312 ILLINOIS STATE DAIRYMEN'S ASSOCIATION. 



sible expense may be the occasional washing of the inside of the 

 walls at intervals of not less than five years, with a cement wash 

 and the replacement of the doors after they have become rotten 

 from use. 



Frost Resistance. 



Owing to the fact that all Iowa silos do not now have roofs 

 and that no two men use the same methods in feeding silage, it 

 has been difficult for the authors to compare the frost resistance 

 of different types of silos. It is, however, a very conservative 

 statement to say that the average amount of frozen silage found 

 in the Iowa silos during personal inspection trips did not exceed 

 the amount found in wooden silos in the same neighborhood 

 and under the same conditions of exposure. 



The hollow wall of the Iowa silo in which the circulation of 

 air is quite thoroughly restricted, tends to make it frost re- 

 sistant. Dry fir lumber is about six times as efficient a non- 

 conductor of heat as vitrified clay. Since the Iowa silo wall is 

 twice as thick as the average silo stave, and because it is only 

 about one-fourth solid, it should be at least equally as efficient 

 as a two-inch wooden wall which is always moist, a condition 

 which lowers the efficiency of wood as a non-conductor. The 

 Iowa silo wall, however, is not nearly as frost proof as a double 

 wall concrete silo or cement block silo with less material join- 

 ing the two walls and with restricted air circulation. 



Convenience. 



The Iowa silo has been designed and constructed with either 

 individual or continuous doors. The continuous doorway has 

 cross-ties 42 inches apart which is an important advantage over 

 the usual construction which in some instances has hoops or ties 

 as close as 26 inches. When cross-ties are close, the continuous 

 door offers but little advantage if any over the individual door. 

 With these improved doors, the Iowa silo offers as many advan- 

 tages for convenience in removing silage as any construction now 

 known. 



