Ice-Chamber Air Churn: The Hollow Dasher Pumps the Same Air Round Through Ice and Cream

"At every upward movement of the staff F, the air from the chamber C, rushes down within the staff F, into the chamber d ... and as the dasher descends the valve e, closes and the air within will be forced into the cream j, and at the same time the air in the case above the cream will be compressed by the rising of the cream j ... and said air will pass up the space f, into the chamber C".

Use a food-grade 20-litre bucket and its lid (lid B), and a round food container 200 mm across and 130 mm deep as chamber C, its own lid as lid D. Cut a 40 mm hole in the middle of lid B and of the container's floor. Push tube E up from under lid B, set the container on the lid and the clamp ring over the tube, and fix them with four M4 screws and lock nuts. Cut a 30 mm hole in the middle of lid D.

Bolt box a on top of lid D and box a' under it through their flanges, three M4 screws, the notches of a' against the lid. Cut the stainless tube (16 mm, 1 mm wall) to 549 mm. Drill two 5 mm holes c straight through it, crossed, 389 mm from its foot, and a 4.4 mm hole across it 6 mm and 534 mm from its foot for the cross screws.

Hang the flap e on the lug in the dasher's chamber with an M3 screw and lock nut so it covers the air hole from below and swings down freely. Push the staff's foot 12 mm into the dasher's top and fix it with an M4 screw across.

Cut a hardwood foot 90 x 34 x 30 mm and bolt it to lid B 120 mm from the middle, with two M6 bolts through a hardwood backing strip under the lid. Screw a hardwood upright 30 x 45 mm, 337 mm tall, on it. Cut two lever strips 30 x 12 mm, 480 mm long; drill each 20 mm from one end for pin g and cut a 6.5 mm slot from 110 to 135 mm past it for pin h. Lower the staff through tube E and the boxes, push on the staff head with an M4 screw across, and bolt the strips either side of the upright (pin g) and of the head (pin h) with M6 bolts, washers and lock nuts.

Pour 8 litres of heavy cream at about 15 °C into the bucket, checked with the thermometer. Fit lid B with the dasher in place, fill chamber C with crushed ice round tube E and close lid D. Work the lever up and down steadily, the full 100 mm stroke, and time it. When the butter comes, lift the lid out, pour off the buttermilk, wash the butter in cold water until it runs clear, work in a pinch of salt and weigh it.

**James H. Bump** of Morris, Otsego County, New York, US 21,871, 26 October 1858, "Churn". He held that the cream, "by the absorption of oxygen is fully acetified" and kept cool by the iced air, gives butter "of a superior quality". He disclaimed a hollow dasher rod for air and forcing air into cream as done before, and claimed only the chamber C through which the air is made to circulate. He gave no sizes and named only "metal boxes": every size, material and the 8 litres at 15 °C are ours. Our notches in box a' stand in for his grooves cut in lid D.