CHAPTER I

MEDIAEVAL CHURCH VAULTING

PRINCETON MONOGRAPHS IN ART AND ARCHAEOLOGY V

MEDIAEVAL CHURCH VAULTING

BY

CLARENCE WARD

ASSOCIATE PROFESSOR OF ARCHITECTURE, RUTGERS COLLEGE

LECTURER ON ARCHITECTURE, PRINCETON UNIVERSITY

PRINCETON UNIVERSITY PRESS

PRINCETON

LONDON: HUMPHREY MILFORD

OXFORD UNIVERSITY PRESS

1915

Copyright, 1915, by

PRINCETON UNIVERSITY PRESS

Published November, 1915

To A. M.

WITH THE LASTING AFFECTION OF THE AUTHOR,

WHO IS INDEBTED TO HIM FOR MUCH INSPIRATION

INTRODUCTION

The student of Mediaeval architecture, especially of the Gothic era,

finds perhaps its strongest appeal in the peculiar structural character

which it possesses. Greek architecture, even at its best, strongly

reflects a preceding art of building in wood. Roman architecture, when

it does not closely follow its Greek prototype, often depends upon a

mere revetment or surface treatment for its effects, and the Renaissance

builders in general followed this lead. Only in the Middle Ages was the

structure truly allowed to furnish its own decoration, and the

decoration itself made structural. And by far the greatest single

problem of construction was that of vaulting. A knowledge of vaulting

is, therefore, essential for the thorough student of Mediaeval

architecture. On the vaulting system depend in a large measure the shape

of piers and buttresses, the size and form of windows and arches, and a

host of decorative mouldings and details which form the complex whole of

Mediaeval construction.

Inheriting from Early Christian times a church of well-established plan,

the builders of the eleventh to the sixteenth centuries set themselves

the problem of substituting for the wooden roof of this Early Christian

Basilica a covering of masonry which would resist the conflagrations

that were among the most destructive forces of the Middle Ages. It is

with these efforts that the following pages are to deal. It has been my

purpose to classify and to discuss in a systematic manner what has been

gathered from authorities here and abroad and from a study of the

monuments themselves.

Especial emphasis has been laid upon the connection between the vaulting

and lighting problem. Some vaults, such as those of six-part and

five-part form, are shown to have probably derived this form from the

clerestory, while other vaults of nave, apse, and ambulatory are proved

to be very closely related to the position of the windows beneath them.

In the discussion of Romanesque vaulting, a number of churches are

suggested as forming a “School of the Loire,” in addition to the schools

which are generally listed. Suggestions are made regarding the form of

the centering employed in Perigord, and there is a somewhat extended

account of the purpose served by the triforia of Auvergne. In dealing

with ribbed vaults the use of caryatid figures for the support of the

ribs, the non-essential character of the wall rib, the origin and

development of six-part vaulting, and the types of chevet vaults are

subjects especially treated. But these and other novelties are all

subordinate to the real purpose of the work, which is to give in a

compact and systematic form a thorough résumé of all the principal forms

of vaulting employed in the middle ages. For the sake of this systematic

treatment the different portions of the church, nave and aisles, choir

and transepts, apse and ambulatory have been taken up in separate

chapters, though in each case there has been an effort to keep as

closely as possible to the chronological sequence of the monuments. This

matter of chronology has, in fact, led to an effort to date as

accurately as possible all the buildings mentioned. For this purpose the

author has consulted many authorities and in the case of doubtful

monuments has arrived at the dates given only after an analysis of the

various claims advanced.

The illustrations are in large measure from photographs taken by the

author or purchased in Europe. The following, however, are from

publications, Figs. 31, 34 and 39 from Gurlitt, _Baukunst in Frankreich_

(J. Bleyl Nacht, Dresden); Fig. 12 from Baum, _Romanische Baukunst in

Frankreich_ (Julius Hoffmann, Stuttgart); Fig. 38, from Bond, _Gothic

Architecture in England_ (Batsford, London), and Fig. 63 from Moore,

_The Mediaeval Church Architecture of England_ (Macmillan, New York).

The drawings are largely based upon plates in Dehio and Von Bezold,

_Kirchliche Baukunst des Abendlandes_ (Cotta, Stuttgart), supplemented

by the author’s own notes. Of course, only a limited number of

illustrations were possible and for this reason less well known

examples, and those not previously published, were in most cases chosen.

To make it possible for the reader to supplement the illustrative

material references are made in the footnotes to publications in which

reproductions of many of the churches mentioned may be found. The books

chosen for reference have, where possible, been those easily accessible

to the student.

The principal literary sources for the work are listed in the

bibliography, though many works not mentioned were also consulted. Among

the sources which proved most useful are the works of Choisy, Enlart,

Lasteyrie, Rivoira, Porter and Moore, all of which are especially

recommended to the student of vaulting. For personal assistance in the

preparation and subsequent reading of the work, the author is much

indebted to Professor Howard Crosby Butler and Professor Frank Jewett

Mather, Jr., of Princeton University, but especially to Professor Allan

Marquand of Princeton, under whose inspiration and encouragement the

work was undertaken.

CLARENCE WARD.

New Brunswick, New Jersey.

October, 1915.

CONTENTS

CHAPTER I. NAVE AND AISLE VAULTS 1

CHAPTER II. TRANSEPT AND CROSSING VAULTS 105

CHAPTER III. APSE VAULTS 124

CHAPTER IV. AMBULATORY VAULTS 158

CHAPTER I

NAVE AND AISLE VAULTS

During the Romanesque period, or roughly speaking, from the beginning of

the eleventh to the middle of the twelfth century, three chief forms of

vaulting were employed over the naves and aisles of church edifices. The

first of these was the dome, the second the tunnel vault, and the third,

groined vaulting. With the development of the ribbed vault, all three

gave way to this new method of construction, and the Gothic era was

inaugurated.

DOMES ON SPHERICAL PENDENTIVES

The dome was employed in two rather distinct ways according to the form

of pendentives used for its support. Thus a number of churches continue

the tradition of the spherical pendentive, while in others some form of

squinch or trumpet arch is found. Both methods are of early origin,

dating back, in fact, to the Roman era preceding the reign of Justinian

(483-565) and consequently earlier than the Byzantine architecture of

which they are so conspicuous a feature. Rivoira[1] has shown the

existence of numerous spherical pendentives of the second century A.D.

or even earlier, and Lasteyrie[2] has added to these a small cupola at

Beurey-Beauguay (Côte-d’Or) in France dating from the second or third

century. But even if this method were known at an early date it was not

until the Byzantine era that it obtained a wide-spread and extensive

usage. During the sixth century it became the principal method of

vaulting throughout the Roman Empire, and, as such, had a considerable

influence upon Carolingian architecture of the ninth and tenth

centuries. This is true even in France, for traces of pendentives were

found in 1870 during a restoration of the church of

Germigny-des-Prés,[3] a fact of particular interest because it is in

France that the principal Romanesque examples of this method are to be

seen.

DOMES ON SQUINCHES

As for the squinch, it may possibly be of Persian origin, but the

earliest examples thus far known in Persia are to be found in the

palaces of Firouz Abad and Sarvistan, which probably date from the

Sassanian period between A.D. 226 and 641, and are therefore of later

date than the Roman examples of the first and second centuries to be

found in the Palace of the Caesars at Rome and the Villa Adriana at

Tivoli (cir. A.D. 138). Whatever its origin, the squinch in its various

forms, simple cross lintel,[4] cross arch, trumpet arch, niche head,

etc., was employed prior to and during the Byzantine period along with

the spherical pendentive. In fact a trumpet arch of domed up character

is found in the Baptistery of the cathedral of Naples[5] which dates

from the fifth century, while the niche head or half dome type, very

commonly employed in Romanesque architecture, has a sixth century

prototype in the church of San Vitale at Ravenna,[6] as well as many

earlier examples such as those in the Domus Augustana (cir. A.D. 83),[7]

or the Thermae of Caracalla (212-216)[8] at Rome. Other types of

squinches occasionally appear but they are generally referable to one of

the above mentioned forms.

THE SCHOOL OF PERIGORD

By far the most important group of Romanesque churches employing the

dome on spherical pendentives, is situated in that portion of France

extending around the city of Périgueux, and constitutes what is known as

the architectural school of Perigord. Since Périgueux was a trading post

on the route from Venice to the west, it must have felt a good deal of

Byzantine influence, and it is the general theory that to this influence

is due the almost universal employment of the dome on pendentives in the

churches of this school. While this may well be the case, it is

nevertheless to be remarked that the dome as a method of vaulting seems

to have been the only importation, its construction in Perigord

differing in almost every particular from that of the Byzantine period.

This might even seem to indicate that the Perigord type of dome was not

imported, but actually indigenous to this part of France, a theory which

has lately been advanced by no less an authority than Lasteyrie.[9] But

in any case, the points of difference in construction between the domes

of Byzantine architecture and those of the school of Perigord are of

more importance in this discussion of vaulting, than is the question of

their origin.

COMPARISON OF PERIGORD AND BYZANTINE DOMES

[Illustration: FIG. 1.--PÉRIGUEUX, CATHEDRAL.]

