The dome of Florence is indeed a remarkable piece of construction, and it is no less remarkable as a work of art. In beauty of outline it has not, I think, been approached by any of the later elevated domes of which it is the parent. Yet with all of its mechanical and artistic merit, the scheme is fundamentally false in principle, since it involves a departure from sound methods of dome construction. A bulging thin shell of masonry on a large scale cannot be made secure without abutment, much less can such a shell sustain the weight of a heavy stone structure like the lantern of this monument, without resort to the extraneous means of binding chains. A builder having proper regard for true principles of construction in stone masonry would not undertake such a work. For although it may be possible to give the dome a shape that will be measurably self-sustaining as to thrusts, as Brunelleschi clearly strove to do,[1] it is not possible to make it entirely so, and therefore if deprived of abutment it must be bound with chains. But a structure of masonry which depends for stability on binding chains is one of inherent weakness, and thus of false character.[2]
From these considerations it appears to me that Brunelleschi led the way in a wrong direction, notwithstanding the nobility of his achievement from many points of view. And in following his example modern designers of elevated domes
- ↑ In his explanation of his scheme before the Board of Works, as given by Vasari, Brunelleschi begins as follows: "Considerato le difficultà di questa fabbrica, magnifici Signori Operaj, trovo che non si può per nessun modo volgerla tonda perfetta, atteso che sarebbe tanto grande il piano di sopra, dove va la lanterna, che mettendovi peso rovinerebbe presto." Op. cit., vol. 2, p. 347.
- ↑ It may be thought that this would condemn the use of metal clamps in masonry, such as were inserted in the walls of the Parthenon, or the wooden ties that were, in some cases, used in parts of Gothic buildings. But there is a wide difference between such use of clamps and ties, and the binding chains of the great domes of the Renaissance. In the Greek and Gothic work the masonry forms are favourable to stability independently of the clamps and ties. These were inserted either for security against unusual dangers, as from earthquakes, or for temporary security against rupture while the work was in progress, before the interaction of the parts of the system was fully established; but a dome without abutment violates the constant conditions of stability.
da Opera; come sentiranno nella sua Vita scritta da Diversi." Brunelleschi, in his account of his intentions before the Board of Works (note, p. 19), would not explain his scheme for the scaffolding. He said merely that the vault was to be raised, without centring, to the height of 30 braccia, and from that level upwards, in the manner that should be advised by those who might then have the work in charge.
