JF Ptak Science Books   [Quick Post in the History of Lines series]

“That was when I saw the Pendulum. The sphere, hanging from a long wire set into the ceiling of the choir, swayed back and forth with isochronal majesty.. .The time it took the sphere to swing from end to end was determined by an arcane conspiracy between the most timeless of measures: the singularity of the point of suspension, the duality of the plane’s dimensions, the triadic beginning ofn, the secret quadratic nature of the root, and the unnumbered perfection of the circle itself… Were its tip to graze, as it had in the past, a layer of damp sand spread on the floor of the choir, each swing would make a light furrow…”–Umberto Eco, Foucault’s Pendulum.

I’ve uploaded an interesting recrod to the books for sale section of this blog on the great experiment of Leon Foucault (1819-1868), who was the first to actually demonstrate the rotation of the Earth, doing so with a very simple, extraordinarily elegant experiment involving a heavy brass bob suspended from a long cable–a pendulum that was unencumbered and free to swing along any plane.  It is the curvature of the Earth that allows the tip of the bob to make its pattern, and it is the fact that the Earth is rotating under the moving pendulum that allows it to be tracing this path at all–it is also tells the difference between living on a sphere and living on a plane.