Contrary Hinged-Dasher Air-Pump Churn: Two Crossing Dashers Fold to Gather, a Pump Blows Air Through the Cream

"I thus hinge the outer parts of the dashers to their central parts in order that after the butter has been produced from the milk or cream by turning the dashers in the directions pointed by the arrows x, x', the person who is churning may then, by simply turning the crank-shaft, I, and dashers, B, B', in the opposite direction, instantly lessen the extent of the space passed over or occupied by the dashers and thus increase the capacity of the churn or give room in the vessel, G, for the gathering of the butter into a mass"

Fit a brass spigot low in the side of a large pot at least 400 mm across, as the cock s. Stand the three printed feet in it and the stockpot on them, so water can lie under the stockpot's bottom and up its sides. Drill the stockpot's handle for the clamp hook m.

Cut a hardwood cover 350 mm across, bored 13 mm at 55 mm either side of its middle for the dasher axes k, k', 10 mm for the thermometer and 12 mm for the air tube. Screw two posts 40 x 20 mm, 110 mm tall, on it 300 mm apart and bore them 12.8 mm 80 mm above the cover for the crank shaft I, 12 mm stainless, 442 mm long, with a crank and handle on one end. Fit the two bevel sets so the wheels on k and k' are driven from opposite sides by the pinions on I, back to back between them: the dashers then turn opposite ways at the same speed. Hold the axes in the cover with shaft collars.

From 2 mm stainless sheet cut two centre parts 50 x 220 mm and four leaves 65 x 220 mm. Fix a centre part to each axis k, k', 50 mm above the vessel's floor, and hang a leaf on each of its long edges with two small butt hinges, set so the leaves stop in line with the centre part one way and fold back the other. Set the two dashers a quarter turn apart.

Fix the eccentric on the crank shaft outside one post, and a 100 ml syringe upright beside it, its plunger joined to a strap round the eccentric. On its nozzle fit two check valves on a tee, one letting air in, the other out. Run silicone tube from the outlet to a stainless tube that passes down through the cover and along the vessel's side to 8 mm above its floor, its end turned inwards.

Fill the reservoir with warm or cold water until the cream will sit at about 15 °C. Pour about 12 litres of heavy cream into the stockpot, set the cover with the dashers in, hook it down, and put the thermometer through it. Turn the crank so the leaves stand open, timing it, while the pump bubbles air in at the bottom. When the butter comes, turn the crank the other way: the leaves fold back and the dashers gather the butter. Lift the cover and dashers out, gather the butter, empty the reservoir by the spigot, drain the buttermilk, wash the butter in cold water until it runs clear, salt and weigh it.

**Philip L. Clow** of Cohoes, Albany County, New York, US 26,092, 15 November 1859, "Churn". He claimed the outer parts of the two contrarily revolving dashers hung to the central parts by hinges d, and the arrangement of the air-pump E and water-reservoir F with the revolving dashers and cream vessel. The patent gives no sizes; every size here is ours. His force-pump is not described inside: ours is a syringe with two check valves on an eccentric. His reservoir is a closed chamber under the vessel with a funnel, air-vent and cock; ours is an open pot of water with a spigot. His rubber packing between the pinions is left out.