A questioner said:

What is this dial with a chain that goes into the floor of this old house?

More info from questioner: An old house, not sure what year, but the dial can be turned and the chain moves but doesn’t change anything evident.

Some of the answers:

1. My grandmother’s house had these back in the day of the convection flow hot air furnaces. They operated dampers in the hot air ducts to control heat levels in the living spaces. I’m guessing that these are such damper controls.
2. Probably opened a vent for heat.
3. Damper for a coal furnace
4. Controlled the damper of a coal burning furnace
5. Itd be cool to see the other end…
6. So glad to see this. A little over 4 yrs ago I moved into the house that my grandfather grew up in. It has one of these, and I was never quite sure what it was.
7. I wonder if when that chain breaks if it’s as bad as when it happens on a huffy
8. If you find the other end of that chain, you’ll have your answer
9. My house has a mark on the wood and holes in the floor where one of these used to be. I’d love to find one to put back up.
10. Thats an old heat adjusterWould turn up the heat in the basement on a coal furnace or open a duct to allow more air to flowNow they are just wee little thermostats on the wall
11. Its to adjust the damper on an old furnace. We had an old wood burning furnace in our farmhouse.
12. Limber chains.
13. Yes, it is a damper but it opens or closes a door that allows more air into the fire pot. Increase or decreases the heat generated by the coal fire.
14. I love how everything eventually gets covered in paint!
15. The control for an old dumb waiter, perhaps.
16. It controlled the air flow into a coal furnace (damper). Open the damper, more air into furnace, coal burns faster/hotter. Close the damper, less air coal burns at a slower rate, cooler. Had coal furnace in house I grew up in.