUTSIDE OF ENGLAND
The vaults thus far discussed have been largely those of England, but
some of the types with added ribs, most highly developed in that country
were not without Continental examples. In France, for instance, ridge
ribs, besides being used in vaults of the domed up Anjou type already
described, are also found marking level ridges like those of the
standard English vaults. The nave of the abbey church of Souvigny
(Allier) (late fifteenth century), the north transept of the cathedral
of LeMans (before 1430), and the chapel of the Maison de Jacques Coeur
at Bourges (middle of fifteenth century) afford excellent examples of
the use of the longitudinal without the transverse ridge rib, while the
chapel of the château of Blois, and the cathedral of Tulle (Corrèze),
have already been cited as rare instances in which both were employed in
vaults with level crowns. That the French builders were even more
impressed with the decorative possibilities which these ribs afforded
than were those of England is perhaps shown by the fact that, whereas in
England this rib has carved decoration[260] only rarely as in the nave
of Lichfield cathedral it is carved in no less than three of the French
examples cited, the chief among these being Souvigny, in which a deeply
cut foliate design decorates both sides of the rib throughout its entire
length. In Spain also there is a notable example of the decoration of
both a longitudinal and transverse ridge rib in the form of a knotted
rope or scourge in the cathedral of Vizeu.[261]
Tiercerons as well as ridge ribs were freely used on the continent
though usually not at a very early date. Fine examples are to be seen in
France in such churches as those of Brou (Ain) (1506-1536), and Saint
Nicolas-du-Port (Meurthe-et-Moselle) (cir. 1505).[262] Both of these are
also of interest because their vaults still retain the domed up crown
characteristic of French construction, and because of this the builders,
to avoid the awkward rise and fall of continuous ridge ribs, have
brought these out only far enough to meet the pair of tiercerons in each
severy. Many other examples of tierceron vaulting could be cited both in
France and elsewhere, but they would add nothing of importance from a
structural standpoint.
As for lierne vaults, they, too, appear on the Continent especially in
Germany and Spain. The choir of Freiburg cathedral (second half of
fifteenth century) (Fig. 72), and the church of the Holy Cross at
Gmund,[263] show two German types, both of which resemble English vaults
which have already been discussed. In Spain, the new cathedral at
Salamanca[264] (begun 1513), the cathedral at Segovia (begun 1525),[265]
and many other churches might be cited, while in France the church of
Mézières (begun 1499),[266] and Switzerland the cathedral of Bern (cir.
1421-1598)[267] show the extent of the style, sometimes with sharply
defined domed up bays as in Mézières and sometimes a continuous vault
like that of Bern. Finally in some instances, as, for example, the
Stadkirche of Wimpfen[268] the liernes are curved giving a still more
complicated character to the vault.
Fan vaulting was unused[269] outside of Great Britain, but there are
many instances of the employment of extensively decorated vaults,
including those with pendants of somewhat English character. Among the
latter are Saint Pierre at Caen and Saint Eustache at Paris
(1532-1637),[270] while pendants of especially exaggerated type are to
be seen in the vault of one of the chapels off the south side aisle of
Noyon
[Illustration: FIG. 41.--NOYON, CATHEDRAL, CHAPEL.]
cathedral (Fig. 41). A tendency to decorate the panels is also
noticeable in a number of late French vaults, as for example that of the
chapel of Saint Jacques at Cléry (Loiret) (probably after 1485) (Fig.
42), where each of the larger divisions of a complicated lierne and
tierceron vault is decorated by a wallet and staff or a scourge in low
relief. At Rue (Somme), in the chapel of Saint Esprit,[271] there is a
somewhat similar vault with heraldic devices and floral ornament on the
panels. But even more notable are the angels in the round which have
been added for decorative purposes in four of the severies of the vaults
in one bay of the side aisle of the north transept (sixteenth century)
in Senlis (Oise) cathedral (Fig. 43). The final stage in elaborate
vaulting, is perhaps, to be seen in such a vault as that of the Chapelle
de la Vièrge at La Ferté-Bernard (Sarthe)[272] which dates from
1535-1544. Here the panels are merely portions of a flat ceiling
resting upon a series of arches arranged like ribs, but carrying a
tracery framework upon which the elaborately decorated ceiling with its
mouldings and stalactite pendants is made to rest.
[Illustration: FIG. 42.--CLÉRY, CHAPEL OF SAINT JACQUES.]
SIDE AISLE VAULTING
There now remain for consideration before closing this chapter, the
ribbed vaults of the aisles and triforia of Gothic churches. Very
naturally the general development of ribbed vaulting in the aisles
closely parallels that in the nave. In by far the larger number of
churches, the side aisle bays are square and covered with simple
four-part cross-ribbed vaults. As in the case of the nave, those of
early date have many clumsy features. Thus in the aisles of Saint
Étienne at Beauvais (Fig. 44)--which, fortunately, retain a few bays of
their primitive vaults dating from about 1125--the diagonals are heavy
(cir. 20-25 cm. thick)[273] and either square with simple bevelled edges
or of single torus section. No wall rib is found and the transverse
arches, besides being very thick, are of round-headed form, highly
stilted to bring them up to approximately the general vault level. The
vault itself is slightly domed up at the crown and besides the
[Illustration: FIG. 43.--SENLIS, CATHEDRAL, CHAPEL VAULT.]
