70 



SILOS: CONSTRUCTION AND SERVICE 



If strong 1-inch hardwood lumber is at hand, it may be 

 substituted for the 2-inch upper foot planks shown in the 

 drawing. In fact, this plan may often be changed to suit 

 the materials at hand, but in case all new materials are to be 

 bought, the plan shown will be found to give general satis- 



Fig. 20. A scaffold for the Iowa silo. 



faction since all parts, having been used repeatedly, are 

 known to be sufficiently strong. Four upright posts, M, 

 secured to the wall at points approximately equally spaced, 

 support the scaffold platform by means of %-inch round 



