Free Brunelleschis Dome by Ross King Page B

these courses might be held in place without centering of some sort.
    Both Filippo and the wardens seemed to be purchasing themselves a little time by deferring the central question of how the dome should be vaulted. All were agreed that, in an unprecedented structure like the dome, any constructional difficulties could be solved, as the 1420 program stated, only by means of “practical experience.” This was perhaps to err on the side of optimism. But just such a process of trial and error was about to begin.

S OME U NHEARD-OF M ACHINE
I am accustomed, most of all at night, when the agitation of my soul fills me with cares, and I seek relief from these bitter worries and sad thoughts, to think about and construct in my mind some unheard-of machine to move and carry weights, making it possible to create great and wonderful things.
    T HESE WORDS ARE SPOKEN by the statesman Agnolo Pandolfini in a philosophical treatise written by one of Filippo’s ablest disciples, the architect and philosopher Leon Battista Alberti. Della tranquillità dell’animo (On the tranquillity of the soul) was composed in 1441, a few years after Filippo’s dome had been completed. It features a dialogue between two men who have suffered miserably from changes in fortune: Agnolo, who has retired, disillusioned, from public life, and a younger man, Nicola de’ Medici, whose bank has failed, leaving him destitute. Their conversation takes place inside Santa Maria del Fiore, under the new dome, and concerns the various means of overcoming depression. Agnolo lists a number of traditional remedies for raising the spirits, such as wine, music, women, and sports. But his most effective tactic, he tells Nicola, is to fantasize about the construction of giant hoists and cranes that can be used to create “great and wonderful things” — machines for raising magnificent structures, that is, like the dome that swells above them.
    One of the most obvious problems in building the dome of Santa Maria del Fiore — or indeed any large structure — was how to transport heavy building materials such as sandstone beams and slabs of marble several hundred feet above the ground and then place them into position with the accuracy demanded by Filippo’s design. The sandstone beams weighed some 1,700 pounds each, and hundreds of them needed to be raised onto the cupola. To solve this problem Filippo was compelled to imagine “some unheard-of machine” to move and carry tremendous weights to incredible heights. The hoist that he created was to become one of the most celebrated machines of the Renaissance, a device that would be studied and sketched by numerous other architects and engineers, including Leonardo da Vinci. And it was also, no doubt, the inspiration behind Agnolo’s soothing fantasies.
    A number of machines were already in use on the building site, of course. Twenty years earlier a rota magna , or “great wheel,” had been constructed to raise the heavy stones used in the facade, drum, and tribunes of the cathedral. This machine, still operational in 1420,was a treadmill that winched loads aloft under the motive power of several men who walked around, hamsterlike, inside a large wheel. Such devices had been in use since ancient times. In De architectura the Roman architect Vitruvius describes a treadmill turned by “tramping men,” presumably slaves. The treadwheel, a sort of giant spool, either wound or unwound a rope that, in passing through a system of pulleys, raised or lowered the weight attached to its end. The muscular effort involved in powering these winches was not excessive, provided the loads were relatively light and the heights to which they were transported not especially high.
    Recognizing that the rota magna would be woefully inadequate to the task of lifting heavy stones to the height required by the dome, the Opera del Duomo had specifically called for models of lifting devices in the 1418 competition. But the models submitted