Cross section of the dome


Creator: Piero Sanpaolesi
Title:  Axonometric view of the cupola,
Medium: Architectural Drawing
Date:  c. 1941

As seen in the cross section above, the dome of Santa Maria del Fiore is actually composed of two domes, an inner and outer dome, as well as horizontal stone chains and vertical ribs.

As per the resolution of 1367, there were to be no buttresses of any type used to support the dome.  Thus Brunelleschi had to design a new way of constructing the immense dome over an existing octagonal drum.  (Fanelli and Fanelli, 14) King succinctly states that “this design represents a remarkable leap of faith.  No dome approaching this span had been built since antiquity, and with a mean diameter of 143 feet and 6 inches would exceed that of even the Roman Pantheon”.  (King, 9)  In addition to being the widest dome ever built, it would also be the highest.  (King, 9)

The dome itself has a pointed profile rather than the hemispheric dome of the Pantheon and is known as a pointed fifth.  In this way, the thinning of the architectural elements as the hight increased worked to keep the immense load from imploding on itself.  (Fanelli and Fanelli, 22).  “The key to the whole enterprise was the precise calculation and measurements first of the base of the dome and then of each layer as it rose in a gradually narrowing sequence”. (Battisti, 124)

There is a section of the outer dome that was built after the death of Filippo Brunelleschi, and this is seen in one section on the outside of the dome that was to be a gallery.  However, only one section of the eight sides was built, because “it did not match Filippo’s design, it was abandoned and left unfinished upon the advice of Michalangelo Buonarroti”. (Vasari, 136)  This gallery, seen on only one side of the octagon of the drum of the dome was called by Michaelangelo “a cage for crickets”, and was viewed as not in keeping with the rest of the architecture of the dome.  Thus, the remaining seven sides of the proposed gallery were never completed.

Works Cited:

Battisti, E.  Filippo Brunelleschi. Phaidon Press Ltd. 2011
Fanelli, G and Fanelli, M. Brunelleschi’s Cupola, Past and Present of an Architectural Masterpiece.  Mandragora s.r.l. 2004
Vasari, G. The Lives of the Artists. Oxford University Press, translated by J.C. Bondanella and P. Bondanella. 2008

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