Ser Filippo Brunelleschi
And the dome
Santa Maria del Fiore
in Florence (1420-1446)
November 10th, 2002
When we visit places and see monuments, buildings, museums, paintings
and statues or cities we are usually keen to read our guides for information
about their origins and history. We learn about the "style"
the "school" and for paintings and statues we are usually
informed of the name of the artist: Leonardos Mona Lisa, Michelangelos
Pieta Rondanini, Picassos Guernica.
For buildings, or for very important architectural landmarks, the name
of the architect, engineer or builder is generally neglected: we are
told the height of the skyscraper, the length of the span of a bridge,
or how many millions of cubic meters of water a dam contains.
But not many know who designed and built the Golden Gate? Or who designed
the Empire State Building, or who designed the Grand Coulee Dam?
Galleria Vittorio Emanuele in Milan? The Gold Fields Duct in WA, the
Suez Canal? Every story behind the construction and conception of a
great monument is the story of some strong, forward-thinking person
who passionately wanted and fought, (sometimes for a lifetime) for its
acceptance an construction. Some of these people even lost their lives
in the challenge for the achievement of their vision. I will pay due
respect to a few of the unknown heroes, reminding you of some of the
Some buildings or works of art instead live with the name of the architect
attached to them forever because the story behind them was particularly
harrowing and challenging: the Eiffel Tower, Cheopes Pyramid,
la Cupola del Brunelleschi, Michelangelos Pieta, Leonardos
My lecture today is about la Cupola del Brunelleschi: Brunelleschis
Dome on the Florence Cathedral of Santa Maria del Fiore and I will try
to tell you the story through the narration of the life of Filippo di
Ser Brunellesco known in the Florence of the Renaissance (1400) as Pippo
Vasaris account of Filippo Brunelleschis life starts his
physical description with this very significant statement (my translation):
Many are cruelly bestowed by Nature with deformed bodies and repugnant
features, but have souls of unequalled greatness and courageous hearts,
so that they find no peace in life unless they meet great challenges
and achieve hugely difficult deeds, and when fate delivers base and
vile things into their hands they are able to transform them into wonders.
Therefore one should never disdain people who have not the appearance
of grace and beauty that should be Natures gift. Under the sod
run golden veins.
Or as they say in the North of England "where theres muck
Filippo Brunelleschi 1377-1446
Structural assumption and Massimo Riccis studies.
After considerable research with the available literature and after
a long telephone interview with Massimo Ricci, the most authoritative,
living Brunelleschi dome expert, I have attempted to draft my "structural
assumption" to answer the question "how does the dome
It is important to understand, at least intuitively, the structural
assumption because the "secret" of the dome is the key for
understanding the complex personality of Filippo Brunelleschi.
The discussion on the structural conception of the dome and the theories
explaining on what principle the dome is structurally sound has been
fierce since its first conception and still goes on today. Masssimo
Ricci, architect and professor at the School of Architecture in Florence
has drafted a "regola di costruzione" to explain the
complex dynamics of the structural stability of the dome and he challenges
the whole body of Brunelleschi experts in the most daring way: by building
a scale model of the dome.
Prof. Arch. Massimo Ricci
After speaking with prof. Massimo
Ricci I think that this basic assumption can be plausible (***):
The dome is structurally efficient because Brunelleschi succeeded
in building a "box like" structure (hollow rigid frame)
connecting the outer and inner vaults with the eight "ribs"
(basic point in Massimo Riccis position).
The dome is not originated by the rotation of a curve around a vertical
axis: no such geometry is to be found or alleged to be hidden inside
the masonry mass. (2)
The slant of the layers of bricks is such that the masonry is always
compressed and thus it was possible to erect it without centering.
On account of the specific slant of the layers of bricks the sliding
of the last layer was refrained even by the wet mortar.(see**)
The fishbone helicoidal bricklayers were meant to control the geometry
of the vaults during construction, supplying the reference for the
masons, but had no specific structural function in the finished vaults,
in fact they are weak points in the structure.
