hub question

In school I am working on a science project about a unicycle. Could some one explain to me how the gears on a geared hub work, or give me a link to a site that will tell me? Also, does anyone have any diagrams.
Thanks Alot!

here is harper’s site:

here’s another one with a similar design

The best description I have seen of the operation of an epicyclic hub is on the Sturmey-Archer website. I have a link to it on my web site which Handy-Andy referenced. I tried the Sturmey-Archer website today and it seems sleepy or dead. Perhaps it’s temporary.

This is the link to the S-A website

It has a little cartoon of the internal hub and a description of what is going on as everything moves.

Thanks alot. I got it.