BUILDING THE SILO. 321 



using the stone silo where the climatic conditions 

 are suitable. 



The Doors. Provision ought to be made for 

 the door spaces when the wall is being built. These 

 should be on one side of the silo and above one 

 another, as in the stave silo. The size of the door 

 spaces should be about the same, that is to say, about 

 18x24 inches, or perhaps a little larger than that, 

 because of the greater thickness of the stone wall. 

 The material for the doors within and without will 

 of course be wood, with tarred paper on the surface 

 next the air space and also on the beveled edges. 

 These beveled edges will fit into a corresponding 

 bevel on the four edges of the inner and also on the 

 outer surface of the wall, which border on the open 

 space left for the doors. But the bevel on the outer 

 side is much less important than that on the inner 

 side, and may be dispensed with altogether. The 

 doors on both sides may swing on hinges of suitable 

 construction, or they may be simply put in place 

 while the silo is being filled. 



In deep and wide stone silos it may be necessary 

 to strengthen the walls, to some extent, with iron 

 bands encircling them, or with iron rods running up 

 and down, as, for instance, near the doors. 



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