nd eight rounds, each range forming recesses that grow
more shallow in succession. The ground of all these displays
extraordinary richness, for Michelagnolo intended to make the ribs and
the ornaments of the said ovals, straight-sided compartments, and
rounds, all corniced in travertine.

It remains for us to make mention of the surface and adornment of the
arch on that side of the vault where the roofing is to go, which
begins to rise from a base twenty-five palms and a half high, which
has at the foot a basement that has a projection of two palms, as have
the crowning mouldings at the top. The covering or roofing with which
he proposed to cover it is of lead, such as covers the roof of the old
S. Pietro at the present day, and is divided into sixteen sections
from one solid base to another, each base beginning where the two
columns end, which are one on either side of it. In each of these
sections, in the centre, he made two windows to give light to the
inner space where the ascent of the stairs is, between the two shells,
so that in all they are thirty-two. These, by means of brackets that
support a quarter-round, he made projecting from the roof in such a
manner as to protect the lofty and novel view-point from the rain. In
a line with the centre of the solid base between each two columns,
above which was the crowning cornice, sprang a rib, one to each, wider
at the foot and narrowing at the top; in all sixteen ribs, five palms
broad, in the centre of each of which was a quadrangular channel one
palm and a half wide, within which is formed an ascent of steps about
one palm high, by which to ascend or descend between the platform at
the foot and the summit where the lantern begins. These are to be
built of travertine and constructed with mortisings, to the end that
the joins may be protected against water and ice during times of rain.

The design for the lantern is reduced in the same proportion as all
the rest of the work, so that, taking lines round the circumference,
everything comes to diminish in exact accord, and with proportionate
measurements it rises as a simple temple with round columns two by
two, like those on the solid bases below. These have pilasters to
correspond to them, and one can walk all the way round and see from
the central spaces between the pilasters, where the windows are, the
interior of the tribune and the church. Above this, architrave,
frieze, and cornice curve in a round, projecting ov