Inclined-Wheel Cam Dog Power: A Dog Turns a Tilted Platform; a Zig-Zag Cam Rocks the Churn Lever

"The dog is placed on the wheel G, and rotates it by the movement of his legs, and the cam H, as it rotates gives a vibrating motion to the lever I, from which the power is taken."

From 70 mm square timber lay sill A 1665 mm long and a front sill 1000 mm long across its end. Stand post B upright and post C beside it, 260 mm apart, on the front sill, and join their tops with bar D running back 660 mm over the shaft's top. Screw the printed step block on sill A 870 mm behind the front sill and bolt a flange bearing on it; bolt a second flange bearing under bar D so a line between the two leans 15 degrees toward the posts.

Halve two 70 mm timbers 1300 mm long into a cross for arms b, bore the crossing 30 mm and glue and screw two layers of 18 mm plywood cut to a 1400 mm disc on them as platform b'. Screw pine cleats on top for the dog's grip. Pass a 30 mm steel shaft 1335 mm long through the lower bearing, the wheel and the top bearing, and cross-bolt the wheel to it 250 mm above the step. The platform is square to the shaft, so it tilts 15 degrees.

Bolt the four cam segments round a hardwood hub on the shaft, 990 to 1150 mm above the step, so the groove runs unbroken round them. Screw two hardwood cheeks down from bar D as pendant E, about 190 mm in front of the cam's face, and drill them 12.5 mm for the fulcrum pin e. Cut a hardwood lever I 30 x 20 mm, 815 mm long, drilled for the pin 174 mm from its inner end. Fit a 28 mm printed or hardwood roller f on a 10 mm stainless stub through the inner end, set it in the groove and bolt the lever between the cheeks.

Stand a food-grade 20-litre bucket under the lever's outer end, 600 mm beyond the pin. Hang a 12 mm stainless rod 900 mm long from the lever's end on a bolt, through a slot in the bucket's lid, with a 220 mm dasher of plywood screwed to its foot so it works between about 95 and 340 mm above the floor. Put an eye bolt in post B for the dog's lead.

Use a harness, never a collar, on a lead to the eye bolt in post B, the dog standing on the platform facing up the slope. Start with short sessions and treats until it walks calmly. Pour about 9 litres of heavy cream at about 15 °C into the bucket, checked with the thermometer, put the lid on and let the dog walk; time it. When the butter comes, pour off the buttermilk, wash the butter in cold water until it runs clear, work in a pinch of salt and weigh it.

**Dexter C. Slater** of Laurens, Otsego County, New York, US 24,338, 7 June 1859. He meant it to be simple, cheap and portable, almost wholly of wood, with metal strips only to face the groove, and claimed the wheel, shaft, cam and lever together. He gave no sizes: the tilt, the platform, the cam's two zig-zags and throw, the lever and the bucket churn are ours.