The "chains" in stone blocks connected by metal claws and
the wooden "chain" are structurally redundant and they are
clear signs of the uncertainty of Brunelleschi about the efficacy
of his structural intuition (boxlike structure).
The "lantern" on top of the dome increases the compression
on the external layers of the two vaults and contributes to control
the centrifugal thrust.
View of the dome during construction (copyright Paolo Rossi)
The scale model that prof. Riccis is building (detail) (4)
Critical history of the dome
The history of the construction of the dome is a history of conflicts,
contradictions and confrontations. (3)
The first model produced by Neri di Fioravanti (1367) did not solve
the structural problem of the dome: maybe Neri knew how to vault the
octagonal base (the largest ever built), but the model did not show
it. He died without explaining his concept or maybe he himself had
no explanation. Which may be a reason for his death: consumed by the
terror of not being able to implement his commitment. Nevertheless
the builders responsible for the construction of the dome had to take
an oath every year pledging their commitment to build the dome according
to Neris model.
In hindsight the whole thing sounds strange: the authoritative members
of the "opera del Duomo" chose a model in 1367 (Neri di
Fioravanti) with blind faith in the words of Neri (he had designed
the Ponte Vecchio in 1345) that the dome could be vaulted.
With Neris death and no written document to explain how to build
the dome they had to ask for proposals with the competition of 1418.
When they received the proposals they had no clue that could simplify
their choice and they chose Brunelleschi possibly because of the tough
stance that Brunelleschi took in front of them.
According to Vasari the story of the relationship between Brunelleschi
and the Officials of the Opera del Duomo is quite colorful. Brunelleschi
was intolerant and could easily be provoked into fits of rage by the
arrogant ignorance of the bureaucrats. While trying to explain to
the "officials" his concept, sensing their hostility and
prejudice he got very upset and started screaming and insulting the
"officials" to the point that he had to be literally carried
away by the "donzelli" (valets).
It is possible that Brunelleschi was trying to explain things which
were not quite clear to himself either, or that he was trying to explain
without revealing the "secret" of his conception, fearing
that somebody might steal the idea from him.
But their dubious attitude was documented by the fact that they wanted
Lorenzo Ghiberti (a sculptor with no building experience) to work
side by side with Brunelleschi. They did not trust Ghiberti either
and they associated him with a professor of humanities Giovanni da
Prato whose technical competence was even less than Ghibertis.
Brunelleschi loathed Ghiberti and Giovanni da Prato loathed Brunelleschi.
Apparently Ghiberti tried to stay out of trouble, eventually relying
on Brunelleschis competence.
The whimsical trio started the construction in 1420, bickering and
accusing one another of incompetence: the toughest, and the only really
competent one, was Brunelleschi whose model and ways of doing things
were accepted as well as imposed.
The dome construction proceeded according to plans or, rather according
to Brunelleschis strong leadership: after nine years the "Opera
del Duomo" was not yet certain that the dome could be vaulted
without centering: they stated that a decision would have been suggested
by the progress of things. (We will build that bridge when we reach
that river). In public and in front of the Officials Brunelleschi
was adamant he could do without centering, but the adding of "chains"
clearly suggests that deep down he had some doubt. The cracks in 1429
must have been a nightmare for him: but at that point a centering
would not have been feasible anyway: you cannot build centering once
you are half way through the dome because the "adjustments"
or setting in movements of the first half of the dome (built with
no centering) and of the second half (built on the centering) would
have broken the vaults. The chosen course was irreversible.
Brunelleschi completed his dome but he had problems and difficulties
to the end. Two episodes were to damage his authority: the capsizing
in 1427 of the barge Il Badalone that he had designed to transport
huge marble blocks from Pisa to Florence on the river Arno and the
blunder of the Lucca siege in 1430 when he designed a dam to divert
the course of the river Serchio and flood Lucca at the time under
siege of the Florentine armies. The dam did not stand the pressure
of the water.