These differences have been so admirably summed up by Lasteyrie[10] that

a translation of his summary with a few additions will perhaps give the

best possible account of them. They are grouped under six chief heads

which may all be studied by using the cathedral of Saint Front at

Périgueux (Figs. 1 and 2) as a model. First, the French pendentives are

borne on pointed instead of semicircular arches; second, the surface of

the pendentive at Saint Front rises from the intrados rather than from

the extrados of the voussoirs; third, the diagonal profile of the French

pendentive is a complex curve[11] instead of a quarter circle; fourth,

the oldest French pendentives have their masonry in horizontal courses

while the Byzantine frequently have their courses more or less normal to

the curve; fifth the springing of the domes of Saint Front is some

distance back from the circle formed by the pendentives, the diameter of

the dome being thus greater than its impost,[12] while in Byzantine

models, the two correspond; and sixth and last, the domes of Saint Front

are slightly pointed and, for that matter, all the French domes are at

least semicircular, while the Byzantine domes are generally of segmental

section. The explanation of all these differences lies in the material

employed, for the domes of Perigord are of stone, those of Byzantine

architecture are of brick or some other light material. The pointed arch

having less thrust than that of semicircular section was better suited

for stone construction, a fact which explains the pointed section of

many French domes whose outward thrusts were thereby greatly reduced.

Moreover, while the light Byzantine material made possible a dome

without centering constructed after the manner of the Egyptian

“voute-par-tranches,”[13] the heavy stone of the French vault made a

centering absolutely necessary, a fact which explains the setting back

of the dome from the curve of the pendentives so that the ledge thus

formed might serve to support the wooden centering employed.[14] It

explains also the horizontal courses since these allowed a greater

amount of the weight of each course to be borne by the one beneath it,

thus reducing the pressure and making possible a centering of

comparative lightness. But these were not the only results of the

employment of stone. Since the domes of Perigord are much heavier than

the Byzantine domes and exert much more outward thrust it was essential

for them to have very firm supports. Perhaps it is with this in view

that the churches of this school are for the greater part without side

aisles, their outer walls with heavy applied and transverse arches

providing suitable support for the domes. Even when aisles exist, they

are merely deep wall arches forming transverse tunnel vaults rising

from the level of the imposts of the transverse arches of the nave and,

with them, furnishing the support for the triangular pendentives. This

is the arrangement in the cathedral of Saint Front at Périgueux (Fig.

1), the only church in France of this particular type.[15]

THE EXTERIOR ROOFING OF PERIGORD DOMES

One advantage in the employment of the dome of stone lay in the fact

that it might be faced on both the exterior and the interior, or covered

directly by tiles without the use of a bonnet of wood and copper, or a

roof of wood and tile, so frequently seen in Byzantine work. It is

doubtful whether the earliest French domes were treated in this way,

however, for indications would seem to point to the original employment

of a wooden roof over the domes of the cathedral of Saint Front.[16]

Nevertheless, these domes have since been restored with an exterior

stone facing (Fig. 2), and a similar treatment is to be seen at Cahors

cathedral, and over

[Illustration: FIG. 2.--PÉRIGUEUX, CATHEDRAL.]

the crossing of Angoulême. In these domes the drum is first built up in

a slightly ramping wall, to offset the outward thrust of the vault, and

the dome itself is crowned by a lantern toward which it has an upward

curve, rendering the exterior steep enough to shed water readily. At

Angoulême the domes of the nave are entirely concealed by a gable roof,

perhaps in the early manner of the school. Still another type of dome

covering appears at Saint Étienne in Périgueux,[17] where the curve of

the dome does not show on the exterior, but where the drum is first

carried up around the haunch, and then surmounted by a flattened conical

roof of tile, which rests directly upon the vault beneath.

CHARACTERISTICS OF PERIGORD CHURCHES

It has already been noted that the employment of the dome on pendentives

over square bays led to the construction of churches with a broad nave

without side aisles. Among the earliest of these are the church of Saint

Astier (Dordogne), (founded about 1010 but so mutilated as to show

little of its original construction),[18] and Saint Avit-Sénieur

(Dordogne) (cir. 1117), originally with three domes which were replaced

by domed up Anjou vaults in the thirteenth century.[19] The best of the

earlier examples remaining for critical study are, first, the cathedral

of Saint Pierre at Angoulême, whose western bay was constructed between

1100-1125,--the remaining three being but slightly later--and second,

the church of Saint Étienne at Périgueux, originally with four domes,

two of which were destroyed in the religious wars of the sixteenth

century. Of the two which remain the more recent must be earlier than

1163, and the other would seem from its appearance to be about

contemporary with that of the west bay of Angoulême.[20] These two with

the cathedral of Saint Front (after 1120) furnish three excellent

examples of the school, to which a large number of other churches might

be added as illustrating some minor differences in plan or

elevation.[21] The cathedral of Angoulême (Figs. 3 and 4) is

characteristic of the school. Deep wall, and heavy transverse arches

supply substantial impost for the domes. The piers of the western bay

are of simple rectangular plan like those of Saint Avit-Sénieur and

Saint Étienne at Périgueux, while those to the east are of a later

compound type with transverse arches and wall-arches in two orders

instead of the single order of the earlier bay. Except over the

crossing, where there is a high circular drum forming a lantern, the

domes are not pierced with windows around their base. This is due to the

fact that they are covered on the exterior by a wooden roof.[22] It is

more usual to find four small windows at the base of each dome as in

Périgueux, Saint Front (Fig. 1).[23] The use of stone in the

construction of the domes explains the small number of these windows

compared to that in Byzantine architecture,[24] since the stability of

the vault would be threatened by too many openings. Besides this, the

fact that the churches of Perigord have no aisles, properly speaking,

permitted sufficient light to enter through windows in the side walls.

In fact it seems quite possible that the windows in the domes of the

Perigord churches were used to afford resting places for the frame work

of the centering even more than for light, a fact which would also seem

to be true of the four recesses left in the masonry just above the

cornice of the domes of Angoulême cathedral (Fig. 4).

[Illustration: FIG. 3.--ANGOULÊME, CATHEDRAL.]

THE CENTERING OF PERIGORD DOMES

In support of this theory it is possible to point out that if long cross

beams were used in building these domes, it would be difficult if not

impossible to remove them after the dome was finished. If, however, as

at Angoulême, small spaces were left in the masonry it would be possible

to tilt a beam bevelled at each end and resting on the ledge of the dome

and thus remove it without cutting. Still another argument in favor of

this theory is the fact that the open spaces to north and south are

above the level of the ledge, which would seem to indicate that they

were planned to receive the end of a cross beam at right angles to, and

above the one running lengthwise. Of course, when windows took the place

of these small recesses the removal of the beam could be made through

them. There remain, however, a number of churches in which there are

neither windows nor recesses, but in most of these the ledge of the dome

is itself wide enough to support a beam which could be removed without

striking the vault surface.

[Illustration: FIG. 4.--ANGOULÊME, CATHEDRAL.]

As for the choirs of the churches of this school, they were occasionally

domed as at Saint Front[25] (Fig. 1), but were more often covered by a

tunnel vault terminating in the half dome of the apse. The eastern

portion of the choir of Saint Front (Fig. 1) and the choir of Angoulême

(Fig. 4) illustrate this latter arrangement.

NAVES VAULTED WITH DOMES ON SQUINCHES

Although very frequently used over the crossing of Romanesque churches,

the dome on squinches is seldom found over the bays of the nave. There

is in fact no distinct school in which this method is employed and the

examples of its use are widely scattered. The principal one is, perhaps,

the cathedral of Notre Dame at Le Puy (Haute-Loire), which dates from

the eleventh and twelfth centuries. Unlike the domed churches of

Perigord it is of basilical plan with side aisles. The nave is in six

bays with broad arches opening into the aisles and a triforium arcade

above them. Across the nave are transverse arches separating the bays.

The four toward the east are semicircular, the remaining two are pointed

in elevation. These arches rise from imposts nearly or quite as low as

those of the nave arcade, and walls are built upon them to the level of

the string-course above the triforium. Six rectangular bays,--or seven

including the crossing,--of practically square plan are thus formed and

each is covered with a dome. In the western bays,--which are at least a

century later than those at the east end and therefore more advanced in

structure,--a clerestory wall is erected with a single window in its

north and south walls, and openings corresponding to windows from one

bay to the next above the transverse arches, to secure a good

distribution of light (Fig. 5). Across the upper corners of these four

walls and rising from the same level as the window heads, are arches

with half domed triangular niches beneath them, converting the square

into an octagon and furnishing the impost for the domes.[26] These are

octagonal in elevation as well as plan and are laid up in flat panels,

or gores, which meet at the crown (Fig. 6). It is a type of dome

admirably suited to its impost since it presents none of the awkward

appearances of a circular dome on an octagonal base.[27] It is also very

practical from a structural standpoint. Since the gores are flat, the

stone cutting is far less elaborate than in a hemispherical dome, and

the gored dome has the further advantage of great flexibility since it

may be flattened or raised at the crown, placed over a square bay or one

with any number of sides, and made equilateral or with gores of

different widths, all with great facility. Furthermore, when the naves

are of reasonable width, as in most churches with side aisles, the

thrust of the dome is very slight and its downward pressure is not

excessive.