[Illustration: FIG. 44.--BEAUVAIS, SAINT ÉTIENNE.]
[Illustration: FIG. 45.--SENS, CATHEDRAL.]
primitive characteristics just enumerated, its panels are composed of
small stones roughly joined and in very uneven courses, while the ribs
themselves are built up of short voussoirs, which are not combined at
their springing in the familiar tas-de-charge of more developed Gothic
work. The cathedral of Sens presents in its side aisles (Fig. 45), which
date from the twelfth century[274] a slightly different system. The
transverse arches are still heavy and semicircular but they are not
stilted. The diagonals rise from corner corbels--a fact which may prove
that the aisles were originally planned for groined vaulting and thus no
provision made for the cross-ribs,--and they are also semicircular, thus
giving the vault a decidedly domed up character. This makes these vaults
at Sens very similar to Lombard work and it would seem as though their
builders had the same object of saving centering by the use of ribs as
obtained in Lombardy. There is one apparent advance over those at
Beauvais in the presence of a wall rib, but this is of too wide a span
to fit under its severy, and it would seem to have been designed to mark
the wall intersection of groined rather than ribbed vaulting.
The early aisle vaults in England are generally similar to those at
Beauvais, with even less doming or none at all. The earliest would seem
to be those in Peterborough, Durham and the north nave aisle of
Gloucester cathedrals, all dating, apparently, from before 1140.
Although similar to those in Saint Étienne at Beauvais they differ in
the comparative lowness of their transverse arches, which are but
slightly stilted, and in the correspondingly reduced curve of the
diagonals, which are less than semicircles and thus do not raise the
crown of the vault. The explanation of this may very possibly be found
in the desire of the builders to avoid cutting into the level of the
triforium floor, especially at Peterborough, where this is a true
gallery, and also in their familiarity with the flat crowned groined
vault, which they had previously used in crypts and elsewhere. The form
of the diagonals is in any case displeasing, as they spring from the
shafts at an awkward angle and, furthermore, render the thrusts of the
vault excessive.[275]
Many structural refinements were, of course, necessary before these
crude vaults gave rise to the fully developed type, but these
refinements followed in general the same order as those in the larger
nave vaults. First came the introduction of the pointed arch and its use
for the transverse and longitudinal ribs in place of the semicircular
type. This change may be seen in such early vaults as those of Noyon
cathedral (cir. 1150) where pointed arches are used throughout. The
noticeable feature here is the great size of the transverse ribs
compared to that of the diagonals. This same feature continues to appear
in a gradually lessening degree in many of the churches of the
transitional period, and even in the developed Gothic of the thirteenth
century, as, for example, in Bourges and Amiens cathedrals. This may,
perhaps, be explained by the function of this transverse arch which was
not merely a centering for the vault panel, but carried a considerable
amount of the weight of the exterior buttress piers and wall pilasters
which were connected above the aisle roofs by the arch of the flying
buttress. These heavy transverse ribs also aided materially in bracing
the nave piers and tying them to the outer walls. Sometimes, as in the
beautiful aisles of Rouen cathedral, all the ribs are of the same
section, but whether they were all the same or not, such vaults as those
at Rouen and Amiens set the standard for developed Gothic side aisles.
FIVE-PART AISLE VAULTS
[Illustration: FIG. 46.--BEAUVAIS, CATHEDRAL, FIVE-PART VAULT.]
Other methods, however, were employed. Perhaps the chief among these is
the five-part vault, in which the triangular severy nearest the outer
wall in a four-part vault is subdivided by a half rib running to the
main vault crown (Fig. 46). The advantage of such a system lies in the
fact that it permits a more pleasing arrangement of windows in the outer
wall, especially in bays of rectangular plan, like those in the Certosa
at Pavia and Magdeburg cathedral already discussed, where the windows
would otherwise fit but awkwardly beneath the broad low wall rib. The
same system was also used in aisles with practically square bays, as,
for example, in the cathedral of Coutances (Fig. 82), in Saint Urbain
at Troyes and in many English churches.[276] Here, too, the explanation
is to be found in the window arrangement, especially in the English and
Norman Gothic examples, where these windows are of the slender lancet
type, which could not be satisfactorily placed beneath the comparatively
low wall rib of a square four-part vault.
MULTIPLE-RIBBED AISLE VAULTS
With the introduction of ridge ribs, tiercerons, and liernes, the side
aisles show the same changes as those which took place in the nave.
