and Great Britain in the year 1879. The century closes with 35,000 to 40,000 of these machines in operation in the United States. The second great dairy invention of the period is the fat-test for milk,—being a quick and easy substitute for chemical analysis. This is one of the public benefactions of the Agricultural Experiment Stations which, under State and national endowment, have been established during the last part of the century, so that there is now at least one in every State. A number of these have done much creditable work in dairy investigation, and from them have come several clever methods for testing the fat content of milk. The method which has been generally approved and is now almost universally adopted in this and other lands is named for its originator, Dr. S. M. Babcock, the able chemist and dairy investigator, first of the New York Station at Geneva and since of the Wisconsin Station at Madison. This tester combines the principle of centrifugal force with simple chemical action. The machine, on the Babcock plan, has been made in a great variety of patterns, simple and inexpensive for home use, more elaborate and substantial for factories. By them from two to forty samples of milk may be tested at once in a few moments; and by slight modifications in the appliances, the fat may be determined in samples of milk, cream, skim-milk, or butter-milk. This fat test of milk has wide application, and is second only to the separator in advancing the economies of dairying. The percentage of fat being accepted as the measure of value for milk for nearly all purposes, the Babcock test may be the basis for city milk inspection, for fixing the price of milk delivered to city dealers, to cheese factories and creameries, and for commercial settlements between patrons in coöperative dairying of any kind. By this test, also, the dairyman may prove the quality of milk from his different cows, and (with quantity of milk-yield recorded) may fix their respective value as dairy animals. With perfect apparatus in careful hands, the accuracy of the test is unquestioned, and it is of the highest scientific value. It should be noted that although clearly patentable, and offering an independence through a very small royalty, this priceless invention and boon to dairying was freely given to the public by Dr. Babcock. [Illustration: CENTRIFUGAL CREAM SEPARATOR IN OPERATION.]