38 The Colorado Experiment Station. 
The inside form is raised above the level of the finished wall and 
allowed to hang from locked pulleys. Cut 5 shows how a level rest 
is then made that the forms may be lowered upon. 
A mark is drawn around the center 2x4 just two inches below 
a point level with the top of the finished wall. Arms are then run, 
on the level of this mark to the wall of the silo, one such arm being 
nailed to each of the eight or ten (as the case may be) of the out¬ 
side legs of the scaffolding. These arms should each meet the con¬ 
crete wall. In cut 5 you are looking down upon the scaffolding 
after these arms have been placed, the working platform laid and the 
inside form lowered to position. When the inside form is lowered 
upon these arms it should be perfectly level and should lap two 
inches below the finished wall. The form should then be spread to 
its normal diameter by manipulating the adjusting bolts. It will 
thus be forced out tightly against the wall at all points. 
The form should be made plumb each time it is set, but in case 
difficulty is encountered in spreading it to its proper diameter, in 
other words, if the circle of the silo seems to be growing smaller, 
the top of the form may be flared outward slightly to overcome this 
tendency. 
Reinforcing .—After the inside form is set, the reinforcing is 
then put in place. Use hog wire with 6-inch stays. Cut 7 shows 
the inside form raised and set and ready for reinforcing. In the 
courses below the door, the reinforcing will reach entirely around 
the inside form and will be tied at the point of meeting. About 
nine inches should be allowed for tying in this case. After the door 
is started the reinforcing will be tied to the pipes, on either side of 
the door. The allowance for tying will be doubled in this case for 
the two ties. The reinforcing after the door is started will, there¬ 
fore, be cut long enough to go around a circle of one foot greater 
diameter than the silo, plus 18 inches for tying, minus the 26 inches 
between the door posts. The distance around the circle may be 
determined by multiplying the diameter by 3.1416. Each strand 
of the wire should be tied to the door pipe. This cannot be done 
after both forms are raised and care must be taken to have the re¬ 
inforcing the proper length when tied. 
Position of Reinforcing .—The reinforcing is set at the outside 
l ather than in the center of the concrete wall. It is held in place by 
boards (spacers), 5 or 6 inches wide (according to the thickness 
of the wall), set edgewise at intervals of about 2^2 feet between 
the inside form and the wire. These same spacers also hold the out¬ 
side form in position. The reinforcing and the outside form are 
held in contact by the spacers. If instructions are followed in tamp¬ 
ing the concrete, the reinforcing will not show when the outside 