[Illustration: FIG. 5.--LE PUY, CATHEDRAL.]

[Illustration: FIG. 6.--LE PUY, CATHEDRAL.]

But with all its structural advantages, a system like that at Le Puy was

not a satisfactory solution of nave vaulting. The transverse arches were

necessarily so far below the surface of the dome that the continuity of

the nave as a whole was destroyed, and the appearance was rather that

of a series of lantern towers or crossings juxtaposed than of a single

homogeneous vault.

The side aisles of Le Puy are of less importance than the nave, though

the fact that some of their bays were vaulted, or revaulted, at nearly

every period of mediaeval architecture makes them interesting for a

study of consecutive methods. In the bays to the east the vaults are

groined on stilted, round headed transverse arches in the early

Romanesque manner, while the succeeding bays have pointed transverse

arches with groined vaults closely resembling those of the school of

Bourgogne, and the bays nearest the west end have ribbed vaults, in one

case with the early heavy-torus rib, in another with the light rib of

pointed section of a late Gothic rebuilding.

[Illustration: FIG. 7.--POITIERS, SAINT HILAIRE.]

Although not the basis of a school of Romanesque architecture, the

cathedral of Le Puy was not without its influence. This is especially

apparent in the large church of Saint Hilaire at Poitiers (Figs. 7, and

8), which was constructed with very broad nave and aisles,--both

covered with wooden roofs,--after a disastrous fire of 1018, and

dedicated in 1059. In 1130 the vaulting of this church was undertaken,

the result being a most unusual edifice. As the nave was too broad to be

easily covered by a vault of single span, it was subdivided by lofty and

slender piers and arches into a central portion consisting of square

bays,[28] and narrow rectangular bays forming veritable inner aisles on

either side. These narrow bays were covered with groined vaults directly

above the original clerestory windows which thus continued to light the

newly formed nave. Domes were then placed over the square central bays

as had been done at Le Puy, but instead of the niche-head-squinch and

the practically equilateral octagonal dome, small conical trumpet arches

were employed at Saint Hilaire, and the gores of the dome rising from

these were much narrower than the four remaining panels. This gives the

dome rather the character of a cloistered vault with its corners cut off

than of a dome properly speaking. Since the clerestory is below the

level of the transverse arches upon which the domes of Saint Hilaire are

built, the interior has a loftier and less broken appearance than that

of Notre Dame-du-Puy. But even so the effect is not remarkably pleasing.

The side aisles of Saint Hilaire (Fig. 8) are quite as interesting in

their vaulting as the nave. A single broad aisle on either side, which

apparently opened into the nave through lofty arches rising almost to

the clerestory, and which probably had transverse arches with ramping

walls carrying half gable roofs, was altered when it was determined to

vault the church. In doing this, two arches with a solid wall above were

placed under each of the original arches of the nave arcade, a slender

column built up in the center of each of the original bays, and upon the

pseudo-double side aisles thus formed, compound groined vaults were

constructed in a manner best understood from the photograph (Fig. 8).

Except for those just mentioned there are but few Romanesque

churches,--outside of Italy and Sicily,--in which the nave is covered by

a series of domes.[29] But because of the powerful Byzantine influence,

these latter

[Illustration: FIG. 8.--POITIERS, SAINT HILAIRE.]

countries contain a large number of churches of semi-Byzantine,

semi-Romanesque character, some of which are as late as the thirteenth

century.[30] Most of these are so distinctly Byzantine that they do not

properly fall within the province of this book, in spite of their late

date; but others, like the cathedral of Molfetta,[31] have a vaulting

system quite closely allied to the Romanesque.[32] In this particular

cathedral, a nave of three square bays is covered by three domes, one

on flattened spherical pendentives, the others on niche-head-squinches.

Two of them rise from drums and unlike their Byzantine prototypes, they

are all of stone.[33] Moreover, the side aisles are covered with half

tunnel vaults on full transverse arches, the crown of the vaults

together with the nave walls above them acting as admirable buttresses

for the domes. A system not quite so logical exists in the aisles of the

church of San Sabino at Canosa (1100), where there are full tunnel

vaults which do not serve so adequately as buttresses.

PYRAMIDAL VAULTS

[Illustration: FIG. 9.--LOCHES, SAINT OURS.]

Although not vaulted with domes, the church of Saint Ours at Loches in

France (Indre-et-Loire) (Figs. 9 and 10) has a close connection with

such churches as those of Perigord and Notre Dame-du-Puy. This

collegiate church was probably constructed a little before 1168, and

originally consisted of a nave divided into square bays by transverse

arches of pointed

[Illustration: FIG. 10.--LOCHES, SAINT OURS.]

elevation and side aisles which have now disappeared. Each nave bay is

converted from a square into an octagon by flat triangular pendentives

on very small trumpet arches. But instead of domes, the builders of

Saint Ours substituted a hollow octagonal pyramid of stone over each

bay. Such a system, while presenting the same aesthetic objection as

that of Le Puy, had greater structural advantages. The pyramids could be

built entirely without centering, and exerted almost no outward thrust,

while the stones of which they were constructed could be faced on the

exterior (Fig. 9) as well as the interior, and the steep roof thus

formed provided adequate drainage for the rain and snow of the

region.[34]

TUNNEL VAULTS

If the dome played but a small part in Romanesque architecture, such was

not the case with the tunnel vault. Almost as old as civilization

itself, this method of vaulting had been employed to a greater or less

extent in every age from the Egyptian period to that of the Carolingian

Empire. It is natural, therefore, to find it the principal method in use

during the entire Romanesque era. Nor is it necessary to trace its

history back to Persian or Armenian sources. The builders of the

eleventh and subsequent centuries had plenty of examples nearer at hand.

Roman vaults, some of them of stone, were still in a good state of

preservation in many parts of the western world, and almost every

country or province possessed examples dating from Carolingian days.[35]

It is not the use of this roofing system, therefore, but the skill with

which it was adapted to the naves and aisles of churches of basilical

plan, that furnishes the most interesting features in the study of

Romanesque tunnel vaulting. In fact, so distinct are the combinations

and methods employed in different regions, that they constitute

veritable architectural schools which may be classified and separately

discussed.[36]

ROMANESQUE SCHOOLS OF TUNNEL VAULTED CHURCHES

The four major schools lie in France and center around the ancient

provinces of Provence, Poitou, Auvergne, and Bourgogne, whence they

derive their names. All four are comprised in practically the same

period,--namely, the eleventh and part, at least, of the twelfth

centuries,--and it would be impossible to arrange them in any

chronological order. But from its resemblance to the Roman monuments in

the midst of which it grew and the fact that it had comparatively little

structural influence upon the other schools, Provence will be the first

to be considered.

THE SCHOOL OF PROVENCE

The cities of Arles and Nîmes had been important Roman provincial

centers. Moreover, they still retained, and to this day possess, a large

number of Roman monuments whose influence upon the Romanesque churches

of the eleventh and twelfth centuries is plainly apparent. Thus vaults

which carry directly the tiles of the roof, single aisled churches

resembling the little Nymphaeum, or so-called temple of Diana at Nîmes,

the employment of flat pilasters in place of the more usual applied

shafts of curved section, and a host of minor details all reflecting

classic usage are marked characteristics of this school.

PROVENCE CHURCHES OF THE FIRST TYPE

When considered from the point of view of vaulting, the churches of

Provence fall into five distinct groups. The first, illustrated by the

chapel of Saint Gabriel near Tarascon (Bouches-du-Rhône),[37] is

composed of churches with no side aisles. These are covered with tunnel

vaults of semicircular or pointed section, with or without transverse

arches and carrying directly the tiles of the roof. The supporting walls

are frequently strengthened by a series of interior applied arches in

one or more orders thickening the wall at the impost of the vault.

Outside of this interior buttressing, which has already been seen in

Perigord, the churches of this type are of little structural interest.

PROVENCE CHURCHES OF THE SECOND TYPE

In the remaining groups, side aisles are always present and these have

four distinct vaulting systems. In the first, tunnel vaults are employed

throughout the edifice. Saint Nazaire[38] (after 1090), the former

cathedral of Carcassonne (Aude), though somewhat removed from the center

of the school, illustrates this system. Both nave and aisle vaults rise

from the same impost level. The vault of the nave is slightly pointed,

those of the aisles are semicircular, and both have transverse arches.

It is a simple and practical method of construction, since the aisle

vaults furnish admirable abutment for that of the nave, and all three

are covered by a gable roof of masonry resting directly upon the vault

crowns. Its one great fault is the absence of direct light in the nave,

a condition which introduces the problem of lighting a tunnel-vaulted

church.

THE LIGHTING OF TUNNEL-VAULTED CHURCHES

This problem was second only to that of constructing the vaults

themselves and, furthermore, it had much to do with the forms which

these assumed and even with the plan of the church. When there were no

side aisles, windows were cut directly through the outer walls, but to

introduce a clerestory above an aisle arcade involved a number of

structural difficulties. The side aisle vaults no longer aided in

supporting that of the nave, and in fact exerted an inward pressure at a

point below its impost where such pressure was most difficult to offset.

