Brunelleschi: Studies of His Technology and Inventions

Brunelleschi: Studies of His Technology and Inventions

by Frank D. Prager, Gustina Scaglia

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A pioneer of Italian Renaissance architecture, Filippo Brunelleschi is most famous for his daring and original ideas, among them the magnificent dome of Florence's famed Santa Maria del Fiore cathedral. This comprehensive book describes how he created the structure, construction concepts, and other inventions. 28 halftones, 18 line illustrations.


A pioneer of Italian Renaissance architecture, Filippo Brunelleschi is most famous for his daring and original ideas, among them the magnificent dome of Florence's famed Santa Maria del Fiore cathedral. This comprehensive book describes how he created the structure, construction concepts, and other inventions. 28 halftones, 18 line illustrations.

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Studies of his Technology and Inventions

By Frank D. Prager, Gustina Scaglia

Dover Publications, Inc.

Copyright © 1970 The Massachusetts Institute of Technology
All rights reserved.
ISBN: 978-0-486-15728-3



1 In his own day, Filippo Brunelleschi (Florence, 1377-1446) became known as the man who "renewed Roman masonry work." This renewal is now identified with the architectural Renaissance. The sober-minded Florentines appreciated its "economy" as well as its "harmonious proportions," and they said its economy came from the introduction of "vaulting without armature." Such was the view of Filippo's chief employer, the cathedral-building office of the guild of woolen manufacturers, and also the view of his first biographer, the humanist Manetti. More or less the same view recurs in an early expression of Alberti, a man outstanding among those who developed the Brunelleschian style:

Who is so dull or jealous that he would not admire Filippo the architect, in the face of this gigantic building, rising above the vaults of heaven, wide enough to receive in its shade all the people of Tuscany, and built without the aid of any trusswork or mass of timber....

It is odd to see the work of the famous renewer equated with nothing more than a money-saving expedient. It seems more plausible to read in Vasari, the author of the classic Life of Brunelleschi, that the master created a new possibility, not only a saving of cost. The builders in Florence were worried, Vasari says, "that no way could ever be found ... to make a bridge strong enough to sustain the weight." Filippo overwhelmed them by showing that one could build "so great an edifice" without this "bridge," not merely with a cheaper bridge. Vasari agrees with Manetti that it was the master's wish "to restore to light the good manner of architecture" and that he achieved this, thereby establishing "no less a name for himself than Cimabue and Giotto had done."

Very different are the views prevailing today, which we will show and discuss throughout these studies. When all the evidence is considered, old Vasari may still be right in many respects. Modern archivists have discovered documents that disagree in some points with the biographers' views. They show that hero worship had been practiced. It does not follow that the biographers' views are totally wrong or that, for example, the innovations claimed for Filippo were anticipated in the Trecento. We will cite and consider such authentic evidence as we can find. Of course we will also note the explanations suggested by biographers and other reviewers.


Even before Filippo's birth a controversy about the Florentine cathedral had come before his father, Ser Brunellesco di Lippo Lapi, and even before the time of Ser Brunellesco there had been major architectural debates relating to Santa Reparata, the older metropolitan church.

This church, which also served as a meeting place for popular referenda, had been founded at the approximate location of the present Duomo in or about the seventh century. Six centuries later, near the end of the feudal period, it was badly in need of reconstruction. In 1282, the city adopted a government of Major and Minor Guilds, and ten years later Arnolfo di Cambio, an architect of considerable repute in Rome and elsewhere, was hired to build foundations for a new front, new and wider walls, and new and higher piers, reaching to a level above the old basilica. It was also proposed—either then or perhaps during the next few generations, which included the times of Giotto—that the new cathedral would no longer terminate with small semicircular apses, as the original one, but with an enormous cupola structure.

The middle decades of the Trecento were one of the most miserable times that visited Florence and Europe, a time dominated by war, civil war, plague, famine, and insane movements. The Guild republics faltered badly. The Ghibelline Visconti and the Anjou, tyrants of Milan and Naples, respectively, were ascendant. Their political success had effects on Italian building styles. The Milanese court, full of Germans, as well as the southern court, usually full of French, attracted French and German followers, including Gothic builders, into Romanesque Italy. Their influx accelerated a movement that had begun already under Imperial and monastic influences in earlier times —the evolution of an international style containing many northern motifs and methods.

Major segments of the Florentine population hated the foreign influx with a passion. A movement took place that contained a variety of Guelph, Roman, and Humanist components; it may also be described more simply as an anti-Gothic or conservative movement. In Trecento sculpture it brought strong renewals of classic Roman forms. In Trecento architecture it brought emphatic reassertions of Romanesque traditions.

