EXPERIMENT STATION BULLETINS. 



247 



high above the floor. The floor stands 4i/i> feet below the surface of 

 the ground and 6 inches above the bottom of the foundation. 



The lower 3 feet of the foundation is of cobble-stone and cement. The 

 upper 2 feet is of concrete. The foundation is IOI/2 inches wide at the 

 top and broadens inward and outward to about 17 inches at the base, 

 the floor having a diameter of only 11 feet. The silo Avail above ground 

 has a uniform thickness of 8 inches and is unique in its construction. 





I 



-A 



* 







^ 



V 



Fig. 10. Outer elevation, section, and inner elevation of inner form used in the construction 



of the Porter silo (Fig. 8.) 





Fig. 11. Outer elevation, section, and inner elevation cf outer form used in the construction 



of Porter silo (Fig. 8). 



^ 



k- 



-/6- 



r' 



" , \^ 



Fig. 12. Form used to make hollow in the 

 construction of the wall of the Porter silo 

 (Fig. 8). 



