THE HYDRAULIC or water-dilution sys like the gravity systems, depends upon the fact that the cream is lighter than the rest of the milk, but the force supplied for separating the cream oper ates in a horizontal direction rather than in a vertical direction, as is the case with gravity. Separation by the centri fugal method is accomplished through the use of some form of separator. The chief advantage of the centrifugal meth od is that the cream may be successfully separated under a considerable range of temperatures. Perhaps the best tempera ture is that of the normal body heat of the animal, the milk being run through the separator immediately after milk ing. A superior quality of cream can be obtained by the use of a separator, since the milk is not allowed to sour and the cream is therefore not subjected to the influence of bacteria which may have gained entrance to the milk. More over, the thickness of the cream, when the separator is used, may be regulated at will, whereas by the gravity system the amount of fat is never higher than 20 per cent. The fat is more completely removed by the use of a separator than by any gravity system and the skim milk is obtained sweet and in the best possible condition for feeding to calves and other animals.