It is unknown whether Arnolfo had planned a Gothic or a Romanesque form for a Florentine Cupola (see Figure 2). It is also unknown in part how he would have constructed its fabric and ornamented its surface. Some buildings in Gothic form had been built in Italy, but Italians were more familiar with the Romanesque traditions. There were flat-profiled Roman cupolas, comprising an interior cap or calotta, hidden entirely or in part behind an outer wall. A totally hidden cupola was to be found in the Florentine Battistero. Whatever Arnolfo may have planned, this was the kind of cupola known and revered in Florence during the Trecento.

Work on the Florentine cathedral was restarted after the Black Death, about 1350. It still was unclear whether the cupola would be Gothic and pointed, or semicircular (Figure 3). However, while continuing to cover the walls with the usual geometric-polychrome, marble incrustation, the builders had begun to add Gothic windows and niches. The developing plans gave rise to power struggles. In 1361, the Woolen Guild announced that its Opera would no longer appoint officers or masters without consent of the Guild Consuls, because "workers must not be defrauded."

Debates about the cathedral construction then dealt mainly with the reinforcements required by the large vaults, and their aesthetic effects. The capomaestri, Francesco Talenti and Giovanni Ghini, wanted a Gothic church with outer, reinforcing buttresses. Various advisers disliked this un-Roman kind of building and probably its Ghibelline associations. The position of some artists was complex. Orcagna in his so-called Tabernacle—the monument in Or San Michele, full of pictures, sculptures, and marble embroidery, reaching up to the ceiling-ornamented the top with a cupola on a tambour with circular windows. This feature alone is similar in outline to the now existing Dome, but an entirely different effect is produced by the surrounding four and higher pinnacles of Gothic form and ornamentation. Even without the pinnacles Orcagna's dome form does not suggest technical possibilities for the construction of an unusually large vault. It shows one variant of Florentine-Gothic design, without an attempt to show Gothic or other structure.

The official debates of the time did not deal with the form or anatomy of a cupola structure. They dealt with the design of windows for the nave, which Ghini was finishing, and with proposed dimensions for the foundations of the cupola-supporting octagon at the end of the nave. Talenti had proposed that this octagon should have an inside width of 62 braccia (about 120 feet), but Ghini would have increased this size, apparently even beyond the present 72 braccia (about 140 feet). A chronicler wrote of a cupola almost as high as the actual one.

For Talenti and Ghini it was obvious that the walls of the octagon would have the strong outer buttresses or counterforts of Gothic tradition. In keeping with such tradition, Ghini proposed that the walls themselves be made rather thin, thereby providing a maximum of church space within the inside boundaries of these walls. The outer boundary of the octagon was substantially given by the existing nave structure.

A different view was taken by a group of artists officially consulted by the Opera, who had as their leader the architect Neri di Fioravante. Neri and his committee did not want buttresses. For this reason, and since the possibilities of using inner ribs were limited, these men needed stronger and thicker walls for their octagon. Their inside octagonal area became smaller than it was in Ghini's design, as the outside boundary could not be made larger in view of structures already existing. Some of the cardinal points for two of the large piers of the octagon (Figure 1, at "6") already were fixed by excavations and the beginnings of masonry work placed by Ghini.

Ghini asserted that the artists' plan would lead to a church with clear inside space smaller than his own. This was true. He also asserted that it made the structure weaker. This was very questionable.

The artists consistently denied that their plan was less strong than Ghini's. At one point, as we will see, they charged that Ghini misrepresented their plan. The negotiations were complex, although Ser Brunellesco, as a lawyer, may have understood them clearly. So much is certain that Ghini vociferously insisted on the use of tall buttresses as outer reinforcements for the nave. He strongly suggested the use of similar buttresses for the cupola structure. He also wanted tall Gothic windows. The artists firmly rejected this design.

The citizens of Florence favored the artists' view. In 1364, they decided that "in the wall above the minor [side aisle] vaults there shall be round openings, not [tall, narrow] windows to admit light through the walls of the large [nave] vaults, one opening in each vault." The existing "wall above the minor vaults" (Figure 11, directly below the roof of the nave) shows the actual use of the artists' ideas, while the lower outside walls show the design ideas of Arnolfo, Giotto, Talenti, and Ghini.

It hardly appears that the debates of the 1360s applied to any part of the octagon structure except its foundations, such as a drum or tambour for this structure. No tambour is mentioned in the documents of the time, although Orcagna—a member of the artists' committee—shows a tambour in his Tabernacle, as mentioned. The debates dealt with the superstructure of the nave and the substructure of the octagon, and the decisions had to do with these structures exclusively, in keeping with the empiric step-by-step methods used by early builders.