(**) The "secret"
Brunelleschi is generally referred to as a "Renaissance" genius
or in some literature even as the "father of Renaissance engineering".
I would disagree: he was formally a man of the Renaissance but conceptually
he was radically "gothic". He probably (and many of his admirers)
would be outraged and offended by this judgement because he thought
that "gothic" architects were "barbarians". The
difference between him and the "gothic" master-builders is
that he tried to refer to the "roman" architecture and to
reproduce the paradigm of ancient Roman monumental buildings, domes
and vaults, whereas the Gothic had other references. But the procedure
of Brunelleschi was purely intuitive: he had no rational understanding
of his concepts.
He had an exceptional structural sensitivity, but he was basically guessing
and hoping for the best: for the construction concept of the Dome of
Santa Maria del Fiore he guessed correctly!
all my assumptions on Brunelleschi's structural conception are based
on prof. Ricci's researches and studies.
1296 The first stone of the new cathedral Santa Maria del Fiore chief
architect Arnolfo di Cambio (the same that had built Palazzo Vecchio)
1302 Arnolfo di Cambio dies in Florence
1348 the first Plague epidemics (Black Death) hits Florence 30%-25%
of the population succumbs
1363, 1374, 1383, and 1390 subsequent plague epidemics of lesser importance
1366 Giovanni di Lapo Ghini master of the construction proposes a
model for the dome
1367 Neri di Fioravanti is asked for a new model of the dome
1368 the officials of the Opera del Duomo after much uncertainty chose
Neris model even if nobody knew how to build it
1377 Filippo Brunellleschi
is born in Florence to Ser Brunellesco di Lippo Lapi notary and Giuliana
1339 Giottos Bell-tower (Campanile di Giotto) beginning of construction
1359 Giottos Bell-tower (Campanile di Giotto) completed;
1389-1464 Cosimo de' Medici (Pater Patriae)
1398 Filippo Brunelleschi becomes "orafo" (goldsmith);
1400 new Black Death epidemics 12.000 Florentine succumb (1/5 of the
1402 Competition for the bronze doors of the Battistero Lorenzo Ghiberti
and Filippo Brunelleschi are both chosen: Brunelleschi resigns outraged
because he does not want to work with Ghiberti. Ghiberti was 24 and
Brunelleschi was 25 years old.
1402-1416 Brunelleschi and his friend Donatello in Rome
1418 the Opera del Duomo officials announced a prize of 200 golden
Florins for models presenting technical devices for the construction
of the octagonal dome;
1418 The Opera del Duomo choses Brunelleschis and Ghibertis
proposals for the dome and asks them to work together
1420 Giovanni da Prato an old professor of humanae litterae is nominated
to assist Ghiberti: Giovanni da Prato does not like Brunelleschi and
nags him continuously
1420 August 7th the works for the construction of the dome officially
1421 Brunelleschi designs the huge "crane" oxen operated
1427 Failure of the transport barge Il Badalone designed by B. for
the transportation of blocks of marble on the Arno River: the cargo
goes lost in the river after the barge capsizes.
1429 Cracks develop in the church main nave close to the octagonal
base of the dome: fear of the worst slowed the construction process
for several years;
1430 Great botched attempt to flood Lucca with a dam on the river
Serchio Brunelleschi is responsible for the failure and suffers for
the heavy criticism;
1432 A first model for the lantern by Brunelleschi is presented to
the Opera dedl Duomo;
1435 last timber chain set on the summit of the dome;
1436 March 25th, for the celebration of the "Marys Announcement"
the Church of Santa Maria del Fiore is consecrated by the Pope Eugenio
IV with the dome "almost" finished. (lacking the last round
of bricks, the "lantern" on the top and the roof tiles)
1446 15th of April Filippo Brunelleschi dies
1449-1492 Lorenzo d' Medici detto Il Magnifico
1452 the lantern is completed as
designed by Brunelleschi and modified by Antonio di Ciaccheri, the
big bronze sphere (2.5 m of diameter) on top of the lantern is the
work of Andrea del Verrocchio in whose shop the young Leonardo da
Vinci worked as an assistant.
