vaulting as made by himself, and with the words beneath written at the foot of two of them.
“The chief builder took the measure of the arch, wliich you wiU find marked in red, for that of the whole vaulting, but when he came to the centre of the half-circle, which is at the summit of the same, he perceived his error as here seen in the design marked in black. But with this error it is that the work has been proceeding, insomuch that a large number of the stones will have to be displaced; for in the whole vaulting there is no masonry of bricks, all is in travertine, and the diameter of the arch, exclusive of the cornice which borders it, is twenty-two palms. This mistake has been committed because my advanced age prevents me from visiting the building so frequently as I could wish, although I had prepared an exact model of the work, as I do of every thing; and whereas, I thought that part of the fabric was finished, it will now not be completed during the whole winter. If a man could ever die of shame and grief, I should not be living now. I beg you to account to the Duke for my not being at this moment in Florence.”
On another of the designs, wherein Michelagnolo had drawn the plan of the building, he wrote as follows:—
“Messer Giorgio,—To the end that the difficulty of the vaulting may be the more clearly comprehended, it becomes needful to describe the construction from the ground upwards. It was necessary to divide it into three sections, corresponding with the windows beneath, which are separated by piers; and these sections you see proceeding in the form of pyramids towards the inner centre of the highest point of the vaulting, being in perfect harmony with the basement and sides thereof. But it was needful that the work should be regulated by a large number of centres for supporting the arches, which should have been constantly changed on all sides, and from point to point, for all which no fixed rule could be given; the circles and squares approaching the centre of their deepest part having to be diminished, and to cross each other in so many directions, and to proceed to so many points, that it is without doubt exceedingly difficult to find the true proportions for bringing all to perfection. Yet, having the model—which I make for all things, they ought not to have committed so great an