Friction between Ghini and the artists was very evident in the summer of 1366, when Ghini was constructing the first two vaults of the new nave, near the entrance facade. There were no buttresses leaning against the vaults, and the old-timers were nervous when Ghini placed the masonry on his conventional centerings. They became very nervous when hairline cracks appeared (which unavoidably result from the shrinkage of the cement during the setting of the masonry). The artists were undismayed. They enforced exclusive reliance on tie rods, so-called chains. They also established themselves as a permanent supervisory committee. Tie rods as specified by the artists extend across the arches between the nave and the aisles. The rods are ugly as they cross the arches in odd locations.

As to tie members or other reinforcements for the octagon, the artists were hardly expected to have finished proposals, and they expressed only general ideas about this problem. In a report dated August 1366 they expressed their hope that someone would find some means to construct the cupola without visible chains or ties. Their report is silent about a tambour and about the height of the cupola. The artists' design was recorded on parchment sheets, as were the counterdesigns of Ghini and others.

For some time the outcome of these proposals was in balance, but dramatic proceedings that followed brought an end to the era of strong, Gothic influence. A civic committee decided in favor of the artists, and the Opera then ordered construction of a masonry model based on the artists' design. Ghini, as capomaestro, constructed it and also continued to build the nave of the church. In May 1367, Ghini obtained a hearing about alleged dangers for the cupola, inherent in the artists' design. A committee of other artists convened, which proceeded to express doubt in the structural soundness of Neri's plan. In July the questions came before a new body of civic advisers. It was then that Neri complained about Ghini's misrepresentation of the artists' design. Ghini apparently had shown the inside area very large, while leaving the outside boundary as required by the nave, and had omitted outer reinforcements as requested by the artists. Thus he had weakened the piers while adding to the vault pressures.

The new civic committee decided that the danger alleged by Ghini could be eliminated and that he should return to the basic inside dimensions, which the committee now specified in very emphatic terms. Ghini was to use them in producing a corrected model of the artists' design. He also was given a substantial loan. It seems that Ghini then relented. He built the corrected model, as well as the end of the nave, and there is no indication of further friction. The artists made a concession of their own: they allowed the use of triangular buttresses reinforcing the tribunes.

Ghini's model was then destroyed, while the artists' model, built by him, was definitely adopted. This model then remained in the aisle of the Dome near the Campanile. For some fifty years it stood near the area where the visitor now stands to see the monument to Brunelleschi. (See our frontispiece. The area at right of "5" in Figure 1 is its location.)

In October 1367, the city organized a large, new committee to make a final decision in the dispute between Gothic and Romanesque factions. The committee included several dozen members of Major and Minor Guilds who were selected, as usual, by lot from a hand-picked list. One member was Ser Brunellesco, who had just returned from a trip abroad as a lawyer in the service of Florence. Other noteworthy participants were Antonio Machiavelli and Jacopo degli Alberti, who may have been merchants. Jacopo stated that he found the artists' model more beautiful outside—no doubt because it omitted the Gothic appendages—and that Ghini's model seemed more beautiful inside, probably on the ground that Ghini more definitely than the artists omitted visible tie rods, spanning the vault in various directions. The committee expressed itself in favor of the artists. Then, as a final step, came a referendum of some five hundred citizens. It confirmed the conclusion, as referenda in Florence usually did.

Neri's committee had obtained this decision by being adamant in its rejection of Gothic vault structure, although some of the artists had sympathetic attitudes toward Gothic ornamentation. The committee had the support of numerous and influential Florentines. It was powerful enough to obtain disciplinary action, at various times, against masters who favored Gothic principles.

The committee's victory probably led to feelings of national and aesthetic satisfaction. However, the artists and their model left a large problem unsolved, which Filippo then inherited. This was the problem, how to overcome the dangers anticipated by Ghini, while omitting his buttresses. No one at the time, or for centuries thereafter, could solve such a problem theoretically. The record indicates that the artists did not even attempt to solve it. Their decision, like Arnolfo's original design, was aesthetically bold but structurally weak, and its weakness did not go unnoticed in later times.


The tangible result of the great debate was the artists' model, built by Ghini. It was later called a small model, by comparison with another structure. Probably it showed the then-existing building portions and the more or less clearly proposed additions on a scale of no more than about 1:16, that is, with little detail. Perhaps one could just barely enter the nave and see the interior. The documents do not indicate whether the model had any kind of cupola or tambour. They only state that it had three tribunes of five chapels each, and "certain walls" in their vicinity, probably meaning the buttresses contained in the compromise plan. The debate had made it clear, and the model probably confirmed, that with minor exception neither the superstructure of the nave nor the understructure of the octagon was to be Gothic.

This model was one of the prize possessions of Florence during the decades about 1400. Filippo must have seen it often, and since his father was able to describe its background history, Filippo soon must have learned how much the model left unanswered.


Excerpted from Brunelleschi by Frank D. Prager, Gustina Scaglia. Copyright © 1970 The Massachusetts Institute of Technology. Excerpted by permission of Dover Publications, Inc..
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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