Saving Michelangelo’s Dome: How Three Mathematicians and a Pope Sparked an Architectural Revolution

In 1742, Pope Benedict XIV was notified by the Vatican’s architect that St. Peter’s Basilica was cracking and that no one knew how to fix it, notes structural engineer Kalayjian in his meticulous and illuminating debut account. Designed by Michelangelo in 1549, the Basilica, standing at over 25 stories and weighing 33,000 tons, was composed of three main pieces: a drum upon which the dome sat, the dome itself, and a capped lantern. Michelangelo died with only the drum completed, and over the next 120 years a variety of builders completed the project, all implementing different techniques to raise the troublesome dome. Determined to save the structure, Benedict XIV, whose respect for modern science was unprecedented among previous popes, called for three of Italy’s most notable mathematicians—Roger Joseph Boscovich, Francois Jacquier, and Thomas Le Seur—to inspect the dome and publish a report utilizing new theories in calculus, statics, equilibrium, mechanics, and material science. Disparaged by the era’s architects, their findings were not part of the official plan for repairs but were ultimately implemented by the builders to save the dome from collapse. Kalayjian’s narrative propulsively blends a chronicle of one of the world’s most famous architectural achievements with the story of the birth of modern engineering. Readers interested in the history of science should take note. (Mar.)