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 ECCLESIASTICAL

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ECCLESIASTICAL

plainly desirable to substitute for a vaulting of uni- form thickness a framework of ribs on which a com- paratively thin layer of stones (cut to the requisite curvature) could be laid, and as far as possible to lighten the whole construction by moulding the ribs and likewise the columns which supported the vault- ing. The same principle of aiming at lightness of con- struction led to the elimination, as far as possible, of all masses of solid masonry above the columns and arches of the nave. This was done by the enlarge- ment of the windows and the development of the tri- forium, till the entire building, with the exception of the buttresses, and of the spandrels below the trifor- ium, became a graceful framework of grouped shafts and interlacing ribs (Moore, op. cit., 17). The final stage in the evolution of architecture of the pointed arch was not, however, reached, until, for the solid Romanesque buttresses, which rested on the vaulting of the aisles, and which were not only clumsy but often proved inadequate for their purpose, the genius of the Gothic builders hit upon the epoch-making de- vice of the flying buttress. By means of this device the thrust of the main vaulting was not, indeed, as has been too often said, ''met by a counter-thrust", but was transmitted to the solid buttresses, mostly weighted with pinnacles, which were now built outwards to a great distance from the aisles, and the spaces between which were sometimes utilized, and might with advan- tage have been more often utilized, for a range of lat- eral chapels. (Bond, op. cit., 754; cf. Moore, op. cit., 20.) The subject of Gothic architecture in its details is, however, one that needs separate treatment, and for present purposes this very inadequate indication of some of the general principles involved in its devel- opment must suffice.

The Circular Church and its Deriv.\ti\"es. — It was stated at the outset of this article that all ecclesi- astical architecture may be said to have been devel- oped from two primitive germs, the ol>long and the circular chamber. Of those very numerous churches, principally, but by no means exclusively, Eastern or Italian, which may be regarded as the products of the second line of development, we shall speak very briefly. That a circular chamber without any kind of annex was unsuitable for the ordinary purposes of public worship is plain enough. And the most obvi- ous modification of this rudimentary form was to throw out a projecting sanctuary on one side of the building, as in St. George's, Thessalonica, or in the lit- tle church of S. Tommaso in Limine, near Bergamo. It was hardly less obviously convenient to build a pro- jecting porch or narthex on the opposite side, as in St. Elias's, also at Thessalonica, and to complete the cross by means of lateral projections, as in the sepul- chral chapel of Galla Placidia at Raverma. Thvis it was that churches having the form of a Greek cross, as well as other varieties of what Cierman writers call the Centrnlbau, may be said to owe their origin to a very simple process of evolution from the circular domed building. Among the almost endless varieties on the main theme may be here enumerated: (1) buildings in which a circvilar, or polygonal, or quadrilateral aisle, whether in one or more stories, surrounds the central space; (2) buildings in which, though the principal open space is cruciform, and the whole is dominated by a central cupola, the ground-plan shows a rectan- gular outline, the cross being, as it were, "boxed" within a square; and (3) buildings in which one of the arms of tlie cross is considerably elongated, as in the Duomo at Florence, St. Peter's in Rome, and St. Paul's in London. The last-named modification, it is to be observed, had the effect of assimilating the ground-plan of those great churches, and of many les- per examjiles of the same character, to that of the Romanesque and Gothic cruciform buildings whose genealogical descent from the columned rectangular basilica is incontestable. Among ecclesiastical edi-

fices of historical importance or interest which arc either circular or polygonal, or in which the circular or polygonal centre predominates over all subsidiary parts of the structure, may be mentioned the Pan- theon in Rome, St. Sergius at Constantinople, S. Vitale at Ravenna, S. Lorenzo at Milan, the great Ijaptister- ies of Florence, Siena, and Pisa, and the churches of the Knights Templars in various parts of Europe. St. Luke's at Stiris in Phocis, besides being an excellent typical instance of true Byzantine architecture, af- fords a good example of the " boxing" of a cruciform building of the C5reek tj-pe, by enclosing within the walls the square space between the adjacent Umbs of the cross.

Practically, however, the full development of cruci- form from circular buildings became possible only when the problem had been solved of roofing a square chamber with a circular dome. This has in some cases been done by first reducing the square to an oc- tagon, by means of "squinches" or "trompettes", and then raising the dome on the octagon, by filUng in the obtuse angles of the figure with rudimentary penden- tives or faced corbeUing. But already in the sixth century the architect and bulkier of Santa Sophia had showetl for all time that it was possible, by means of "true" pendentives, to support a dome, even of im- mense size, on four arches (with their piers) forming a square. The use of pendentives being once understood, it became possible, not only to combine the advan- tages of a great central dome with those of a cruci- form church, but also to substitute domical for barrel- vaulting over the limbs of the cross, as at S. Marco, Venice, St-Front, Perigueux, and S. Antonio, Padua, or even to employ domical vaulting for a nave divided into square bays, as in the cathedral at .\ngouleme and other eleventh-century churches in Pcrigord, in S. Sal- vatore at Venice, in the London Oratory, and (with the difference that saucer domes are here employed) in the Westminster Cathedral. Nor should it be for- gotten that in the nave of St. Paul's, London, the archi- tect had shown that domical vaulting is possible even when the bays of nave or aisles are not square, but pro- nouncedly oblong. Indeed, if account be taken of the manifold disadvantages of barrel- vaulting as a means of roofing the nave of a large church, it may safely be said that the employment of some form of the dome or cupola is as necessary to the logical and structural per- fection of the architecture of the round arch as ribbed groining and the use of flying buttresses are necessary to the logical and structural perfection of the archi- tecture of the pointed arch.

Systems and Styles of Architecture in Rela- tion TO Modern Needs. — A word must now be said, in conclusion, as to the merits of the several systems and styles of architecture, more especially in relation to the needs of our own day. Of systems, indeed, there are in truth only three, the trabeate or that of which the horizontal lintel may be regarded as the generating element, and which of necessity postulates a timber roof; that of the round arch, which by virtue of the law of economy postulates, as has been said, the use of domical rather than barrel-vaulting; and that of the pointed arch, which, if carried to perfection, pos- tulates ribbed groining and the use of the flying but- tress. The second system, however, admits of two methods of treatment which are sufficiently distinc- tive to be classed as two "styles", viz. the neo-classi- cal, or Renaissance, and the Byzantine, and which shall be particularized presently.

Now the trabeate system, or that of the timber roof, may be very briefly dismissed. In the great majority of cases we must, indeed, of necessity be content with such a covering for our churches; but no one would choose a wooden roof who could afford a vaulted build- ing. Again, the various types of Romanesque archi- tecture, with their imperfect and tentative methods of vaulting, though historically of great interest, should