with these words written at the foot of two
of them:

"The centre marked with red was used by the capomaestro over the body
of the whole vault; then, when he began to pass to the half-circle,
which is at the summit of the vault, he became aware of the error
which that centre was producing, as may be seen here in the design,
marked in black. With this error the vault has gone so far forward,
that we have to displace a great number of stones, for in that vault
there is being placed no brick-work, but all travertine, and the
diameter of the circle, without the cornice that borders it, is
twenty-two palms. This error, after I had made an exact model, as I do
of everything, has been caused by my not being able, on account of my
old age, to go there often; so that, whereas I believed that the vault
was now finished, it will not be finished all this winter, and, if it
were possible to die of shame and grief, I should not be alive now. I
pray you account to the Duke for my not being at this moment in
Florence."

[Illustration: S. PETER'S

(_After =Michelagnolo=. Rome_)

_Alinari_]

And continuing in the other design, where he had drawn the plan, he
said this:

"MESSER GIORGIO,

"To the end that it may be easier to understand the difficulty of the
vault by observing its rise from the level of the ground, let me
explain that I have been forced to divide it into three vaults,
corresponding to the windows below divided by pilasters; and you see
that they go pyramidally into the centre of the summit of the vault,
as also do the base and sides of the same. It was necessary to
regulate them with an infinite number of centres, and there are in
them so many changes in various directions, from point to point, that
no fixed rule can be maintained. And the circles and squares that come
in the middle of their deepest parts have to diminish and increase in
so many directions, and to go to so many points, that it is a
difficult thing to find the true method. Nevertheless, having the
model, such as I make for everything, they should never have committed
so great an error as to seek to regulate with one single centre all
those three shells; whence it has come about that we have been obliged
with shame and loss to pull down, as we are still doing, a great
number of stones. The vault, with its sections and hewn stone-work, is
all of travertine, like all the rest below; a thing not customary in
Rome."

Michelagnolo was excused by Duk