Fow exactly Filippo calculated the disposition of the bricks and the
massive stone beams is another of the dome's mysteries. F^owever, in
Historia Jtorentinorum, written sometime during the 1490s, the humanist poet
and historian Bartolomeo Scala offers a hint as to how he might have done it: Tor, when the centre [of the dome] was pinpointed and marked,' Scala
clamis, Tilippo stretched a cord from the centre to the circumferences.
Carrying on this process around in a circle, he determined in what order
and according to what curvature the bricks and mortar were to be placed
on the wall by the masons.