770 MAIZE 



chap. 750. Floor. — If the silo is built on a soil that is dry all the 



XVI ' year round no other floor is necessary. Broken stones might 

 be laid over the floor to a depth of 6 to 8 inches, and then 

 covered with a layer of clean, dry earth or ant-heap, and rolled 

 or rammed till a compact and even surface is formed. Such a 

 floor could only be used where the ground is sufficiently dry 

 and where there is no danger of destructive insects or vermin 

 entering through the floor. In other cases a floor of cement 

 concrete should be laid, 4 to 6 inches thick, on a bed of broken 

 stones, as above described, and tile-pipe drains might also be 

 put in to carry off the water to some lower level. 



751. Walls. — The thickness of the walls depends greatly 

 on the material used in the construction, and on the size of the 

 silo. The larger and deeper the silo the greater is the pressure 

 on the walls, and with an increase of pressure there must be a 

 corresponding increase in the thickness of the walls. For a silo 

 of the capacity referred to in the preceding pages, built with 

 stone, the walls should be at least 22 inches thick at the base, 

 but may be diminished to 16 inches at the top, where the 

 pressure is considerably less. If built with brick, the thickness 

 might be 22 inches, or 2-J bricks, at the bottom, diminishing 

 to 14 inches, or I \ bricks, at the top. Stout hoop-iron bands 

 or iron rods are frequently built into the walls to strengthen 

 them, particularly near the doors, where the proximity of so 

 many openings tends to weaken the masonry. If built of rein- 

 forced concrete a thickness of 6 inches for the full height is 

 sufficient. 



752. Plaster. — To facilitate the settling of the silage the 

 walls of brick or stone silos should be plastered inside to a 

 perfectly smooth surface, with a thick coating of cement plaster, 

 which must be of the very best quality and well put on, as the 

 acids in the silage are apt to soften it and cause it to crumble 

 away. Concrete silos require only to have all rough parts 

 scraped off, and the surface, both outside and inside, rubbed 

 over where necessary with a canvas pad and neat cement to 

 fill up any air bubbles or other small holes. Where an inferior 

 class of bricks is used in the construction of the walls the out- 

 side face should be plastered with cement plaster, but if the 

 bricks are of good quality they may be left exposed and the 

 joints filled up and struck as the building proceeds, or after- 



