The controller for the drill that was used to punch a hole in the bottom of the furnace in order to release the molten iron.
 
 

Cast Room Controller

This photograph was taken in a room protected by metal walls. This is where the foreman would use a drill controlled by the device in the photo to open the furnace and drain the molten iron.

The audio segment also describes this, as well as how the furnace was closed again after it was drained in order to continue the process of iron production.