Twin-Plunger Air-Chamber Churn: Two Plungers Throw the Cream Through a Middle Chamber

Andrews made the cream do the travelling, back and forth through a middle chamber. John Andrews of Middlesex County, Massachusetts, received US 7,298, dated 23 April 1850, for a churn box divided by two vertical partitions into three apartments, with a series of holes "at or near its bottom" in each partition, "unprovided with valves." Each outer chamber has a plunger on a rod jointed to a brake, "one of the said plungers being elevated while the other is being depressed," so the cream is thrown "back and forth in several streams through the air chamber." Holes near the partitions' tops let air in under each rising plunger. This rung works out the streams, then prints the partitions and plungers, builds the box and brake, and makes butter.