Puzzle Time.

Wonderful day out today. Took the scooter out and off with us to the former home and studio of Finnish sculptor Emil Wikstrom. A feast of sheer pleasure for the eye but what is this? 
Seen in the kitchen and attached to a table, do not be misled by the piece of string which is only there to stop nasty little boys like me from turning the handle. I couldn't figure out what it was for but then I read the notice. I will share with you what it revealed tomorrow