324 THE STONES OF VENICE DECORATION

its alabaster covering, literally marble defensive armour, riveted together in pieces, which follow the contours of the building. Now, on the wall, these pieces are mere flat slabs cut to the arch outline; but under the soffit of the arch the marble mail is curved, often cut singularly thin, like bent tiles, and fitted together so that the pieces would sustain each other even without rivets. It is of course desirable that this thin sub-arch of marble should project enough to sustain the facing of the wall; and the reader will see, in Fig. 57, that its edge forms a kind of narrow band round the arch (b), a band which the least enrichment would render a valuable decorative feature. Now this band is, of course, if the soffit pieces project a little beyond the face of the wall-pieces, a mere fillet, like the wooden gunwale in Plate 9; and the question is, how to enrich it most wisely. It might easily have been dogtoothed, but the Byzantine architects had not invented the dogtooth, and would not have used it here, if they had; for the dogtooth cannot be employed alone, especially on so principal an angle as this of the main arches, without giving to the whole building a peculiar look, which I can no otherwise describe than as being to the eye, exactly what untempered acid is to the tongue. The mere dogtooth is an acid moulding, and can only be used in certain mingling with others, to give them piquancy; never alone. What, then, will be the next easiest method of giving interest to the fillet?

§ 13. Simply to make the incisions square instead of sharp, and to leave equal intervals of the square edge between them. Fig. 58 is one of the curved pieces of arch armour, with its edge thus treated; one side only being done at the bottom, to show the simplicity and ease of the work. This ornament gives force and interest to the edge of the arch, without in

[Version 0.04: March 2008]