The stone floor is where the two pairs of underdrift French Burr millstones are located . The stones are 4 feet 4 inches ( 1 @.@ 32 m ) and 4 feet 7 inches ( 1 @.@ 40 m ) diameter . The wooden crown wheel is located towards the ceiling . This drives the sack hoist on the bin floor . Other machinery on this floor are an oat crusher and a flour dresser .