THE EARTH'S BOUNTY 



tive widths as the circumferences of the outer 

 edge of the roof and of the inner circle. 

 If the silo has an inside diameter exceeding 



FIG. 3. CONICAL ROOF. 



15 feet, it will be necessary to use two or three 

 hoops, according to diameter. When the 

 diameter is greater than 25 feet, it will usu- 



90 



