CONSTRUCTION XI. THE ARCH MASONRY 167

of the building, and many other circumstances may occur to hinder us.

§ 6. But if we are not sure that we can put weight above it, we are perfectly sure that we can hang weight under it. You may always thicken your shell inside, and put the weight upon it as at x x, in d, Plate 3. Not much chance of its bursting out at p now, is there?

§ 7. Whenever, therefore, an arch has to bear vertical pressure, it will bear it better when its shell is shaped as at b or d, than as at a: b and d are, therefore, the types of arches built to resist vertical pressure, all over the world, and from the beginning of architecture to its end. None others can be compared with them: all are imperfect except these.¹

The added projections at x x, in d, are called CUSPS, and they are the very soul and life of the best Northern Gothic; yet never thoroughly understood nor found in perfection, except in Italy, the Northern builders working often, even in the best times, with the vulgar form at a.

The form at b is rarely found in the North: its perfection is in the Lombardic Gothic; and branches of it, good and bad according to their use, occur in Saracenic work.

§ 8. The true and perfect cusp is single only. But it was probably invented (by the Arabs?) not as a constructive, but a decorative feature, in pure fantasy; and in early Northern work it is only the application to the arch of the foliation, so called, of penetrated spaces in stone surfaces, already enough explained in the Seven Lamps, Chap. III.,

§ 18, et seq.² It is degraded in dignity, and loses in usefulness, exactly in proportion to its multiplication on the arch. In later architecture, especially English Tudor, it is sunk into dotage, and becomes a simple excrescence, a bit of stone

¹ [For a reference to this passage, with its demonstration of the constructive value of the Gothic cusp-a statement “first denied, and then taken advantage of, by modern architects”-see Lectures on Architecture and Painting, § 58 n. Ruskin refers again to his discovery in a letter to Coventry Patmore: see above, Introduction, p. xli.]

² [Vol. VIII. p. 126.]

[Version 0.04: March 2008]