During the French Second Republic—the volatile period between the 1848 Revolution and Louis-Napoléon Bonaparte’s 1851 coup d’état—two striking performances fired the imaginations of Parisian audiences. The first, in 1849, was a return: after more than a decade, the master of the Parisian grand opera, Giacomo Meyerbeer, launched Le prophète, whose complex instrumentation and astounding visuals—including the unprecedented use of electric lighting—surpassed even his own previous innovations in sound and vision. The second, in 1851, was a debut: the installation of Foucault’s pendulum in the Panthéon. The installation marked the first public exposure of one of the most celebrated demonstrations in the history of science. A heavy copper ball suspended from the former cathedral’s copula, once set in motion, swung in a plane that slowly traced a circle on the marble floor, demonstrating the rotation of the earth.