At the same time, the outward thrust of the central tunnel vault was

increased in proportion to its elevation from the ground. The simplest

method of meeting these difficulties was to increase the thickness of

the clerestory walls, or add simple salient buttresses and trust to good

construction to offset the increased thrusts. This was the method

adopted by most of the Romanesque builders.[39] It was only in the

school of Bourgogne, and under its influence, that the problem received

a better solution--which will later be discussed at length--and not

until the Transitional and Gothic periods that it was completely solved

by dispensing entirely with the tunnel vaults.

While its chief effect was upon vaulting, the lighting problems

frequently affected the plan of the church as well. When the nave was

without direct light, the aisles were almost always narrowed to permit

light to enter from windows in their outer wall. Double aisles were

practically impossible,[40] unless the inner aisles had triforium

galleries supplied with windows.[41]

Nor did the problem of lighting enter merely into the construction of

simple tunnel vaulted churches. It was involved with that of all kinds

of vaulting throughout the entire Romanesque and Gothic periods.

Transverse tunnel vaults like those of Tournus, groined vaults like

those of Vézelay, the development of the Gothic chevet from the half

domed apse, and the systems of ribbed vaulting which are frequently

found in the crossings, aisles, and ambulatories of Gothic churches, all

are closely related to the lighting problem.

PROVENCE CHURCHES OF THE SECOND TYPE CONTINUED

Returning to Provence, it will be recalled that Saint Nazaire at

Carcassonne was described as a typical example of the second class of

churches of this school, entirely tunnel vaulted, with narrow side

aisles whose lateral windows afford the only light with which the nave

is supplied. There are, however, a few churches, vaulted like Saint

Nazaire, in which the builders introduced a clerestory. Among these is

the abbey church of Saint Guilhem-du-Désert (Hérault) (rebuilt at the

end of the eleventh century).[42] Here the clerestory is of considerable

height, the heads of the windows lying beneath the imposts of the tunnel

vaults, a fact which renders this church one of the most developed of

the school. Yet this development lies merely in the presence of the

windows, and not in any structural advances which made their presence

possible. It was because of the excellent masonry of the heavy walls and

piers, that the Provence builders dared to attempt this innovation. The

vaults themselves are no lighter than before and still carry the entire

weight of the roof. In fact, the whole system is one of inert stability,

analogous to Roman construction, and exhibits little if any advance

toward the elasticity and balanced thrusts which were to characterize

Gothic architecture.

PROVENCE CHURCHES OF THE THIRD TYPE

The churches in the third Provence group differ from those in the second

only in having half tunnel vaults in the side aisles, but this

difference is sufficient to change to some extent the character and

methods of construction. In the simple churches of this type where there

is no clerestory as, for example, in the western portion of the little

church of Saint Honorat, belonging to the monastery of the

Isle-de-Lérins (Alpes-Maritimes),[43] the half tunnel vault of the

aisles furnishes better abutment for that of the nave than the full

tunnel vaults of the second type, and at the same time permits loftier

arches to be constructed in the nave arcades, giving a better

distribution of light without raising the imposts of any of the vaults.

When, however, a clerestory is added, as in Saint Trophime at Arles

(first half of the twelfth century), the inward pressure of the aisle

vaults is even more severe than in Saint Guilhem-du-Désert and at the

same awkward place, so that the only structural advantage at Arles lies

in the added height of the nave arches. It is a noticeable feature of

Saint Trophime that the aisles have full, instead of half arches[44]

used transversely beneath the vaults, very probably because the former

exerted less inward thrust, and could also be weighed down by a solid

wall which increased the rigidity of the structure by tying the pier of

the nave arcade to the outer wall, and strengthened the clerestory for

the support of the high vault. The system has already been noted in the

cathedral of Molfetta,[45] and will be found repeated either in the

triforia or aisles of a number of Romanesque churches of different

schools.[46]

PROVENCE CHURCHES OF THE FOURTH TYPE

The employment of a three-quarters tunnel vault over the aisles renders

the fourth group of Provence churches a cross between the second and

third. Like them it contains examples with and without a clerestory. Of

these the cathedral at Vaison (Vaucluse)[47] (twelfth century)

illustrates the former, and the abbey church of Silvacane

(Bouches-du-Rhône) (second half of the twelfth century)[48] the latter

form. The advantage of the three-quarter type lies in the fact that it

exerts less thrust against the inner wall than does the half tunnel and

still makes possible loftier arches in the nave arcade compared to the

height of the aisle vault than does the full tunnel vault. But these

slight advantages are offset by its ugly appearance, and it was never in

any sense popular.

PROVENCE CHURCHES OF THE FIFTH TYPE

The system of the fifth type of the school of Provence is that of a

tunnel vaulted nave with side aisles covered by transverse tunnel

vaults. This method is, however, so different from the other four and

was so widely extended,--largely through Cistercian influence--that it

can hardly be said to be inherent in any one school, but rather to

constitute an individual group of churches which will be separately

considered.

From the foregoing discussion of the entire school, it will be seen that

the builders of Provence produced very little that was original in vault

construction. It was not a school of progress, but rather one of

conservative adherence to the Roman tradition of the province around

which it centered. Its most progressive feature was, perhaps, the

preference it displayed for the pointed tunnel vault,[49] and this may

be explained by the fact that the vault in Provence generally carries

directly the tiles of the roof and less masonry was necessary to carry a

pointed vault up into a gable than would have been the case with one of

semicircular section. One further preference, which shows the structural

sense of the Provence builders, is that for transverse arches under the

vaults, which not only make possible lighter masonry in the vaults

themselves, but also lessen the centering necessary for their

construction.

VAULTS SIMILAR TO THOSE OF PROVENCE IN OTHER ROMANESQUE CHURCHES

Such methods of vaulting as those just described are not confined to

Provence. In Poitou, for example, there is a group of churches with

half-tunnel vaults in their side aisles. Some of these, like Saint

Eutrope at Saintes (Charente-Inférieure)[50] (eleventh century) and

Aigues-Vives (Loir-et-Cher),[51] have corresponding half arches,

others, like Parthenay-le-Vieux (Deux-Sèvres),[52] (cir. 1129) have full

transverse arches beneath these vaults. Moreover, in Auvergne the

triforium is regularly covered with a half tunnel vault buttressing the

tunnel vault of the nave, and in a few instances, as at Culhat

(Puy-de-Dôme),[53] the side aisles are in one story with similar

vaulting. There are also many instances outside of Provence in which the

aisles have full tunnel vaults. Between Auvergne and Bourgogne there is

an example in the abbey church at Souvigny (Allier) (eleventh century)

(Fig. 11), and such a system may quite possibly have been employed in

the aisles of Cluny[54] and in those of the choir of Saint

Benoît-sur-Loire (Loiret)[55] (second half of the eleventh century).

Even in England it occurs in the Tower Chapel at London[56] (begun

1078), and is also found in Poitou at Melle (Deux-Sèvres), Saint

Pierre[57] (early twelfth century), where the vaults are pointed, and at

Lesterps (Charente),[58] where they are of semicircular section. The

three-quarter tunnel vault also is not confined to Provence for it

appears as far north as Saint Genou (Indre) in the eleventh century.

The foregoing examples serve only to indicate that such systems as these

which are inherently simple in construction came, very naturally, to be

widely employed during the Romanesque era. Where they originated it is

impossible to say, but the fact that they are so elementary in principle

and often vary in some of their structural characteristics[59] may

indicate that they were developed independently and contemporaneously in

various localities.

NAVES WITH TUNNEL VAULTS AND AISLES GROINED

The next three schools of Romanesque architecture have one feature in

common, namely, the employment of groined vaults over the side aisles.

But the form which these assume and their relations to the tunnel vaults

of the nave differ sufficiently to distinguish the churches of Poitou,

Auvergne and Bourgogne from one another.

[Illustration: FIG. 11.--SOUVIGNY, ABBEY CHURCH.]

THE SCHOOL OF POITOU

The chronology of the churches of Poitou is somewhat obscure, but the

vaulting principles of the school were well developed early in the

eleventh century, to which period a number of the existing churches

belong. Their naves are tunnel vaulted and without a clerestory, the

light entering through windows in the outer walls of the aisles, which

are narrow and high and covered with groined vaults rising from the

imposts of the arches opening into the nave. The entire church has a

single-gabled exterior roof of wood and tile, its rafters supported near

their centers by a wall above the nave arcade, and thus not resting

directly upon the extrades of the vaults.[60] Certain minor structural

differences make it possible to divide the churches of Poitou into two

groups.

The first is composed of the earlier churches, of which Saint

Savin-sur-Gartempe (Vienne) (begun cir. 1023) is the best and perhaps

the only existing example. In it, both nave and aisle vaults are without

transverse arches. All the vaults are semicircular in section, and those

of the aisles[61] have their transverse surfaces continuous with the

soffits of the nave arches.[62] This gives them the flattened groins so

characteristic of Roman architecture. Such a system as this required an

extensive wooden centering, and it is not surprising that the builders

of Poitou soon introduced transverse arches beneath the vaults,--perhaps

through the influence of Lombardy, where they were in use as early as

the tenth century[63]--thus producing a group of churches which form the

second type of the school.

