Huygens' Clock Puzzle Solved

PhotoGuy writes "Okay, I haven't heard of this puzzle either until now, but it sounds like a fascinating phenomenon. According to this article:Huygens had two clocks side by side and he found that even when they began out of sync, they soon got into a rhythm where the pendulum on one moved as if it were a mirror image of the other.The article is pretty light on the explanation, noting only the conditions required (small relative mass of the pendulums [pendula?], relatively close speed of the clocks), and not really addressing the physics behind it. " There's a great site at Georgia Tech that explains the puzzle in more detail.