Using a handle, the owner of this small but pretty organ was playing at the Etruria Canal festival today. The birds on to of the organ sang and whistled too. They could work independently of the organ and it was good to hear their beautiful sound.
I think the mechanism must drive bellows that sends air down the different pipes of the organ. I didn’t look at the mechanism but it probably runs on cardboard/wood slats with holes and slots cut into them to hold the organ stops open for different lengths of time in order to play music. Presumably the music changes speed depending on how fast the handle is spun round.