Notre Dame-la-Grande at Poitiers (Vienne) (early twelfth century), is an

early example of this class. Transverse arches are employed throughout

the church, not only strengthening the vaults but making it possible to

save centering by using the same form for each successive bay and at the

same time reducing to some extent the thickness of the web by thus

breaking it up into smaller units.[64]

Toward the second half of the twelfth century the system was still

further improved by the introduction of pointed arches and vaults in

both nave and aisles, as for example in the abbey church of Cunault

(Maine-et-Loire). The flattened type of groin has here been abandoned,

though the vaults are not of domed-up type. Such doming is to be found

in Poitou, however, in Saint Pierre at Chauvigny (Vienne),[65] probably

with the intention of saving centering, as in Byzantine architecture.

But even though the builders of Poitou made some progress in vaulting,

they never attempted to solve the associated problem of getting direct

light in the nave. Hence such progress was but slight from the earliest

to the latest churches of the school.[66]

THE SCHOOL OF AUVERGNE

THE ORIGIN AND USE OF THE TRIFORIUM GALLERY IN AUVERGNE

One of the distinguishing features of the typical churches of Auvergne

is the presence of a second story or triforium gallery above the side

aisles. To account for its presence a number of theories have been

advanced. That such galleries were not intended for congregational

purposes, at least in the early churches of the school, is evident from

the fact that they are but dimly lighted and accessible only by narrow

staircases in dark corners. They may have been used for storerooms or

treasuries for relics brought by pilgrims,--a possibility which is

strengthened by the fact that they ceased to be built in the thirteenth

century when the era of the Crusades was past,[67]--or they may have

been useful places from which to defend the church, corresponding in

this respect to the room frequently found in the second story of

Romanesque towers.[68] But whatever their use, they would seem, in

Auvergne, at least, to have originated on purely structural grounds.

The expedient of dividing the openings from the nave of the church to

the aisles into two stages, with the evident intention of thus reducing

the height of the piers and even of making lighter piers possible, was

employed in a number of churches both earlier and later than those in

Auvergne. It may even be in part the explanation of the double colonnade

in the Lateran Baptistery, and the upper stories in the chapel at

Aachen, and the abbey churches at Essen, Nymwegen, and elsewhere. In any

case, it explains the system of two stories of arches in the Carolingian

church of Saint Michael at Fulda (818-822),[69] and in the early

Romanesque churches of Vignory (Haute-Marne)[70] (eleventh century),

Montiérender, (Haute-Marne)[71] (early eleventh century), and

Chatel-Montagne (Allier)[72] (early twelfth century), and probably also

in Saint Pierre at Jumièges (Seine-Inférieure)[73] (cir. 940).[74]

A significant fact in connecting these churches which are wooden roofed,

with the vaulted churches of Auvergne, lies in their geographical

distribution. While the earliest examples such as Fulda lie in the

Carolingian region, the latter examples, Jumièges, Vignory and

Montiérender lie but slightly north of Auvergne, while Chatel-Montagne

is actually in this province.[75] What is more natural to suppose, then,

than that the vaulted churches of Auvergne were based upon these earlier

churches, and that the nave arcade in two stages was retained even when

both aisles and nave were covered with vaults? Furthermore, it would

then be perfectly natural that the builders should have built these

vaults in two stories corresponding to the two stages of arches, since

they would have promptly recognized the great advantage gained by this

system, which stiffened the interior and exterior walls for the added

weight which the high vaults brought to bear upon them, without injuring

to any extent the appearance of the church.[76] This seems all the more

plausible when the fact is considered that the churches of Auvergne

generally have broader aisles than those of Poitou or Provence. This may

also have been a heritage from the early churches with two-storied

arcades and wooden roofs just mentioned,[77] and in any case it further

explains the system of aisle vaults in two stories. For, while the

vaults of narrow aisles might be raised a considerable distance from the

ground without danger from excessive thrusts, in wide aisles they would

have exerted such thrusts and pressures on piers and walls as to have

rendered their support most difficult, particularly when they carried

directly the tiles of the roof as in Auvergne.

THE SCHOOL OF AUVERGNE CONTINUED

As to the actual vaulting system of the Auvergnate churches, it is as

follows. In the nave, heavy tunnel vaults resembling those of Provence

in that they usually carried the roof.[78] Otherwise the churches are

more like those of Poitou in the form of the piers, the almost universal

absence of a clerestory, and the employment of vaults of semicircular

section with transverse arches, as in the early churches of the second

class in that school. In the triforium, the builders realized the

advantage gained by the use of a half tunnel vault as an offset to the

nave thrusts and as a means of best filling the space beneath a single

gable roof,[79] and this is therefore the universal method. At times

this vault is borne on full semicircular transverse arches,[80] and at

others on those which follow its curve.[81] In the side aisles, groined

vaults were employed because they were the only kind which could be

built without cutting into either the triforium or the side wall

windows. In form they closely resemble those of Poitou and were provided

with transverse arches.

CHURCHES OF THE AUVERGNE SCHOOL

The church of Notre Dame-du-Port at Clermont-Ferrand (Puy-de-Dôme)[82]

(Fig. 12) (cir. 1100) has the Auvergnate characteristics just described.

Its great fault lies in the darkness of the interior, a darkness more

pronounced than that of the churches of Provence or Poitou because of

the width and lowness of the aisles with the consequent distance of the

lateral windows from the nave and the fact that they cannot be cut very

high above the floor. The windows of the triforium are also small,[83]

and their light is almost entirely confined to the gallery by its floor

and by the smallness of the arches opening into the nave. This fault was

remedied in the choir, where the light was most needed, by doing away

with the triforium, and placing a clerestory beneath the half dome of

the apse.[84] As a further improvement a lantern was placed over the

crossing.[85]

[Illustration: FIG. 12.--CLERMONT-FERRAND, NOTRE DAME-DU-PORT.]

In certain churches of the school like Saint Sernin at Toulouse (nave

twelfth century), the triforium was increased in size, perhaps in order

that it might be used for congregational purposes, but more probably

because larger windows were absolutely necessary in this portion of the

church for the sake of the lighting. This theory is strengthened by the

fact that Saint Sernin has double side aisles and the lateral windows

are therefore too far away to light the nave. These added aisles are

covered with vaults of regular Auvergnate character, even to the extent

of half tunnel vaults beneath their roofs, and the remainder of the

church corresponds to the structural standards of the school.[86]

CHURCHES OF AUVERGNE WITH A CLERESTORY

Although it might seem from the foregoing pages that the builders of

Auvergne were very backward in structural technique, there are a number

of churches in the school which have a clerestory in the nave. Among

them is Saint Étienne at Nevers (Nièvre)[87] (end of the eleventh

century),[88] in which the clerestory is obtained by raising the wall

above the triforium arches just high enough to permit the introduction

of comparatively small windows with their heads rising above the impost

of the vaults.[89] The principle is the same as that in Provence, and no

structural innovation is involved. The builders merely relied upon heavy

piers and walls and salient buttresses to bear the added thrust which

the tunnel vaults, thus raised, produced. That their reliance was not

especially well founded is proved by the numerous cracks in the masonry.

THE SCHOOL OF THE LOIRE

The introduction of a clerestory in tunnel-vaulted churches was not yet

scientifically accomplished, and it remained for the school of Bourgogne

to find the best possible solution of the problem. But this solution

would seem to have been reached only after some intermediate steps had

been taken which may, perhaps, be traced in a number of eleventh century

churches. Two of these lie slightly to the north of Poitou and Auvergne

and strongly reflect the influence of these neighboring schools. These

churches, together with others in the same general region, may perhaps

be said to constitute a school of Romanesque architecture, which might

properly be termed the School of the Loire.

The first of these is the small church of Saint Genou (Indre).[90] It is

a combination of the types of Auvergne and Poitou except that the tunnel

vault of its choir is raised on a clerestory wall pierced with good

sized windows. Its aisles are in only one story, and, instead of being

groined, are covered by three-quarter tunnel vaults perhaps showing the

influence of such Provence churches as those of Silvacane and Vaison.

The whole system shows an advance in structural skill in several

particulars. In the first place the aisles are built low, and with

columnar piers close together, thus insuring the support of a heavy

triforium wall. This wall is lightened in appearance but not

structurally weakened, by a wall arcade opposite the vaults and roofs of

the aisles, and is sufficiently thick at the clerestory level to be

pierced with window openings and still afford an excellent impost for

the tunnel vault. This, in turn, is built of light material like the

vaults of Poitou. With exterior salient buttresses, the system is

complete. Its only important drawbacks are the closeness of the

supporting piers and the necessity of keeping the whole choir rather low

to avoid excessive thrusts.

The second church lies between Saint Genou and the school of Bourgogne.

It is the abbey church of Saint Benoît-sur-Loire (Loiret), begun in 1062

and possessing a choir, transepts, and porch, dating from the second

half of the eleventh century. Its choir (Fig. 13) closely resembles that

of Saint Genou in every particular, except that the aisles have full

tunnel vaults and the church as a whole is larger with a much more lofty

nave of greater span.[91] Such a system as that of Saint Genou and Saint

Benoît is produced by the extension of the elevation so frequently seen

in the apses of the churches of Poitou and Auvergne to embrace the sides

of the choir as well. The columnar piers and small arches used are like

those in the apse rather than like those in the remainder of the church.