Simple ridge ribs appear, for example, in Lichfield cathedral, liernes
at Worcester, while tierceron vaults could be cited in great number. Fan
vaults, too, were used in the aisles, and have already been discussed in
connection with those of the nave. Reconstructions sometimes produced an
unusual vaulting system like that of Beauvais cathedral (cir. 1284),
where transverse arches with tracery spandrels were added across each
original aisle bay, giving the vault a pseudo-sexpartite character. True
six-part vaulting was by its very nature ill-suited for use in the
aisles and is very rarely found. There is an example, however, in
Magdeburg cathedral.[277] A desire for novelty also seems to have been
the cause of unusual vaults, such as those of Bristol cathedral choir
aisles,[278] in which low transverse tracery arches separate the bays
and carry a system of ribs which subdivide each bay into two rectangular
four-part vaults running lengthwise of the aisle.
TRIFORIUM VAULTING
Although similar in plan to the side aisles, the triforia were apt to be
a little later in being given ribbed vaults. In the abbey church of
Saint Germer-de-Fly (Oise) (cir. 1140) and in the choir of La Madeleine
at Vézelay (Yonne) (cir. 1160 or 1170), for example, the triforium is
not only left with groined vaults but is also constructed with
round-headed arches, although both the ribbed vault and pointed arch are
used in the aisles. This peculiarity may be due to the fact that groined
vaults were easier and cheaper to construct over a low space like the
gallery than a ribbed vault would have been, because they involved less
careful stone cutting than was required for the ribs. Moreover, since
the chief object of the transitional builders in using the ribbed vault
would seem to have been to save centering, their object would not have
been especially well served in the triforia, which were kept low to
avoid detracting from the clerestory and therefore required but little
centering compared to that which would have been needed for groined
vaults in the side aisles. Another system with possibly a similar reason
for its use appears in Mantes (Seine-et-Oise) cathedral (end of twelfth
century), where the aisles are ribbed and surmounted by a triforium with
transverse tunnel vaults, a most exceptional arrangement.
[Illustration: FIG. 47.--SENLIS, CATHEDRAL.]
It was only when the triforium began to play a larger rôle in the church
plan, when it was perhaps used for congregational purposes, that its
vaulting began to develop like that of the aisles. Thus in the cathedral
of Senlis (Oise) (cir. 1150) (Fig. 47), the triforium though
comparatively
[Illustration: FIG. 48.--LAON, CATHEDRAL.]
low, is a veritable second story above the side aisles with its own good
sized windows. Its vaults are still of rather primitive ribbed type. The
transverse arches, though pointed, are heavy, and to avoid the flattened
curve which the diagonals would otherwise have, the vault is given a
domed up crown. The cathedral of Laon (Aisne) (cir. 1170) (Fig. 48)
possesses a triforium of slightly greater height but still retaining
excessively heavy ribs and domed up vaults. The triforia of the naves of
Noyon (Oise) cathedral (cir. 1150-1180) and of Notre Dame at
Chalons-sur-Marne (Marne) (1157-1183) show a gradual reduction in the
size of these ribs, all of which finally become of practically equal
section in the triforium of the cathedral of Notre Dame at Paris (beg.
1163), where the doming up of the crown also disappears to a large
extent and where the gallery itself is nearly as lofty as the side
aisles. After the beginning of the thirteenth century, triforia rapidly
decline in popularity and are but rarely found except in Normandy, where
there are beautiful examples in such churches as Saint Étienne at Caen
choir rebuilt in the first quarter of the thirteenth century. Owing to
its early decline in popularity, the triforium never presents those
complex vaulting systems of the late Gothic period which have been
described as appearing in the nave and aisles.
NAVE AND AISLES OF EQUAL HEIGHT
In closing this chapter brief mention should be made of the series of
churches in which the aisle vaults are nearly or quite as high as those
of the nave, which they therefore aid in supporting. Among the numerous
examples of such churches, the cathedral of Poitiers (Vienne) (cir. 1160
and thirteenth century) illustrates the type in which the vaults of the
aisles are slightly lower than those of the nave, while Saint Serge at
Angers has all the vaults at exactly the same level. Both are of Anjou
type but this is due only to their geographical situation, for the
system was widely extended.[279] In Germany there is a fine early
example in Saint Elizabeth at Marburg (cir. 1235),[280] with vaulting of
simple Gothic character, while the church of the Holy Cross at
Gmund[281] is covered with vaulting of complex lierne type. Except for
the change in interior elevation which the system brought about and the
fact that it removed the necessity for flying-buttresses, it did not
show any special progress along structural lines. It must be
acknowledged that the churches thus constructed possess a most pleasing
effect of spaciousness in their interior elevation, though this is
offset by the lack of direct light in the nave. A final example of a
church similar to those mentioned above but with a new vaulting system
is afforded by Saint Florentin at Amboise (Indre-et-Loire)
(fifteenth-sixteenth century). Its aisles are very narrow and are
covered by transverse tunnel vaults in much the same manner as a number
of Romanesque churches already discussed, except that the nave is here
roofed with a ribbed vault. It is but a variant of the standard vaulting
types described in this chapter.