"As we are going to use more butter, I think it would be a good thing to start in on our cream separator," said George, who, while he was not an adept, like Harry, to devise the things required, was always ready to suggest things that could be made to advantage.
"I know that Harry will be very glad to set to work on that, so we might as well commence," answered the Professor.
"What is the principle of the separator that causes the cream to break away from the milk?"
"Centrifugal motion is employed to bring it about."
"But how does that motion affect it?"
"When you put a ball on an elastic and swing it about your head in a circle, the elastic stretches in proportion to the speed at which you swing it. You have probably seen it done. It is stretched in proportion to its weight, also. These two things, therefore, are properties of centrifugal motion. Cream is the fatty portion of the milk. It is contained in little globules, and when the milk is allowed to stand, the milk surrounding the globules, being heavier than the cream, forces its way to the bottom, and the cream by that means goes to the top. The inventor has taken advantage of this fact by making a machine which will take the milk and impart to it a very high centrifugal motion, and in doing so the milk particles, on account of their greater weight, force their way outwardly and the cream inwardly. The machine is also so arranged that the cream and milk are drawn from it at separate points, and this operation is a continuous one."
Harry quickly understood the machine from the drawing made for his guidance, and in Figure 28 a sketch is made, showing how it was constructed.