The builders seem, however, to have failed to realize that walls which

would support the half dome of the apse would not necessarily prove

sufficiently strong to resist the thrusts of a tunnel vault. In fact, in

spite of its apparent advance, the vault of the choir of Saint Benoît

was only prevented from falling by the addition of transverse arches

and flying-buttresses at a date subsequent to the completion of the

church, and the vault of the nave of Cluny, which was quite possibly

similar, actually fell in 1125.[92] It remained for the twelfth century

builders of Bourgogne to take the final steps which were to carry the

system of tunnel vaulted naves with direct light to its highest

development.

[Illustration: FIG. 13.--SAINT BENOÎT-SUR-LOIRE, ABBEY CHURCH.]

THE SCHOOL OF BOURGOGNE

It is most unfortunate for a study of the school of Bourgogne that the

mother church at Cluny (Saône-et-Loire) should have been almost totally

destroyed in the French Revolution. This great church was begun in 1089

and must have been finished in 1125, for the nave vaults fell in that

year and were rebuilt before the final consecration in IIVO. What its

original vaulting system was is difficult to say. Reber[93] says that it

was probably vaulted like the churches of Auvergne with inner aisles in

two stories, but Rivoira[94] states that both the nave and aisles had

tunnel vaults on transverse pointed arches. The exterior view,[95] and

the model which fortunately remains, would correspond with either

arrangement.[96] The important facts to note are that the nave had a

clerestory, and that the nave vault was strengthened on the exterior by

carrying up the clerestory walls to exert a downward pressure at its

haunch, a most important structural advance over the exterior wall of

Saint Benoît-sur-Loire.[97]

[Illustration: FIG. 14.--PARAY-LE-MONIAL, ABBEY CHURCH.]

The developed system of Bourgogne may be seen to advantage in the abbey

church of Paray-le-Monial (Saône-et-Loire) (Figs. 14, 15), which dates

from the early twelfth century and is thus only slightly later than

Cluny itself. Its nave is wider and loftier than any yet seen in which a

tunnel vault was used, though not equal in size to that at Cluny, which

was thirty-two feet wide and ninety-eight feet high. All the structural

arches are pointed, but those used for windows, doors and decoration are

still round headed.[98] The clerestory, while it has only moderately

large windows, is so high above the ground as to render the support of

the vaults above it exceptionally difficult. This difficulty was

overcome, first by giving the vault a pointed section and thus reducing

the thrust; second, by building as light a web as possible and covering

it with a wooden roof; third, by using tie-rods of wood or metal,

running along near the impost of the vault in the thickness of the

walls, thus to a certain extent concentrating the pressure upon the

piers; and, finally, as has already been stated, by carrying the

exterior walls of the church to a point considerably above the window

heads (Fig. 15), thus obtaining a downward pressure which offsets the

outward thrusts.

[Illustration: FIG. 15.--PARAY-LE-MONIAL, ABBEY CHURCH.]

The side aisles of the school of Bourgogne are also worthy of mention.

They are usually covered with groined vaults, in many cases of slightly

domical form. Whether this method came directly from Lombardy where

there exist early examples of its use, or whether it came in through the

influence of Poitou and Auvergne which had come into close contact with

Carolingian architecture, is an open question. It seems quite likely,

however, that, since the Byzantine builders developed this type and

transmitted it to the Carolingian builders of the Rhine valley, it

should have passed from there into France and spread over the three

northern-central schools as it did over Lombardy. Regardless of its

origin, it became the standard type in all the important churches of the

Cluniac region. Occasionally, as at Souvigny (Allier) (possibly eleventh

century), the enclosing arches are of stilted round headed form, a type

which is also found as far north as Vézelay (Yonne) La Madeleine (after

1140) (Fig. 16). Neither of these churches, however, is near the center

of the school,[99] and the pointed structural arch as used in the abbey

church of Paray-le-Monial (Fig. 14) is the common form.

The system employed in Bourgogne marks the highest development attained

in the use of a tunnel vault running the length of the nave. In the

Ile-de-France a few instances might be cited[100] in which a system like

one of those already described was used, and the same is true of certain

Romanesque churches outside of France, but in none of them is any new

structural method introduced. The tunnel vault was even used

occasionally as late as the thirteenth century,[101] but the examples

are generally small and insignificant.

CHURCHES WITH TRANSVERSE TUNNEL VAULTS OVER THE NAVE

Besides the methods which have just been described and which were so

localized as to form veritable Romanesque schools, there remain a number

of churches falling into two groups in which transverse tunnel vaults

replace those running longitudinally either in the nave or aisles. The

first and smaller group contains those in which such vaults were used

over the nave. Of these, the most important example is Saint Philibert

at Tournus

[Illustration: FIG. 16.--VÉZELAY, LA MADELEINE.]

(Saône-et-Loire),[102] a church of considerable size and of early date

(dedicated 1019). Cylindrical piers and transverse arches divide the

nave into rectangular bays each of which is covered by a transverse

tunnel vault with a window in the clerestory wall at either end.

Excellent light is thus obtained and the thrusts of the vaults admirably

counteract one another. In fact, the system is so logical that it is

surprising that it gave rise to so few imitators.[103] The explanation

may perhaps lie in the lack of apparent continuity in the vault, a fault

which this method shares with that of Le Puy. As to its origin, it may

go back to such Persian monuments as Tag-Eivan, or to Syrian copies of

Sassanian work with the substitution of stone for brick as Choisy

suggests,[104] though it is not unreasonable to think that the builders

of Tournus originated the system since it involved no unknown structural

principles. The aisles of Saint Philibert furnish one of the rather rare

examples of the employment of interpenetrating vaults.[105]

CHURCHES WITH TRANSVERSE TUNNEL VAULTS OVER THE AISLES

The second group is much larger and more widespread, and comprises all

the churches employing transverse tunnel vaults over the side aisles.

The examples belonging to the school of Perigord have already been

discussed,[106] and mention has been made of the fact that there are

possibly enough of such churches in Provence alone to constitute a fifth

type in that school.[107] But the system is too widespread to be

attributed to any one province. It is undoubtedly a product of Roman and

very early mediaeval architecture, for it is to be seen in such

buildings as the Basilica of Maxentius at Rome, and in a modified,

ramping form at Aachen.[108] Its structural advantage lies in the large

space which the tunnel vault affords for windows in the outer wall thus

lighting both the nave and aisles. Among the many examples are the

parish church of Chatillon-sur-Seine (Côte-d’Or)[109] of the twelfth

century, the abbey churches of Hauterive (Savoie), Ronceray[110]

(vaulted in 1115), Bénévent-l’Abbaye (Creuse),[111] and the cathedral of

Lescar (Basses-Pyrénées),--in which, however, the vaults are an addition

to a primitive construction.[112] In the church at Fontenay

(Côte-d’Or)[113] (before the middle of the twelfth century) concealed

flying buttresses appear over the transverse arches between the aisle

bays, thus aiding in securing a more even abutment for the continuous

thrust of the tunnel vault of the nave. A few churches like

Cavaillon,[114] and the cathedral of Orange (Vaucluse),[115] have

tunnel vaults over rectangular bays flanking the nave but not connected

by arches to form side aisles.

The vaulting of the ambulatory gallery of Mantes cathedral, of the

aisles of Fountains Abbey in England, and possibly the original vaults

of the aisles of Saint Remi at Reims[116] were also transverse tunnel

vaults. These latter churches differ from the ones previously mentioned,

however, in that they are not tunnel vaulted in the nave and, moreover,

are constructed with a clerestory so that the side aisle vaults do not

serve the purpose outlined in the account of tunnel vaulted churches in

the preceding paragraph.

TUNNEL VAULTS WITH CROSS RIBS

This brings the discussion of the standard methods of tunnel vaulting to

a close, but there remain two curious churches in which cross-ribs were

added beneath the surface of simple tunnel vaults. One of these is at

Lusignan (Vienne),[117] and the other at Javarzay (Deux-Sèvres). Both

date from about 1120 to 1140 though the ribs may be a later addition to

give the appearance of ribbed vaulting which was introduced at about

this time.

NAVES WITH GROINED VAULTS

Although usually confined to the side aisle bays, there are a few

Romanesque churches in which the builders of the eleventh and twelfth

centuries placed groined vaulting over the nave. The scarcity of such

examples is due primarily to the difficulty of meeting the severe

outward thrusts of a groined vault raised over bays of considerable span

and at a point high above the ground. In the side aisles where the

vaults were comparatively low, the exterior wall could be thickened by

salient buttresses, and the piers strengthened by the weight of the wall

above in a manner to offset the thrust, but in the nave the problem was

more complicated. The builders had not yet invented the flying buttress.

Hence, when they attempted groined vaults at all, they blundered along

trusting that the inert mass of their walls and such timid buttresses as

could be erected above the nave piers would provide sufficient offset

for the thrusts even though these were now concentrated at four main

points in each bay. Naturally the vaults frequently gave way and had to

be reconstructed. In spite of these difficulties, the advantage of the

groined vault in providing a clerestory whose windows might rise as high

as the crown of the vault itself led to its occasional use.

