Trapped-Air Cylinder Dash Churn: A Hollow Dash That Squeezes Air Into the Cream

Murdock wanted the air carried down through the cream by the common up-and-down dash itself. Charles Murdock of Baltimore, Maryland, received US 6,133, dated 20 February 1849, for "Murdock's Atmospheric Churn": a hollow cylindrical dash, perforated round its lower open end, on the common dash staff, which is bored to slide over a fixed central spindle. The spindle stands in a stationary cylindrical block, smaller than the dash, held to the churn's bottom by a nut. At each stroke the dash fills with air above the cream, carries it down, and when it meets the block the air "is compressed in the cylinder forced radially through the apertures." This rung works out the air squeezed out each stroke, then prints the dash and block, fits them to a churn, and makes butter.