_Dairy Appliances_ have come in for a large share of attention at the hands of the Nineteenth Century inventor. There are about sixteen million milch cows in the United States, and their contribution to the food stuffs of the day in milk, butter, and cheese is no insignificant factor. There have been over 2,700 patents granted for churns alone, and besides these there are milk coolers, cheese presses, milk skimmers, and even cow milkers. The centrifugal milk skimmer is an interesting type of this class of machine. In the old way the milk was set for the cream to rise, which it did slowly from its lighter specific gravity. In the centrifugal skimmer the milk is continuously poured in through a funnel, and the cream runs out continuously through one spout, and the skimmed milk at the other. An illustrative type of this machine is shown in Fig. 169. A steam turbine wheel near the base turns a vertical shaft bearing at its upper end a pan which rotates within the outer case. The milk enters through the faucet at the top, and as the pan within rotates, the heavier milk, by its greater specific gravity, is thrown to the outer part of the pan and passes out through the larger of the two spouts, while the lighter cream is crowded to the center and passes out of the upper spout, which opens into the center of the pan. Patents to Lefeldt & Lentsch, No. 195,515, Sept. 25, 1877, and Houston and Thomson, No. 239,659, April 5, 1881, represent pioneer milk skimmers of this type. [Illustration: FIG. 169.--CENTRIFUGAL MILK SKIMMER.] Closely allied to the dairy appliances are the incubator and the bee hive, both of which have claimed a large share of attention, and for which many patents have been granted.