Monday, April 28, 2008
Florence: the challenge of the dome on the cathedral
The complex history of Santa Maria del Fiore need not be recounted except to state that by 1418 all that was left to finish was the dome. The problem was that when the building was designed in the previous century, no one had any idea about how such a dome was to be built, given that it was to be even larger than the Pantheon's dome in Rome and that no dome of that size had been built since Antiquity.
Because buttresses were forbidden by the city fathers, and clearly was impossible to obtain rafters for scaffolding long and strong enough (and in sufficient quantity) for the task, it was unclear how a dome of that size could be built, or just avoid collapse. It must be considered also that the stresses of compression were not clearly understood at the time, and the mortars used in the periods would only set after several days, keeping the strain on the scaffolding for a very long time.
In 1419, the Arte della Lana, the wool merchant’s guild, held a competition to solve the problem. The two main competitors were Ghiberti and Brunelleschi, with Brunelleschi winning and receiving the commission.
The dome, the lantern (built: 1436-ca.1450) and the exedrae (built: 1439-1445) would occupy most of Brunelleschi’s life. Brunelleschi's success can be attributed to no small degree to his technical and mathematical genius. Thus he invented a new hoisting machine for raising the masonry needed for the dome, a task no doubt inspired by republication of the seminal work De Architectura by Vitruvius, which describes Roman machines used in the first century AD to build large structures such as the Pantheon and the Baths of Diocletian, structures still standing which he would have seen for himself. He also issued one of the first patents for the hoist in an attempt to prevent theft of his ideas.