GROINED VAULTS OVER RECTANGULAR NAVE BAYS

The vaults thus employed were of two rather distinct classes, those over

rectangular nave bays which were usually but little domed up, and those

over square bays which were generally distinctly domed in the Byzantine

manner. Of the first type perhaps the best known example is the

Burgundian church of La Madeleine at Vézelay (Yonne), (Fig. 17)

dedicated

[Illustration: FIG. 17.--VÉZELAY, LA MADELEINE.]

in 1104. Its nave is divided into a series of rectangular bays by

transverse arches of semicircular section, and over each bay is placed a

groined vault very slightly domed at the crown. To insure the stability

of these vaults, the builders relied on the weight of the walls, which

were carried up somewhat above the window heads, and on simple salient

buttresses. To these exterior supports were added interior arches half

imbedded in the walls above the clerestory windows (Fig. 17), furnishing

one of the earliest examples of the use of wall ribs or formerets. The

web of the vault does not, however, follow their extrados, but gradually

breaks away from it toward the crown, with the apparent object of thus

concentrating even more pressure upon the piers by stilting the wall

line of the vault surface.[118] Even these precautions were not deemed

sufficient, so iron tie-rods were employed, but these rusted and

broke,[119] the vaults settled badly,[120] and if it had not been for

the addition of exterior flying buttresses, which had meanwhile come

into general use, the vaults would most certainly have fallen. Although

not a structural success, Vézelay did prove of advantage in turning the

builders away from the tunnel vault,--and this, too, in Bourgogne where

it had been most highly developed,--to a new type which presented

problems whose solution was to lead to Gothic architecture. Vézelay was,

however, but little imitated in the Romanesque era, perhaps because of

the almost contemporary development of the ribbed vault in Lombardy,

Normandy, and the Ile-de-France. A few churches, such as Anzy-le-Duc

(Saône-et-Loire)[121] did employ groined vaults over the nave but on a

smaller scale and frequently with more pronounced doming.

A more important and independent group of groined vaulted churches is to

be found in Normandy. In this school, the churches were usually covered

with wooden roofs though the aisles were occasionally groined. But there

are three churches in which the choir also has groined vaults. These

are, La Trinité or the Abbaye-aux-Dames at Caen (Calvados) (cir. 1066),

Saint Nicolas at Caen (cir. 1080), and Saint Georges-de-Boscherville at

Saint Martin-de-Boscherville (Seine-Inférieure) (late eleventh and early

twelfth century). The choir of the third of these churches, though later

in date than the others, is more primitive in type, for it is covered by

interpenetrating vaults, in which, however, the deep lunettes above the

windows rise so nearly to the crown that the result resembles groined

rather than tunnel vaulting.

In both the other examples true groined vaulting is used, but at La

Trinité it is in practically square bays, and carried by walls running

down to the ground,[122] making it easier of construction than that at

Saint Nicolas[123] where the bays are rectangular and the choir has true

side aisles. This church is similar in structural principles to La

Madeleine at Vézelay--except that the wall ribs are omitted,--and these

two churches may be said to represent the highest point reached by

groined vaulting with practically flat crowns during the Romanesque

period.

Other examples might be cited, ranging from such an unusual church as

Saint Loup-de-Naud (Seine-et-Marne) in the Ile-de-France,--which is of

uncertain date,[124]--to churches as late as the thirteenth and

fourteenth centuries, among which are Severac-le-Château (Aveyron) and

Saint Pons-de-Mauchiens (Hérault).[125] Occasionally, also, groined

vaults were used in the crypt as at Saintes (Charente-Inférieure),[126]

even when tunnel vaults were used in the upper part of the church, a

peculiarity explained by the fact that underground it was easy to

dispose of the thrusts which could not so readily be offset in the nave.

The question of the origin of the method has frequently arisen and a

number of writers, including Choisy,[127] suggest the East as a possible

cradle of the style because of the numerous churches in Palestine thus

vaulted, but Rivoira[128] shows rather conclusively that it was the

Cluny influence which carried the method to the East rather than the

reverse, a theory strengthened by the fact that the earliest example

there, which is the church of Saint Anne at Jerusalem,[129] would seem

to be after rather than before the beginning of the twelfth

century.[130] Moreover it is quite reasonable to attribute the

development of this advanced type of vault to the builders of Bourgogne

themselves, for they were surely progressive enough to have taken such a

step.

GROINED VAULTS OVER SQUARE NAVE BAYS

Churches with groined vaults over square nave bays are much more

numerous than those with rectangular bays, just described. The most

important of these belong to the school of the Rhenish Provinces, which

had, perhaps, clung to Byzantine and Carolingian traditions in this

respect. As a rule the large churches of this school were originally

planned for vaulting only in the side aisles.[131] These were usually

divided into square bays by round headed transverse arches, and then

each bay covered by a more or less domed up groined vault, which, from

its size and form, might be erected with comparatively little

centering.[132] There was no triforium gallery, but a wall with blank

arches took its place beneath the clerestory windows. In many of the

churches[133] shafts were carried up on the inner face of alternate nave

piers, probably to support the cross beams of the roof, or possibly to

carry transverse arches, but not to carry vaulting.

By the early twelfth century, after numerous fires had played havoc with

the churches, the Rhenish builders seem to have at last made an effort

to replace the wooden roofs with vaults. In doing this, they sought a

form of vault which would exert as little as possible of outward thrust

and thus be stable at the considerable height at which it must be

placed. The Lombard builders had by this time developed the domed up

cross-ribbed vault, but, as has been admirably shown by Porter,[134] the

ribs which they employed had for their sole purpose the saving of wooden

centering, since the masonry of the vault proper was heavy enough to

stand without their aid. It was natural then for the Rhenish builders,

who copied their neighbors in Lombardy in many particulars,[135] to look

to them for a method of vault construction, which they found in domed up

vaults like those of Rivolta-d’Adda (1088-1099) or Sant’Ambrogio at

Milan (cir. 1098). These the Rhenish builders chose as models, but

being plentifully supplied with wood for centering, it would seem as if

they purposely did not adopt the diagonal ribs, but built groined vaults

of simple domed up type, placing them over square nave bays each

corresponding to two aisle bays in the true Lombard manner. This system

may be seen to advantage in the cathedral of Speyer[136] (probably

vaulted cir. 1137-1140). With extremely heavy walls like those of the

Rhenish churches, and with good masonry for their construction, such

vaults proved comparatively safe even over naves of such a span as that

of Speyer which is almost fifty feet in width.

This account of the Rhenish school completes the discussion of groined

vaulting as applied to the naves and choirs of Romanesque churches. The

heavy walls and the general excellence of masonry construction which

they required, together with the necessity for large interior piers, did

not render them popular or widely used.

AISLES WITH GROINED VAULTS IN LOMBARDY AND NORMANDY

That the use of groined vaults was far more extensive in the aisles than

in the naves of Romanesque churches has already been shown by the

examples cited from the schools of Poitou, Auvergne, Bourgogne, and

elsewhere. To these should be added a number of churches, chiefly of the

schools of Lombardy and Normandy, which have groined aisles in

combination with rib vaulted or wooden roofed naves. In Lombardy, where

the naves are ribbed, this combination has been admirably explained by

Porter[137] in connection with the use of wood for centering. Thus he

shows that groined vaults, provided that they were sufficiently domed

up, could be built over the small bays of the aisles and triforia with

almost no wooden framework, but that when such vaults were attempted in

the nave the bays were so large as to require a considerable amount of

centering beneath the vault, and therefore the builders substituted

permanent diagonal arches of very heavy character.

The Norman groined aisles are, however, of a different sort, for they

either have level crowns or are but slightly domed up in type.[138] The

abbey church of Jumièges (Seine-Inférieure) (1040-1067) is among the

earliest examples of this construction and is the only Norman church

with groined vaults in both the aisles and triforium.[139] La Trinité at

Caen[140] and the abbey church of Lessay (Manche)[141] are also Norman

churches with groined aisles, in both cases with level crowns. In La

Trinité, as in the early churches of Poitou, the bays are not even

separated by transverse arches.[142] In Saint Étienne at Caen, and in

the choir of the cathedral of Gloucester, the aisles are vaulted in both

stories like those of Auvergne, the lower groined, the triforia with

half tunnel vaults, but it seems very probable that these latter were

added only when vaulting took the place of the wooden roof in the

central portions of the church.[143]

Curious instances of the persistence of groined vaulting are to be seen

in the triforia of such transitional churches as Saint Germer-de-Fly

(Oise)[144] and Vézelay, where the remaining portions of the church have

ribbed vaults. For this persistence an explanation is later

attempted.[145]

AISLES WITH SEMI-GROINED VAULTS

An unusual form of aisle vault appears at Creully (Calvados)[146]

(twelfth century), where the aisles are covered with a half tunnel vault

intersected toward the outer wall by lunettes, which thus convert it

into a semi-groined vault. Its obvious advantage lies in the combination

of inward pressure, which it exerts in support of the nave vaults, with

the added window space which it affords without increasing the height of

the exterior walls.

