236 



STATE BOARD OF AGRICULTURE. 



To prevent the door frame from spreading, bolts of % inch iron are 

 placed at intervals of 30 inches from bottom to top. These bolts pass 

 through the center of the door frame and far enough beyond the second 

 stud to receive a 2 inch bj- 4 inch No. 10 steel washer and a large nut. 



Fig. 25. All wood silo, built in 1900. 



The inner wall consists of two' layers of I/2 iiich by 4 inch basswood 

 sheeting with a layer of tar paper between. In the construction, the first 

 layer was laid and well tarred with coal tar on the inner surface. 

 Over this was tacked the layer of tar paper which was then well coated 

 with tar. The second layer of sheeting was so laid over this paper as 

 to break joints with the first layer, and was later treated to a heavy 

 coat of coal tar. Both lasers of sheeting fall one inch short of outer 

 edge of the studs bearing the door frame. 



The outer wall consists of 3 % inch beveled basswood siding.^ The 

 lower inner edge carries a V2 inch rabbet, which makes it possible to 

 use beveled siding on cylindrical walls. 



