362 AGRICULTURAL ENGINEERING 



to give the grinder attention while in operation, a large one is 

 a decided advantage. A grinder using six to twelve horse- 

 power will grind feed at such a rate that one man will have all 

 he can do to provide grain for the hopper and to shovel 

 away or bag the ground feed. 



Ensilage cutters, when provided with a pneumatic ele- 

 vator or blower, require considerable power, and it is an 

 advantage to have a machine which will take undivided 

 bundles of fodder. To operate such a machine, a 12-horse- 

 power engine, or larger, is required. 



There are small threshing machines on the market which 

 require little power for their operation, and are no doubt a 

 success where a small amount of grain is to be threshed. The 

 small-sized machines, equipped with the modern labor-saving 

 attachments, such as the self-feeder and the wind stacker, 

 require about 12 horsepower for their successful operation. 

 The other larger machines mentioned may be procured in 

 almost any size to accommodate the size of the engine pur- 

 chased. 



From this analysis it would seem that there are two classes 

 of work on the average-sized farm which require two sizes 

 of gasoline engines if the work is to be performed economic- 

 ally. A certain portion of the fuel used by an engine is 

 needed to overcome the friction within the engine itself, or 

 to operate it. After enough fuel is furnished to keep the 

 engine in motion, the additional fuel used is converted into 

 useful work. The percentage of the total fuel required to 

 operate the engine proper, when under full load, is not far 

 from 25 per cent for average conditions. Thus it is seen that 

 it will require much more fuel to operate a 12-horsepower 

 engine empty, or under no load, than to operate a lJ/-horse- 

 power engine under full load. 



