Spiral-Corrugated Water-Jacket Churn: A Bevelled Strip Dasher Throws Cream Against Diagonal Corrugations in a Warmed or Cooled Chamber

"It is a very essential thing to force the cream against a surface which will break the direction of the current and at the same time allow the cream to flow back to the point from which is was moved, for by breaking the current, the churning is facilitated. Our diagonally or spirally corrugated churning chamber does this perfectly."

Glue up two hardwood ends 30 x 290 x 288 mm. On each, 160 mm above the bottom edge, draw circles 203 and 209 mm across and rout a groove 6 mm deep between them, with two straight grooves 4 mm wide rising from it to the top edge, about 125 mm apart between centres, for the lips. Cut hardwood sides 20 x 288 x 400, a bottom and a top 20 x 250 x 400, and cut a mouth 122 mm wide the length of the top. Seal the four rings end to end with silicone, set their ends and lips in the grooves with silicone, and glue and screw the case together round them, sealing every joint inside: the space round the chamber is the water jacket. Bore a 16 mm hole in the top 100 mm off centre and seal in a short stainless tube a for the water. In one end bore 16 mm holes at the chamber's bottom and at the case's bottom and fit rubber stoppers: drains for the buttermilk and the water (ours). Make a hardwood lid for the mouth with a plug that fits it.

Cut two hardwood end bars b 50 x 20 mm and 156 mm long, and bevel both ends of each across its width, from the full length on one edge to 100 mm on the other, the two bevels facing opposite ways. Cut six hardwood strips c 20 x 6 mm and 360 mm long, and screw three, one below another, along each pair of bevelled ends, so they stand on opposite sides of the shaft and run end to end across the corrugations. Bore the bars 16 mm at their middles, 360 mm apart over their outer faces, on a 16 mm stainless shaft D 515 mm long, and pin them. Pass the shaft through the ends at the chamber's centre, hold it with a shaft collar outside each end, and pin on a crank of mild steel flat bar, 120 mm throw, with a hardwood handle.

Pour about 5 litres of heavy cream into the chamber, so its surface stays below the shaft. Pour water through the tube a into the jacket, warm in a cold room or cold in a warm one but never hotter than the hand can bear, until the cream reads about 15 °C on the thermometer. Put on the lid and turn the crank steadily, timing it. When the butter comes, draw the buttermilk off by its stopper into a bowl, take out the butter through the mouth, wash it in cold water until it runs clear, salt and weigh it. Drain the jacket by its stopper.

**David Sherman** of Uniontown, Maryland, and **Robert W. Fenwick** of Washington, D.C., US 29,445, 31 July 1860, "Churn", assigned to D. Sherman and Bernard Mills. They claimed "corrugating the surface of the near cylindrical churning chamber diagonally or spirally ... in combination with the blades c, c, (of the dasher) which are set so as to stand across the diagonal or spiral corrugations". Their chamber was a bent, corrugated metal plate; ours is printed rings with plain outsides. The drains are ours; the text does not say how the buttermilk or water is let off. The patent gives no sizes; every size here is ours.