This Parisian iron ball suspended and wire-swinging
inside the Panthéon dome proves that Earth
rotates on its axis, steady but relative
to our turning world. It’s physics –
but I take comfort in any constancy.
I learned more about Foucault’s pendulum in Umberto Eco’s novel by that name. It’s a high-level adventure that might remind you of Dan Bown’s popular novels. Some Milanese book editors create an elaborate hoax connecting the medieval Knights Templar with occult groups and making a map that shows the geographical point from which all the powers of the earth can be controlled. Spoiler: It’s in Paris at Foucault’s Pendulum.