Alberti, Leon Battista; Dieci libri sullarchitettura,
Gela, Edizioni Librarie Siciliane, 1993;
Battisti, Eugenio; Brunelleschi: lopera completa, Milano,
Ghiberti Lorenzo; I Commentarii, Firenze, Giunti, 1998;
Mainstone, Rowland; Brunelleschis Dome, Architectural
Review, September, 1977;
Manetti, Antonio di Tuccio; Vita di Ser Filippo Brunelleschi,
Firenze, Rinascimento del Libro, 1928;
Prager Frank D., Scaglia, Gustina; Brunelleschi studies of
his technologies and inventions, 1970;
Ricci, Massimo, Il fiore di Santa
Maria del Fiore, Firenze, Alinea, 1983;
Ricci, Massimo, L'accusa di Giovanni di Gherardo Gherardi a
Filippo Brunelleschi, Firenze, Salimbeni, 1985;
Ricci, Massimo, in Le Scienze n.227, Il segreto della Cupola
di Santa Maria del Fiore, 1988;
Ricci, Massimo, Bollettino degli Ingegneri della Toscana n.
1-2 2001, La Cupola di Santa Maria del Fiore e il suo modello a grande
scala: verifica operativa di una ipotesi sul metodo di costruzione
Ricci, Massimo; <http://www.vps.it/propart/mricci.htm>
Vasari, Giorgio; Le Vite de piu eccellenti architetti,
pittori, et scultori, da Cimabue insino a giorni nostri, nelledizione
per i tipi di Lorenzo Torrentino, Firenze, 1550;
(***) What I attempt here is a drastic
simplification of a very complex problem: just to allow the lay reader
to grasp the core concept. Those interested can further their information
through the bibliography with specific attention to prof. Ricci studies.
(1) Golden Gate Bridge
San Francisco, Builder and Chief Engineer was Joseph B(aermann) Strauss
born in Cincinnati Ohio (January, 09, 1870) died in Los Angeles in 1938
(May 16th) (one year after completion of the Bridge);
Empire State Building New York: built in 1930-31 (in one year and 45
days 7 million man hrs) Shreve, Lamb, & Harmon Associates were the
architects for the building and Starrett Brothers and Ekin were the
general contractors. Six workers were killed during the construction:
Giuseppe Tedeschi, Laborer, 1/31/30; L. DeDominici, Laborer, 1/31/30;
Reuben Brown, Ironworker, 4/29/30; Sigus Andreasen, Carpenter, 7/14/30;
Frank Sullivan, Carpenter, 7/30/30; A. Carlson, Carpenter, 12/9/30;
Grand Coulee Dam: on the Columbia River in the State of Washington,
the largest concrete structure in the US, first proposed by William
M. Clapp attorney in Ephrata in 1917, Designed by the US Bureau of Reclamation
and US Corp of Engineers, initial excavation 1935 finished in 1941.
Galleria Vittorio Emanuele in Milan: Giuseppe Mengoni architetto 1829-1877
The Goldfields Water Pipeline: Charles Yelverton O'Connor who left Ireland
in 1865 to escape the potato famine. The Eastern Goldfields Water Pipeline
was completed at the turn of the century, but C.Y. OConnor shot
himself not bearing the criticism to the scheme that was to be proven
The Suez Canal and Panama Canal: were conceived and designed by Count
Ferdinand de Lesseps M.
(2) This is Rowland Mainstone
assumption utterly contradicted by the findings by Massimo Ricci;
many sleepless nights
(3) The exchanges
of poisonous sonnets and accusations between Giovanni and Filippo
supplies a thick chunk of literature;
(4) To visit the model
of the Cupola built by prof. Massimo Ricci his contact n. is 0011389055
473035 his e.mail Massimo Ricci firstname.lastname@example.org;