RIBBED VAULTS

The introduction of ribs beneath the diagonal intersections of groined

vaulting gradually brought about a revolution in Mediaeval building, and

transformed the massiveness of Romanesque construction into the light

and graceful architecture of the Gothic era. Much has been written in an

effort to discover the origin of the new system. It is not, however, the

intention here to add to the number of theories advanced, except in an

incidental manner, but rather to classify the various forms of ribbed

vaulting as applied to naves, choirs, and aisles of the churches

following immediately after those of the Romanesque period which have

just been described. As a geographical basis is no longer practical for

such a classification, because of the widespread distribution of the new

method of construction, a structural basis will be substituted, and the

vaults will be divided into two major groups according as they were used

over square or rectangular nave bays, and then subdivided according to

their minor characteristics.

RIBBED VAULTS OVER NAVES WITH SQUARE BAYS

Lombardy affords the first examples of ribbed vaults over nave bays of

square plan. According to Rivoira[147] the earliest are in the church of

Santa Maria e San Sigismondo at Rivolta d’Adda[148] (before 1099),

though this was closely followed by the more important church of Sant

Ambrogio at Milan (between 1088-1128) (Fig. 18), which furnishes an

admirable example of the Lombard type. Its nave is divided into four

great square bays, each corresponding to two bays in the side aisles.

(Plate I-a.) Of these the eastern bay is treated as a crossing and

covered by a dome above a lantern on squinches, but the remaining three

have four-part domed up vaults with heavy ribs of square section, used

not only transversely and along the walls but also diagonally, thus

forming a complete system or skeleton of arches beneath the vault

surface in the manner of true Gothic architecture. But there are many

reasons to believe with Porter[149] that the builders of Lombardy

employed these ribs purely as a permanent centering of masonry,--which

was less expensive than a temporary centering of wood in a country where

the latter material was very scarce,--and that they failed to appreciate

the fact that such ribs made possible a great reduction in the weight of

the panels, or web. of the vault, and in other ways could be made to aid

in reducing and concentrating its pressures. The masonry of the vault is

still excessively

[Illustration: PLATE I]

[Illustration: FIG. 18.--MILAN, SANT’ AMBROGIO.]

thick,--between sixteen and twenty inches,--and would stand equally well

were the ribs removed. Moreover its thrust is so great that the builders

dared not raise its imposts sufficiently high to admit of a clerestory

beneath the formerets, and instead of rendering possible a lighter

construction as Gothic vaults were destined to do, these vaults of

Saint’ Ambrogio required for their support a wall forty inches thick and

ramping walls above the transverse arches of the triforium together with

interior tie-rods and wooden chains in the masonry[150] to offset their

severe outward thrust. All these facts show that the Lombard vaults are

still fundamentally Romanesque in type. Even in San Michele at Pavia

(early twelfth century), where the system was a little more developed,

in that a small clerestory was introduced, the principles were still the

same as in Milan. As a matter of fact, the Lombard builders never made

any further advance in the handling of ribbed vaults, and even went

backward rather than forward. For the builders found that groined vaults

of domed up type could be built so lightly as to require but little

centering, and a return to this simple form was made in such churches

as San Lanfranco at Pavia.[151] Later on, in the thirteenth and

fourteenth centuries, French methods of ribbed vaulting were introduced,

but throughout the whole period of Lombard supremacy the tendency was to

avoid vaulting entirely, and when adopted, it was of the heavy character

just described.

THE SYSTEM OF ALTERNATE SUPPORTS

The Lombard churches are important in the present connection, however,

because of the method in which they are divided into vaulting bays. They

furnish the earliest examples of the system of alternate light and heavy

supports,--employed according to Cattaneo[152] as early as 985 in the

three original bays of SS. Felice e Fortunato at Vicenza. This system of

piers with alternate transverse arches produces one square[153] bay in

the nave to two square bays in the side aisles, and it occurs not only

in vaulted churches but also in others in which a wooden roof rests upon

these transverse supports.[154] Its advantage in the vaulted churches is

particularly important, however, and of a two-fold character. In the

first place, it renders the four enclosing arches uniform, and it makes

them as nearly as possible of equal span with the diagonals.[155] And in

the second, it saves a considerable amount of centering by rendering

possible the construction of a vault covering a space corresponding to

two rectangular bays on four instead of seven ribs.[156]

Outside of Lombardy, the four-part cross-ribbed vault over square nave

bays was but seldom employed in churches with side aisles also divided

into square compartments. It appears, however, in the cathedral of Le

Mans, (Sarthe) (middle of the twelfth century), where it would seem to

be due to the influence of the neighboring single aisled churches of

Anjou,--which are later discussed,--and it was frequently used in

reconstructing the vaults of the Rhenish school. In the Gothic period

also, the system occasionally appears in a modified form, and naturally

enough these revivals occur where Norman and Rhenish Romanesque had

caused the principles of Lombard architecture to be strongly entrenched.

Thus the church of Saint Legerius at Gebweiler[157] (cir. 1182-1200)

furnishes a Rhenish, and the choir of Boxgrove Priory church (cir.

1235), an English application of this method. In the latter, the vaults

are no longer highly domed up, and are therefore far removed from their

Lombard prototypes, only the general division of the church reflecting

this influence.

NAVES WITHOUT SIDE AISLES

More important by far, are the churches without side aisles but with

naves in square bays with four part cross-ribbed vaults. This method is

to be seen in the cathedral of Fréjus (Var),[158] which is considered by

Porter[159] to exhibit the earliest extant ribbed nave vaults in France.

These are distinctly of Lombard type, and would seem to show a strong

Lombard influence entering France from the south. It may possibly be

that this same influence followed the route taken earlier by the dome on

pendentives, and thus gave rise to the domed up ribbed vault so common

in the churches of Anjou.[160] Of these latter, the cathedral of Saint

Maurice at Angers (Maine-et-Loire) (Fig. 19), presents perhaps the best

existing example. Its nave vaults which date from as early as 1150[161]

are among the largest and finest in France, having a span of some

fifty-six feet. As in Lombardy, the crown is highly domed up while to

facilitate the construction of the web of the vault with the least

possible centering, pointed diagonals and enclosing arches are employed.

By this means the entire vault was constructed on the ribs with no

centering at all for the lower courses, and a simple _cerce_, a device

consisting of two curved boards sliding along each other, for those

near the crown. At the same time the outward thrusts were greatly

reduced by the pointed section of the vault.

ANJOU RIDGE RIBS

FIG. 19.--ANGERS, CATHEDRAL.

Since the Anjou churches possessed naves of wide span, it is not

surprising to find that their builders soon added ridge ribs beneath the

vault. That these were not mere cover-joints to conceal an irregular

intersection of the masonry, as Choisy suggests,[162] would seem to be

proved by the fact that the courses meet in a straight line at the ridge

in by far the greater number of Anjou churches in which they are

employed,--for example in La Couture at Le Mans (Fig. 20),

Airaines,[163] and numerous churches with small torus ribs, as well as

by the fact that such ridge ribs are sometimes omitted even when the

masonry is laid up in courses of equal width and therefore

interpenetrating at the ridge, as in Avesnières (Mayenne)[164] near

Laval. If not, however, primarily a cover-joint, these ribs did at least

possess both a structural and decorative quality. In the first place

they helped to keep the keystone of the diagonals rigidly fixed during

the building process, and furthermore, they gave an absolutely straight

line to the vault crown which was always difficult to adjust,

particularly in a vault of large size. One of the best and earliest

examples of the employment of such ribs appears in the nave of Notre

Dame-de-la-Couture at Le Mans (Fig. 20) which dates from about 1200, and

a later example is afforded by the church of Saint-Avit-Sénieur

(Dordogne),[165] where the vaults are of the thirteenth century and

replace an original series of domes on pendentives of true Perigord

type.

[Illustration: FIG. 20.--LEMANS, NOTRE DAME-DE-LA-COUTURE.]

In all of the Anjou vaults thus far discussed, the ribs are of

comparatively heavy section and placed entirely beneath the vault

surface, but there was to be a decided change in the thirteenth

century. It has already been noted that domed up vaults could be erected

almost without centering and exerted little if any pressure upon the

ribs beneath them. Realizing this, the builders of Anjou soon began to

reduce the size of the ribs until they became little more than torus

mouldings running along the groin and ridge of the vault. As an actual

fact, however, these torus mouldings were carved upon a sunken rib flush

with the surface of the panel, which, if it no longer furnished a

support for the vault, at least formed a sort of permanent centering

dividing the surface to be vaulted into distinct severies and marking

the line of their intersection in an absolutely correct curve. Such

vaults are closely allied to those of groined type, the ribs playing

practically the same part as those of brick in Roman concrete vaulting.

Since, however, in the Anjou system the ribs always were merely a

permanent centering which could easily be removed without destroying the

vault, a sunken centering was quite as efficient in serving the purpose

of vault division while the torus afforded a certain amount of surface

decoration.

Of this typical Anjou construction, there are numerous examples. At

Poitiers, in the church of Sainte Radegonde the ribs are of reduced size

but not quite flush with the vault surface and the same is true at

Saint-Hilaire--Saint-Florent near Saumur (Marne-et-Loire),[166] while

the choir and transept of Angers cathedral (Fig. 19), and the later bays

of the cathedral of Poitiers furnish examples of the standard type.

After a short period of experiment, the builders of Anjou became very

skillful in the construction of these ribs and vaults and frequently

employed them over bays of unusual plan and elevation as, for example,

in the chapel north of the choir aisle in Saint Serge at Angers (Fig.

21).