32 PRACTICAL SILO CONSTRUCTION 



and steel centering by adding or removing sections 

 to make up the desired circumference. 



Where it is desired to erect an 8 " or 10 " wall for 

 a portion of the height, finishing with a 6" wall, 

 two sections of the form are fitted with steel sheets 

 to make the desired circumference. Then, when the 

 thickness of wall is to be reduced, the clamp is 

 slipped along the length of these sheets, allowing 

 the surplus length of sheet to lap over onto the one 

 that joins to same, thus reducing the circumference 

 of circle to mold a wall of the required thickness. 

 This leaves a mark of mold or indentation upon two 

 sides of silo, where the sheets lap; but, as this is 

 slight it will not be a serious defect to the work. 



METHOD OF RAISING FORMS 



The method of raising the forms after each 

 course is placed is shown at Fig. 5, as well as a 

 cross-section of wall and the molding form or cen- 

 tering. The vertical post shown at a a is made of 

 two 2x8" strips, placed together with a space be- 

 tween them of 2", so as to permit the braces b b to 

 slide between same as the silo forms are raised. 

 The two vertical strips, c c, are guides that are 

 bolted to the horizontal braces b b, and by press- 

 ing against the vertical posts a a the silo form is 

 kept from tipping to one side; nor is it allowed to 

 be raised higher at one side than the other. This is 

 a most important feature, and these guides should 

 never be left off the form, otherwise you will have 



