have wandered still farther, as we shall see, from the true path of monumental art.
Moreover, when we consider that a dome set within its drum is not only stronger, but that it is also much better for interior effect, the dome of the Pantheon still remaining the grandest and most impressive arched ceiling of its kind in the world, the unbuttressed modern domes, with their manifold extraneous and hidden devices for security, appear still less defensible.
But in the architectural thought of the Renaissance little heed was given to structural propriety or structural expression, and the Italian writers, who have largely shaped our modern architectural ideas, have not only failed to recognize the inherent weakness of such a building as the dome of Florence, but have even considered the work praiseworthy on account of those very characteristics which make it weak. Thus Sgrilli lauds Brunelleschi for having had the "hardihood to raise to such a height the greatest cupola which until its time had ever been seen, upon a base without any abutments, a thing that had not before been done by any one."[1] And Milizia says, "It is worthy of special notice that in the construction of this cupola there are no visible abutments."[2]
As to the permanent stability of this dome various opinions have been held by the experts among the older writers.[3] Its form is, as we have seen, as favourable to stability as it would be possible to make that of any vault which could be properly called a dome. It appears to the inexperienced eye as stable as a crest of the Apennines. Every precaution as to material and careful workmanship seems to have been taken to make it secure. The wall of the drum on which it rests is five metres in thickness, and the solid base of the dome itself is built, if the architect's scheme was carried out as he had stated it before the Board of Works, of large blocks of hard stone, thoroughly bonded and clamped with iron. The lower system is sufficiently strong, and appears to rest on a solid foundation. But nevertheless there are ruptures in various parts of the structure
