66 DAIRYING 



others some tread power is used, and in still other places a gaso- 

 line or steam engine is the customary power. In addition to these, 

 electric motors and water power may be used. 



352. The tread power is not always satisfactory or econom- 

 ical unless some farm animal besides a horse is used. A dog or 

 sheep is not satisfactory in a tread power, but a bull is occasionally 

 used for this purpose with excellent results. 



The power must require little attention ; it must be uniform 

 and so attached to the separator that its speed will not vary. 

 Gasoline engines are used a great deal ; electric motors give a 

 uniform speed, and a steam engine has not only the advantage of 

 being a good power, but the necessary steam boiler gives a sup- 

 ply of steam and hot water that is always useful and needed for 

 heating the milk and for cleaning the tinware, separator bowl and 

 other utensils used in handling milk. 



353. If large quantities of milk are to be skimmed each day, 

 several small separators are better than one or two excessively 

 large ones, as one may be started earlier than the others and 

 later on stopped and cleaned while the others are running. 



354. The cost of the power is not always in proportion to 

 the amount of milk skimmed, as the equipment must be large 

 enough to take care of the maximum amount of milk that will be 

 received and all the machinery must be run except some of the 

 separators for smaller quantities of milk. Hand power at farms 

 may be expensive for running separators because of the uneven- 

 ness of the speed kept up. This, however, may be regulated by 

 using a watch to time the crank revolutions if necessary. 



355. If small quantities of milk are to be skimmed at a farm 

 by steam engine power, the milk must either be cooled at one 

 milking and then heated to a skimming temperature at the next 

 milking, or steam raised in the boiler after each milking. The 

 difference in labor or expense of the two practices must be de- 

 cided at each farm. 



