48 SILOS: CONSTRUCTION AND SERVICE 



unless the foundation lies in dry, well drained soil, a drain tile 

 should be used to remove the ground water. The tile may 

 be located around the lower edge of the wall. If gravel or 

 cinders are used, they should be well tamped before the 

 foundation is put in place. 



In the case of the wood hoop silo, the walls may be set 

 flush with the inner part of the foundation of the silo pit, 

 using a heavy coat of asphalt or tar on top of the foundation. 

 The wood will then be protected from moisture of the foun- 

 dation, also the joint between the wall and the foundation 

 will be made perfectly air tight. In this case the pit is advis- 

 able. 



In case gravel is expensive or scarce it may sometimes be 

 economical to use brick or clay blocks for the foundation. 

 If they are used exclusively for the foundation of a clay 

 block silo, two 8-inch blocks may be laid side by side, making 

 the first course 16 inches wide. The next may be laid 

 crossways, making a 12-inch course. The third may then be 

 laid on edge, starting the 4-inch wall. 



Details of Doors. In stave silos found on the market, 

 very convenient doors are usually provided, so that little need 

 be said concerning their construction. There will be found 

 some difference in them, in that some are more nearly air 

 tight, stionger, and less liable to stick than others. 



For masonry silos, a cheap and very good door is shown 

 in Fig. 28. This door as shown is made of two thicknesses of 

 ship-lap that lap onto each other about two inches, and are 

 not beveled at the ends. The boards on the outer side are 

 shorter than those on the inside. A wide cleat with beveled 

 edges is nailed to the inner side of the door, on which the 

 different doors meet end to end, thus offering little obstruction 

 to the free settling of the silage. 



