172 CULTURE OF FARM CROPS. 



each floor and that above it. The only labour to be per- 

 formed in connection with the above operation is to raise, 

 by means of an endless cup chain or otherwise, the grain 

 abstracted to the uppermost stage of the granary, the quan- 

 tity of which may be one-sixth, one-fifth, or one-fourth, as 

 the granary is composed of 4, 5, or 6 floors. 



" In the operations above described, the grains, in their 

 descent, occupying successively all the different stages be- 

 tween the summit and the base of the granary, are, there- 

 fore, by means of the friction, without pressure of the 

 grains against each other, cleansed from all foreign matters, 

 dust, and impurities which otherwise adhere to their sur- 

 face, but in this case escape by the perforated openings in 

 the upper part of each stage. The general movement thus 

 given to the whole mass of grain is also a great protection 

 against the insects. As a completion of this system one or 

 more wire lattices may be placed above the uppermost stage 

 of the granary, forming sieves on which the grain may 

 be, in the first place thrown, and which would retain all 

 such extraneous matters, as pieces of straw, &c., which 

 might be intermixed. For aerating the grain when at rest, 

 if required, by causing it to be traversed by currents of 

 air, some planks of about 8 inches in width may be placed 

 across the granary, and the walls under their extremities 

 may be pierced, thus giving admission to the air; the grain 

 in meeting with these planks falls on each side, leaving an 

 empty space beneath, of which the section would be that of 

 a triangle, the horizontal side being formed by the plank 

 and the others by those of the heaps formed by the grain. 

 For augmenting the ventilation a tube may be made the 

 whole height of the granary, to be fed by means of a 

 powerful ventilator at the base, and connected at each stage 

 with a smaller tube pierced with small holes and placed on 

 the floor. This system of construction may be employed 

 for a stove for drying grain by means of hot air. In this 

 case the apparatus should be constructed in iron, the floors 

 should be closer one to the other, and supposing a section 

 to measure 9 ft. by 9 ft., the distance between the floors 



