This pointed profile was important to the cupola both structurally and
aesthetically. The pointed arch was, of course, the favoured Gothic
method of spanning space: the arches in the nave of Santa Maria del Fiore
are pointed, for example, as are those in the naves of most Gothic
churches. The pointed arch has two distinct advantages over the rounded
or semicircular one that would come to dominate architecture throughout
the Renaissance. The first has to do with proportions, for a pointed arch
rises higher than a semicircular one of equivalent span. In 1367 this factor
no doubt influenced the thinking of the wardens of Santa Maria del Fiore,
for a dome with a pointed profile was able to stand as much as a third
higher than a semicircular one built over a tambour of equal diameter.
Only with a pointed curvature, that is, could the cupola reach the desired
height of 144 hraccia.