Foucault's Pendulum

Proof (if you needed it) that the earth rotates 
can be found right here in the Musée
des Arts et Métiers, in Paris.  (I was taking it
on faith because the explanation is a
bit over my head.  So I'm glad I saw Foucault's
pendulum in action.)

[To see more Weekend Reflections,
visit James's meme.]