io6 THE POPULAR SCIENCE MONTHLY. 



The Babcock milk-testing machine is now just as generally- 

 sold by dairy firms as is an improved churn or butter-worker. 



One of the most wonderful of agricultural inventions is the 

 centrifugal or milk separator. Briefly, this machine is designed 

 to separate the cream from the milk as soon as drawn from the 

 cow, thus dispensing with the old process of setting milk and 

 waiting for the cream to rise by gravity. At the International 

 Dairy Show at Hamburg, in 1877, an instrument was exhibited * 

 consisting of two wheels in a stand, one of which actuated the 

 other by means of a belt. In the upper wheel four glass tubes 

 containing milk were securely placed, and the lower wheel was 

 then revolved, giving the upper upward of one thousand revolu- 

 tions per minute. Whirling at this speed brought centrifugal 

 force to bear on the milk in the tubes, and the cream, being light- 

 est, collected at one end and the skim milk at the other, f 



In 1879 De Laval, a Swede, exhibited to the British public at 

 Kilburn a centrifugal separator entirely unlike the preceding one, 

 and this machine of De Laval, in principle and general plan, is 

 the form now commonly used over Europe and America. Milk, 

 warm from the cow, is conveyed into a hollow steel drum about 

 ten inches in diameter, which is made to revolve six thousand to 

 seven thousand times per minute within a slightly larger metal 

 chamber. The skim milk, being heavier, is thrown to the outside, 

 and passes off through a tube which rises from a point in the 

 skim milk where the least amount of fat exists to the upper edge 

 of the drum ; while the lighter cream rises near the center of the 

 drum and passes off through another hole, coming out of the 

 separator on the opposite side from the skim milk. One or two 

 thousand pounds of milk an hour may be creamed with this ma- 

 chine, when run by horse or steam power. Several other designs 

 of centrifugals have more recently been invented, some of greater 

 capacity than the De Laval, but at the present day the modern De 

 Laval's is unsurpassed. For small dairies De Laval invented a 

 hand separator, which is known as "the baby separator." With 

 the No. 2 size one person can separate the cream from three hun- 

 dred pounds of milk in an hour, the drum making six thousand 

 revolutions per minute to forty -two turns of the crank. 



The manufacture of this cream separator has been followed 

 by the invention and introduction within the past two years of a 

 combined cream separator and butter extractor, which makes it 



* Sheldon, Dairy Farming, p. 303. 



f An editorial in Farm and Fireside, for June 1, 1892, states that the cream separator 

 has been in process of evolution for thirty-three years, and that the first known application 

 of centrifugal force for creaming milk was made in 1859. Dairy authorities, so far as I can 

 learn, give no data on the subject preceding that quoted above in the text. — C. S. P. 



