rotating underneath; and in a minute or two we shall see the effect of the earth moving.
[In Fig. 5 the pendulum bob was at first swinging from D to C; the shadow being thrown on the screen from the point X was near the middle of the screen most of the time, but as the pendulum bob reached the point C, the shadow fell at c, away to the right. Presently the earth's rotation altered the path of the bob to BA, and at A the shadow fell at a, away to the left.]
FIG. 5. FOUCAULT'S PENDULUM.
Magnification of the Effect.
You will see that as the pendulum comes up to the lamp the shadow will flash to the right, and it would go on doing that always if the earth did not move; but as the earth moves it will presently go to the left. There will be a moment when it will spread out on both sides; and after that it will go to the left. I hope we can manage the experiment without keeping you too long. Now I will burn the thread. There, you see it goes to the right, and presently it will go to the left. You remember when Peter Pan
