THIRTY-SIXTH ANNUAL CONVENTION. 307 



Durability. 



"After due consideration to all other points of merit to be 

 found in silos, the most desirable silo is the one that is the most 

 durable and will give the longest term of service. The dura- 

 bility of a silo depends, first upon its strength, and second, the 

 durability of the material used in its construction. 



"To be durable, any material must resist the action of the 

 weather, the constant wetting and drying, freezing and thaw- 

 ing in the winter season, and any disintegrating action which 

 may be due to the silage itself. Some material will disintegrate 

 with age, and other materials suffer from rapid decay when sub- 

 ject to the warm, moist conditions which exist in the silo. 



Care and Repair. 



"It is desirable that a silo require the minimum expenditure 

 in the way of labor and material for its up-keep. A silo which 

 must be adjusted for shrinkage and expansion is of less value 

 than one which does not need such attention. Often this work 

 is neglected, and loss results. 



"Some silos must be frequently repainted in order to present 

 a pleasing appearance. This means added expense. All parts 

 should be equally durable and lasting. The replacement of parts 

 which are short-lived, the substitution of new pieces for those 

 which have become decayed or faulty for any other reason, adds 

 materially in many cases to the cost of maintaining the silo. 



Frost Resistance. 



"In Iowa the winters are so severe that it is difficult to con- 

 struct a frost-proof silo. The silo wall which will prevent freez- 

 ing to the greatest extent is the most desirable. 



Convenience. 



"A silo should be convenient for filling and so arranged that 

 the silage may be easily removed from day to day during the 

 feeding season. The doors should be so constructed that they 



