wooden architecture, and therefore as legitimately rivets and solderings in stone; neither can we well deny to the Gothic architect the power of supporting statues, pinnacles, or traceries by iron bars; and if we grant this, I do not see how we can help allowing Brunelleschi his iron chain around the dome of Florence, or the builders of Salisbury their elaborate iron binding of the central tower[1]. If, however, we would not fall into the old sophistry of the grains of corn and the heap, we must find a rule which may enable us to stop somewhere. This rule is, I think, that metals may be used as a cement, but not as a support. For as cements of other kinds are often so strong that the stones may easier be broken than separated, and the wall becomes a solid mass, without for that reason losing the character of architecture, there is no reason why, when a nation has obtained the knowledge and practice of iron work, metal rods or rivets should not be used in the place of cement and establish the same or a greater strength and adherence, without in any wise inducing departure from the types and system of architecture before established; nor does it make any difference except as to sightliness, whether the metal bands or rods so employed, be in the body of the wall or on its exterior, or set as stays and cross-bands; so only that the use of them be always and distinctly one which might be superseded by mere strength of cement; as for instance if a pinnacle or mullion be propped or tied by an iron band, it is evident that the iron only prevents the separation of the stones by lateral force, which the cement would have done, had it been strong enough. But the moment that the iron in the least degree takes the place of the stone, and acts by its resistance to crushing, and bears superincumbent weight, or if it acts by its own weight as a counterpoise, and so supersedes the use of pinnacles or buttresses in resisting a lateral thrust, or if, in the form of a rod or girder, it is used to do what
- ↑ 8. p. 43. 'The Builders of Salisbury': 'This way of tying walls together with iron, instead of making them of that substance and form, that they shall naturally poise themselves upon their buttment, is against the rules of good architecture, not only because iron is corruptible by rust, but because it is fallacious, having unequal veins in the metal, some places of the same bar being three times stronger than others, and yet all sound to appearance.' (Survey of Salisbury Cathedral in 1668, by Sir C. Wren.) For my own part, I think it better work to bind a tower with iron, than to support a false dome by a brick pyramid.
