Most of you probably remember reading about a wonderful astronomical clockwork mechanism found in a sunken ship dating back to 200 BC ------- not our BC :-)
Here is a link to a more detailed explanation of how it worked and how it might have looked. If you go to the bottom of the web page you will find a video of a reproduction made from Lego parts. It shows the inner workings in nice detail. It also discusses the gearing necessary to follow the 19 year eclipse cycle.