Through the use of various primary and secondary sources, students in this lesson will identify, understand and be able to explain why building the dome on Florence’s Duomo presented such a daunting task and Filippo Brunelleschi’s mathematical and engineering solutions to the problems. In an alternate and separate in-class activity, students will also try to replicate Brunelleschi’s dome using man-made materials (sugar cubes and play-doh) to understand the challenges of such an undertaking.
The great cathedral had lain unfinished for over four decades. In 1418, with the Medici family poised to exert its financial and political control over Florence, the Florentine City Council announced a call for proposals on how to finish it. The Basilica di Santa Maria del Fiore stood in the center of the city, towering over the countryside. Originally designed by Tuscan artist and architect Arnolfo di Cambio, the cathedral began as a gothic style church in 1296. Over the next hundred years, architects, masons and laborers worked on the great duomo. By the beginning of the 15th century, all that remained was to cap the enormous church’s altar area. That is when work ground to a halt. The problem was that, in 1400, no one knew how to build a dome big enough to cover the space, yet light enough not to collapse under its own weight. Year after year went by. Finally in 1418, an architect stepped forward with radical, untested ideas. His name was Filippo Brunelleschi.
According to Italian historian Giorgio Vasari in his 1550 book, Lives of the Most Excellent Painters, Sculptors, and Architects from Cimabue to Our Times, Brunelleschi won the competition by using a simple trick with an egg. When the city leaders questioned Brunelleschi on his design principles, he instead handed them an egg and challenged them to stand it on end. According to Vasari,
That whosoever could make an egg stand upright on a flat piece of marble should build the cupola, since thus each man's intellect would be discerned. Taking an egg, therefore, all those Masters sought to make it stand upright, but not one could find a way. Whereupon Filippo, being told to make it stand, took it graciously, and, giving one end of it a blow on the flat piece of marble, made it stand upright. The craftsmen protested that they could have done the same; but Filippo answered, laughing, that they could also have raised the cupola, if they had seen the model or the design. And so it was resolved that he should be commissioned to carry out this work.
Brunelleschi got the job. It would take over 15 years to complete the great dome. The technical challenge was immense. Except for the Pantheon in Rome (built in the 2nd century), no domes had survived the fall of antiquity. By the late medieval period, no one remembered nor understood dome construction, and yet Brunelleschi’s design solved complex mathematical and engineering issues. First, he came up with the idea of a double shell for the dome, with a series of vertical “ribs” supporting the structure. To prevent the dome from collapsing under its own weight, a series of stone and iron chains (still in place today) would be embedded into the inner dome to provide support and stability. For the outer shell, Brunelleschi used a herringbone brick pattern to transfer the weight of the newly laid bricks to the vertical ribs and then down to the cathedral’s base.
The dome was almost completed by the time Brunelleschi died in 1446. The cathedral was finally topped with a stone lantern structure in 1461 and the conical roof was crowned by a copper ball and cross, designed and built by Verrocchio in 1469. Perhaps providentially, in Verrocchio’s workshop a young apprentice named Leonardo di ser Pieto (known better today as Leonardo da Vinci) helped with the ball’s design and installation, remarking years later that he was impressed and awed by Brunelleschi’s use of machines and engineering techniques at the Duomo.
Through the use of various primary and secondary sources, students in this lesson will identify, understand and be able to explain why building the dome on Florence’s Duomo presented such a daunting task, and Filippo Brunelleschi’s mathematical and engineering solutions to the problems. In an alternate and separate in-class activity, students will also try to replicate Brunelleschi’s dome using man-made materials (sugar cubes and play-doh) to understand the challenges of such an undertaking.
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While on tour, students in Florence will visit the Basilica di Santa Maria del Fiore, commonly known simply as the “Duomo” (Italian for “cathedral), where they can see for themselves Brunelleschi’s amazing dome. The Duomo dominates the Florentine landscape today, over 500 years after it was finished. They will have the opportunity to tour the duomo itself and explore the dome. Brunelleschi is buried in the crypt below the church. At the entrance to the cathedral is the following epitaph: "Both the magnificent dome of this famous church and many other devices invented by Filippo the architect, bear witness to his superb skill. Therefore, in tribute to his exceptional talents, a grateful country that will always remember buries him here in the soil below."
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