Concrete Silos 137 



ends of the slabs. In order to accomplish this result 

 the slabs are laid up with even lateral joints and stag- 

 gered vertical joints, just the opposite of the general 

 custom in stave construction. The concrete ribs, being 

 carried completely around the structure, also form sills 

 and lintels for the door frames where they cross the 

 door openings. 



Everlasting Silo Staves. W. W. Rohrer & Son of 

 Orrville, Ohio, have a system of silo stave manufacture 

 to make staves 24 inches long, 10 inches wide and 3 

 inches thick. One vertical edge of each stave is con- 

 cave and the other convex, making a perfect joint. 

 Half length staves are used in starting the silo, so that 

 joints are broken all the way up. The staves are held 

 together with %-inch iron rods with patent knuckles. 

 As each row of staves is placed in position the hoop is 

 placed around and drawn up tight, each band passing 

 around the middle of half the staves and the ends of 

 the intermediate ones. 



It is claimed that a special mixture is used in mak- 

 ing these staves, rendering them impervious to mois- 

 ture and also acid probf. 



Panel Silos. These can perhaps best be included 

 under the general heading of stave silos, although in 

 this case the units run horizontally instead of ver- 

 tically. This system is controlled by the Concrete 

 Panel Silo Company of Kansas City, Missouri. It con- 

 sists of poured concrete columns alternating with pre- 

 cast concrete slabs. The slabs are 10 inches high, 24 

 inches long, and 3 inches thick. 



In erecting the silo, the slabs are first laid up to a 

 convenient height, with reinforcing rods in the hori- 



