Concrete Silos . 29 



spent upon it each year to maintain it in reasonably 

 good condition is not as close to the ideal as we should 

 be able to get. For one thing this maintenance is an 

 annoyance and an expense, and for another thing it is 

 likely to be frequently neglected, thus reducing the 

 preserving power of the silo. 



(9) Shape. The cylindrical silo is most econom- 

 ical of material, easiest to provide with resistance to 

 working strains, easiest to fill. The absence of corners 

 makes it practically impossible for air pockets to form 

 if reasonable care is exercised in filling. 



(10) Smoothness of Interior Walls. By having the 

 interior walls smooth and free from ledges or offsets, 

 the silage will settle down perfectly, thus effectually 

 excluding the air and also allowing the largest pos- 

 sible amount of silage to be placed. 



