SEPARATION OF CREAM. 



131 



In 1875 Prandtl exhibited at Frankfort-on-the-Main a con- 

 tinuous separator, which did not at the time attract much 

 attention, due chiefly to the excessive amount of power needed 

 to overcome the resistant force of the air. In 1876 a Danish 

 engineer named Winstrup succeeded in improving the old 

 bucket method. In 1877 Lefeldt and Lentch offered for sale 

 four continuous separators with different capacities (from 1 10 

 to 600 pounds of milk per hour). During that year also the 

 first practical centrifugal creamery was established at Kiel, 

 Germany. In 1877 Houston and Thompson of Philadelphia 

 filed a patent for the continuous method of separation of cream 



Fig. 70. — First centrifugal separator. (From Dairy Messenger.) 



from milk. The patent was allowed in 1891. In March, 1877, 

 Lefeldt and Lentch invented a separator similar in construction 

 to the hollow bowl — a more recent type. This machine did not 

 revolve at so rapid a rate as our modern machines do, nor 

 did it have arrangements for continuous inflow and discharge. 

 It was intermittent in its work, and it was necessary to stop 

 at intervals to remove the cream and skimmed milk. 1879 

 was the year which marked the greatest advancement toward 

 the perfection of modern separators. The appearance of the 

 Danish Weston, invented in Denmark, and the De Laval, in- 

 vented in Sweden during that year, marked a great advance- 



