My guess is that they are pulleys, and they just happen to be stored encircling the chimney because it looked pretty. There are two more attached to the ceiling that look to be in a position to actually be used for maneuvering heavy materials and equipment.
What are the little roller thingys around the top for?
Not sure. Something for adjusting airflow or something, maybe? I don’t know much about traditional (or modern, for that matter) blacksmithing.
They look like pulleys.
My guess is that they are pulleys, and they just happen to be stored encircling the chimney because it looked pretty. There are two more attached to the ceiling that look to be in a position to actually be used for maneuvering heavy materials and equipment.