EXPERIMENT STATION BULLETINS. 



257 



In laying up the blocks the inner surface of the wall was kept per- 

 pendicular. When the wall was completed the inner surface received 

 a % inch coat of rich cement plaster, screened sand and cement in the 

 proportion of 3 to 1. 



Fig. 20 shows a form for making cement blocks. This is a modifica- 

 tion of the Stoll form. 



There are 4 doorways to the silo, each 23 inches wide and 4 tiers of 

 blocks high (3G inches). The lower door rests on the foundation and 

 all the doors are sep-iarated from each other by 4 tiers of blocks. There 

 are no door frames. The doors are very simply made of one thickness 

 6 inch common flooring, nailed to two cleats and just fill the opening. 

 They rest against no jambs. Nailed upon the inner surface of each 

 door and overlapping ends and sides by 4 inches is a piece of galvanized 





Fig. 20. Plans and elevation of form for making cement blocks. 



sheet iron. Each door is set in place from the inside and is held from 

 slipping outward by the sheet iron. The pressure of the ensilage 

 material against the sheet iron seals the doorway. The question 

 naturally arises concerning the strength of this sheet iron lining used 

 in this way. After two seasons' use there does not appear any evidence 

 of insufficient strength in this arrangement of door. 



The walls were reinforced by imbedding two strands of barbed wire 

 in the mortar underneath the first tier of blocks below each doorway 

 and in the mortar over the tier of blocks above each doorway. 



For the roof, eight 2x4 rafters were used and were given a 2 feet 

 rise to the center. The rafters were covered with sheeting, leaving a 

 scuttle door 2 feet x 3 feet and the sheeting was covered with a 3 inch 

 layer of cement mortar. The rafters were set upon plates bolted to 

 the top of the wall, the bolts being set in the cement. 



This silo has been filled twice. When the silage was removed it was 

 found that for the upper few feet the ensilage was more or less spoiled 

 33 



