which the inner vault is supported will be bound and strengthened; these fastenings of oak shall then be covered with plates of iron, on account of the staircases.  The buttresses are all to be built of macigno, or other hard stone, and the walls of the cupola are, in like manner, to be all of 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 Felicita, and having spoken concerning it with Filippo, the latter had commenced the work, and caused the chapel, which is on the right of the entrance, where is also the holy water vase (likewise by the hand of Filippo), to be vaulted without any framework.