<;<>THir AK< nm:<T( m; 



315 



Tli'- following short sketch nf the history of the 

 vault in;,' will show how this occurred. 



Tlir Ionian Iwtsilicas, and, like them, the early 

 rini>iiaii cliurcln-s (for ground-plan see the 

 article I! VSII.ICA), were divided into a central 

 unl two or four side-aisles, the former separ- 

 ated fiom the latter by one or two rows of 

 column* on each side. These columns carried 

 ai<-iii-s on which icsird dm side- walls of the nave, 

 which were carried sufficiently high to clear the 

 tools of the side aisles, and admit windows to light 

 tlii' central nave. This row of windows afterwards 

 me the Gothic Clerestory (q.v.). At the east 

 end of the nave was a great arch leading into an 

 o|it'n space, in the centre of which was the apse. 

 Tin' latter was semicircular in plan, and was 

 usually roofed with a vault in the form of a semi- 

 domc. This feature was also afterwards more fully 

 developed, and surrounded with radiating chapels 

 in Gothic churches. The nave and side-aisles were 

 originally roofed with wood, but, owing to their 

 frequent destruction by fire, it became necessary 

 to cover the churches with a more enduring kind 

 .I' construction. It was then attempted to intro- 

 duce vaulting; but the skill of the workmen 

 had degenerated, and many efforts were needed 

 In-fore a system suitable for the requirements 

 of the penod and within the capacity of the 

 builders was arrived at. But, as we snail presently 

 see, when the principle of pointed vaulting was 

 once grasped, the development of the style followed 

 with astonishing rapidity. To trace the progress of 

 vaulting from the early simple tunnel-vault copied 

 from the work of the Romans to the fully-developed 

 and magnificent groins of Gothic cathedrals is a 

 most interesting inquiry ; and indeed includes the 

 history of the development of Gothic architecture. 

 There is one consideration which will help to 

 explain how the Roman vaults came to be gradually 

 modified and new forms sought out. To the Roman 

 emperors who built the splendid vaults of the 

 baths, and who had a subdued world at command, 

 materials and labour were of small consideration. 

 They could therefore afford to build in a style 

 which required perfect materials and workmanship. 

 But medieval princes and bishops could obtain 

 neither. To economise these, therefore, the utmost 

 skill and attention were required. It was necessary 

 to avoid those large and expensive materials of 

 which the Romans were so lavish, and to adopt the 

 sunniest and easiest forms of construction. 



Toe first vaults tried were simple semicircular 

 tunnel-vaults. It was found that these, besides 

 being very gloomy, required very massive walls to 

 resist their thrust. An attempt was then made to 

 relieve this thrust by transverse arches (a, a, fig. 

 1 ) thrown across at intervals under the tunnel- 

 rault, to act as strengthening ribs. This idea was 



Fig. 1. 



also borrowed from Roman precedent. Buttresses 

 with a slight projection were applied outside to 

 abut the transverse arches, and a beam of wood 

 was sometimes introduced at the wall-heat! from 

 buttress to buttress to assist in opposing the thrust 

 nf the vault. 



This wa. the first attempt to concentrate the 

 weight of t ,e vault on single points. In the side- 

 aisles, when? the span was small and manageable, 

 the Uoiuai. intersecting vaults (6, 6, fig. 1) were 



used ; and as the main roofs with their tunnel- 

 vaulting were found very gloomy and ill lighted, it 

 was considered desirable that similar intersecting 

 vaults should IK- used to cover them also, w> as to 

 admit of the clerestory windows leing raised in 

 order to light the vaulting. But how wa- t hi- to 

 ! managed with the inferior material- and work- 

 manship at command? If the transverse archr* 

 AB, CD (fig. 2) 

 are semicircular, 

 and the .-nie 

 arches AC, BD 

 the same the 

 vault being 

 formed by two 

 intersecting 

 cylinders then 

 t in- intersecting 

 groins AD and 

 CB must be Fi - 2 - 



elliptical. This 



was a difficult form of construction : the medieval 

 builders found it easier to construct the groin or 

 diagonal arches of a circular form with radius EA 

 (fig. 3), and to fill in the triangular spaces ABE, 

 &c. , with slightly domed vaults. These semi- 

 circular edges or groins gradually came to form 

 independent ribs. At first they were only marked 

 by a bead on the angle, but being the chief con- 

 structional element of the vaulting they soon came 

 to be distinctly separated from the rest of the 

 vault as independent members with the name of 

 groin ribs, the development of which played so 

 important a part in Gothic vaulting. When the 

 space to be covered was square the above form of 

 vault was found to answer, and each bay of the nave 

 usually included two bays of the side-aisles, as 

 in fig. 4. But this arrangement looked awkward 

 externally, the windows of the clerestory not group- 

 ing well with those of the side-aisles. A transverse 

 arch (a, a, fig. 3) was then introduced, carrying up 

 the design from the nave piers to the vaulting. 



Fig. 3. 



This form of vault is called hexapartite. All the 

 above varieties of vaulting were fully developed 

 during the llth and 12th centuries in the round - 

 arched styles of the Rhine. 



In France these forms were also tried ; but it 

 was found that the semicircle is not a good form of 

 arch unless loaded on the haunches, many of the 

 churches which were vaulted in this manner during 

 the llth century having to be buttressed or rebuilt 

 in the 12th and 13th centuries. In Provence 

 (where the Roman influence continued to be 

 strongly felt, owing to the large numl>er of Roman 

 buildings still surviving in the country) the tunnel- 

 vault (fig. 4) was in use probably as early as the 

 9th or l()th century. But the form of the vault 

 adopted then differed from that of the Romans in 

 being pointed instead of round. The pointed 

 form may have been lorrowed from the Moore in 

 Spain, by whom it was used as a decorative feature, 

 l.ut it was undoubtedly adopted in Provence as a 

 simply-constructed method ot vaulting. This form 

 of arch was thus probably suggested in the 12th 

 century to the architects of the north of France, 

 who at once saw how well it would overcome the 



