162 SWINE 



has been fired and everything is in readiness to begin 

 threshing, this may be compared to the process of swine 

 feeding. The wheat that is used in the engine for fuel 

 represents the feed used by the pig for maintenance and 

 to furnish the energy for digesting and assimilating the 

 feed, also to excrete the waste products. The grain that 

 goes into the sack represents the gains made; the grain 

 that blows over, the waste; and the straw, the feces. 

 When the machine is run empty, the wheat used as fuel 

 in the engine represents the actual quantity of feed used 

 for maintenance, after eliminating the factor of waste. 

 As grain is fed into the machine, more fuel is required in 

 the engine ; some to handle the material that is being fed 

 into the separator, besides that to run the machine itself. 

 When grain is fed into the separator only in small 

 quantities, the effectiveness of the machine is greatest ; 

 that is, under these conditions more of the grain is saved. 

 As the machine is being crowded toward the upper limit 

 of its capacity, more grain is left in the straw, and more 

 passes across the sieve, because a larger part of the sieve 

 becomes clogged, allowing a smaller quantity of grain to 

 pass through into the sack or wagon. More grain is also 

 required to furnish the necessary fuel in the engine. Now, 

 as the upper limit is reached so that the engine is pulling 

 a full load and the sieves have become largely clogged 

 so that a considerable portion of the grain goes into the 

 straw stack, and the amount of grain fed into the sep- 

 arator is again reduced, the machine gradually becomes 

 more effective ; that is, as a smaller amount of grain is fed 

 into the separator, less fuel is required in the engine, 

 more grain is threshed out of the straw, and more of the 

 material that has clogged the sieve is gradually rattled 

 out, allowing more of the grain to pass through into the 



