A Foucault pendulum shows the rotation of the earth. It swings back and forth in the same plane, but the earth's rotation makes the pendulum appear to change its path gradually.
<BR><P>
World Book photo by Dan Miller</P>
</BODY></P>
<!-- <PT>YES -->
<!-- <AR>From The World Book Multimedia Encyclopedia (TM) (c) «date» World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved. -->