From: utzoo!decvax!duke!harpo!utah-cs!utah-gr!thomas Newsgroups: net.physics Title: Re: perpetual motion puzzle? Article-I.D.: utah-gr.686 Posted: Sun Jan 16 22:00:49 1983 Received: Wed Jan 19 04:24:20 1983 References: fortune.726 Yeah, it's easy - the pieces of plastic have gear teeth around the edge, and are rotated at the correct rates. (I.e., there is one piece of plastic for each hand.) =Spencer