f solid stone bound to the buttresses to the height of twenty-four
braccia, and thence upward they shall be constructed of brick or of
spongite (spugne), as shall be determined on by the masters who build
it, they using that which they consider lightest. On the outside, a
passage or gallery shall be made above the windows, which below shall
form a terrace, with an open parapet or balustrade two braccia high,
after the manner of those of the lower tribunes, and forming two
galleries, one over the other, placed on a richly decorated cornice, the
upper gallery being covered. The rain-water shall be carried off the
cupola by means of a marble channel, one third of an ell broad, the
water being discharged at an outlet to be constructed of hard stone
(pietra forte), beneath the channel. Eight ribs of marble shall be
formed on the angles of the external surface of the cupola, of such
thickness as may be requisite; these shall rise to the height of one
braccia above the cupola, with cornices projecting in the manner of a
roof, two braccia broad, that the summit may be complete, and
sufficiently furnished with eaves and channels on every side; and these
must have the form of the pyramid, from their base, or point of
junction, to their extremity. Thus the cupola shall be constructed after
the method described above, and without framework, to the height of
thirty braccia, and from that height upwards, it may be continued after
such manner as shall be determined on by the masters who may have to
build it, since practice teaches us by what methods to proceed.'

"When Filippo had written the above, he repaired in the morning to the
tribunal, and gave his paper to the syndics and wardens, who took the
whole of it into their consideration; and, although they were not able
to understand it all, yet seeing the confidence of Filippo, and finding
that the other architects gave no evidence of having better ground to
proceed on,--he moreover showing a manifest security, by constantly
repeating the same things in such a manner that he had all the
appearance of having vaulted ten cupolas:--the Syndics, seeing all this,
retired apart, and finally resolved to give him the work; they would
have liked to see some example of the manner in which he meant to turn
this vault without framework, but to all the rest they gave their
approbation. And fortune was favorable to this desire: Bartolomeo
Barbadori having determined to build a chapel in Santa Feli