Here are two diverse mechanisms I photographed recently. Can you tell what they are?
Yes of course. It's part of a bicycle. We know that because we have seen lots of them. Even this neglected example is readily recognisable with it's spokes and it's rust.
But what about this then? It looks like a fob watch with it's rear cover open. But surely no-one ever made a watch this crude. Where are all the jewels? Where's the delicate cog wheels and escapement?
Well, this is the workings of a hundred year old Pedometer, which is a thing that measures feet, as far as I can tell.