26 



depending on the temperature. It must be remembered with both 

 the shallow and deep setting system that the best result is obtained 

 by "setting" the milk as quickly as possible after milking. Delay, 

 hauling or shaking in any way will prevent creaming. Nor will 

 cold air do the same work as water of the same temperature ; and 

 stone crocks or glass jars will not conduct the cold (or heat) as 

 quickly as tinned steel or copper. 



THE DEVONSHIRE SYSTEM. 



As another distinct system, must be mentioned that of Devon- 

 shire, where the milk is set in pans from 4 to 6 inches deep for 12 

 hours. The pans are then placed on the stove (or better still, pro- 

 vided with a double bottom for hot water) and the temperature 

 raised to 190 deg., or not quite boiling, after which the pans are- 

 set in the air for another 12 hours. The result is a thick, heavy 

 cream that may be removed in blocks the so-called Devonshire 

 cream. 



PRINCIPAL OF CREAMING BY CENTRIFUGAL FORCE. 



Mr. J. D. Frederiksen, in "The Dairy Messenger," explained 

 the principles of the process in such a clear, condensed manner 

 that I quote : "Tie a stone to the end of a string, take hold of the 

 other end of the string and swing it around at a rapid rate. As 

 the speed increases, the force with which the stone will pull the 

 string increases at a much greater rate than the speed, and the 

 weight of the stone seems to increase a hundred fold. This is due 

 to the centrifugal force, so-called, the tendency of the stone to fly 

 away from the center of revolution. 



"When a particle of matter is swinging round a central point,, 

 the force by which it presses outward from the center of revolu- 

 tion depends upon the gravity, the speed and the distance from the 

 center. Supposing a weight of one pound, w, to revolve around 

 an axis, the distance from the center (the radius) being r feet, 

 and the number of revolutions ^ hundred a minute, then the cen- 

 trifugal force /=3.4xRxWxS<?. Consequently, if r is one foot, the 

 centrifugal force will be: 



For 100 revolutions a minute 3. 4x 1 3.4 pout ds 

 " 200 " " 3.4x 4 13.fi 



4CO " " 34x '6 54.4 



" 1000 " " 3.4x 100 340 



" 5000 " 34x25008500 



"In other words, for 1,000 revolutions a minute, the dis- 

 tance from the center (r) being i foot, the centrifugal force 



