THE POLK SYSTEM 35 



The operation of the machine is simple. The forms are set, the 

 reinforcing bars arranged, the concrete is mixed, hoisted, dumped 

 packed between the forms, and allowed to set. On the next morn- 

 ing the nuts connecting the separable sections of the forms are 

 loosened and the forms swing free from the wall. Then by means 

 of the jacks the whole mechanism is lifted until in a position for a 

 new ''fill" when the forms are again tightened. The raising of 

 the forms for a set of 3 feet, 10 inches does not require more than 

 ten minutes work. It takes three men only fourteen days 

 to build a 16 x40 silo, everything complete. This includes 

 excavating, erecting, taking down and cleaning machine. 



'Thy are not built of pieces and they 

 cannot go to pieces. " 



