SOME COMMON MACHINES 



533 



still fresh. 4. The cream obtained can be " ripened " more 

 evenly (see Arts. 402 and 446), thus producing butter of better 

 quality and flavor. 5. In most states and cities whole milk 

 offered for sale as food must contain a certain percentage of 

 butter fat (Art. 401). Practically all of the butter fat is 

 contained in the separated cream. It is common practice in 

 many states for milk dealers to separate the cream from the 

 skim milk in the milk they handle. By then mixing the 

 cream and skim milk in certain definite proportions they can 

 produce milk containing an unvarying amount of butter fat. 1 

 6. It is common practice for farmers to separate the cream from 

 the skim milk, shipping the cream to the creamery where it is 

 made into butter and feeding the skim milk on the farm, thus 

 saving much cost for transportation. 



THE FARM POWER HOUSE 



625. Regulating the Speed of Machines. In a farm power 

 house, as well as in a factory, different machines must run at 



CNVHt 8'OHft 



FIG. 334. Regulation of the speed of machines in a farm power house. 



different speeds. The proper speed for a dynamo is not the 

 same as that for a cream separator or a pump. It is often de- 

 sirable, however, to have a single engine and L!NE SHAFT from 

 which power is distributed to all the machines. By using pulleys 

 of different diameters and suitable gearing upon the machines, it 



1 This practice is prohibited by law in some states. 



