THE POLK SYSTEM 37 



of the wall. Owing to the shape and draft of this form the jamb 

 is left in perfect condition for sealing- the door when the form is 

 removed. Immediately after the machine has passed the opening 

 the form is removed, leaving the opening in perfect shape. 



The door itself is made of heavily galvanized No. 12 gage sheet 

 steel cut to fit snugly in the concrete jamb made by the form, flush 

 with the inner wall and bent to the radius of the silo. On the out- 

 side of the door are fastened four malleable clips in which hook 

 bolts engage and make a flexible fastening. Across the opening 

 on the outside of the silo wooden bars are placed, through which 

 these bolts pass. The desired stress is obtained by malleable tail 

 nuts. This combination gives you a LIGHT, DURABLE DOOR that is 

 air-tight. 



In sealing the door, a thin gasket of moist clay is smeared around 

 the inner surface of the jamb; the door is then set in place and 

 drawn tight by turning the tail nuts by hand. When the silage is 

 fed down past the doors, they are replaced in the openings and it 

 is necessary when refilling the silo only to smear the mud gasket 

 back of the door and draw it tight. It is then always in the place 

 in which it is going to be used. 



Can you conceive of a simplier operation that will solve the silo 

 door problem? The door is closed quickly, easily, lightly and se- 

 carely year in and year out without any trouble and expenses 

 other than that bit of clay. It fits as well and tight on the 10th 

 or 20th year as it does on the first. It is the IDEAL DOOR for the 



IDEAL SILO. 



"They are not buitt of piece* and they 



