Watermill (and how it works)

Today, we went to Henley and spent a bit of time at the River & Rowing Museum. Small museum, but it has some very interesting sections and it's a great place to keep a child entertained. It is also a nice place for an adult who never really completely grew up, like me. I saw many very fascinating things there, among them this watermill model. I am not very technical, but thought it was really well done, explaining in layman's terms how thw watermill works. I also loved the attention to details: there is a cat and a mouse on this display, as there would be in a real watermill (the mouse eating the grain, the cat hunting the mice). Can you find them?