Early hand crank "Official Babcock Tester" centrifuge for measuring the butterfat content of milk in the farm dairy or creamery. This is an early hand-cranked model with brass canisters. It is marked with raised letters on the cast iron housing "Official Babcock Tester". We didn't see a date, but are guessing turn-of-the-century as we've seen advertisements for this centrifuge made by Cornish, Curtis and Greene Manufacturing of Fort Atkinson, Wisconsin from 1904.
In 1890 Stephen Babcock (a professor at the University of Wisconsin) invented a test for measuring the amount of butter fat in milk, either on the farm or in the dairy or creamery. The test, which is still know to this day as the "Babcock Test", involved placing samples of the milk in a glass vial with a calibrated neck and then spinning them at high speed in a centrifuge. This causes the cream to separate from the non-fat milk and by reading the level on the vial, the tester can determine the percentage of cream in the milk.
This tester is made to either clamp or screw onto a table top or work bench. It measures about 9" high overall and about 9 1/4" across the wheel. The brass canisters are about 1 7/16" across and 3 1/2" deep. This is in nice vintage condition, the gears are free to turn and it cranks nicely, but is does have rust to the iron and tarnish to the brass canisters.