26 



There are tvro general tyi.es of fanning mills. In the first 

 the air is directed upon the grain as it passes over the sieves; 

 and in the second the air "blast is independent of the sieves and 

 riddles. 



The first of these is the older type. It has a rather larger 

 capacity for the amount of sieve surface provided and when proper- 

 ly handled will do good work. A diagram of a mill of this sort 

 is shown in figure 2. The latter type, however, has the great- 

 er refinement and is capable of more careful selections. Diagrams 

 of machines of this type are presented in Figs. 3 and 4. 



From a Minnesota Bulletin we get a diagram that is quite 

 helpful to the understanding of some of the arrangements of a 

 mill of this sort. See Fig. 5. (63) 



Figure G. (64) shows an arrangement where selection is be- 

 ing made on the "basis of density alone. This would also blow 

 out a great deal of the trash and dust. 



Other machines are designed to make selection merely on 

 the basis of size. Herewith are presented three cuts to illus- 

 trate one means of sorting for size which should be capable of 

 considerable refinement. In any mill of this kind the efficiency 

 of selection decreases with the increase in amount of grain 

 put through per hour. These are taken from Cobb's work (65) 

 and are presented to show first (Fig. 7) the simple principle 

 on which they work and are kept clean. Here note the brush 

 for keeping the meshes cleared of grains which are Just large 

 enough to wedge slightly without going through. It seems to the 

 writer that considerable efficiency must be lost by some of the 

 commercial machines in this manner. 



Fig. 8 shows a more elaborate mill which makes selection 

 of several sizes and blows out dust and chaff. 



