136 MISCELLANEOUS FARM SUBJECTS 



Construction of Silos. The first silos were mere pits in the 

 ground, but these were abandoned principally because of the diffi- 

 culty of feeding from them. The square or rectangular silos were 

 found objectionable on account of the difficulty of filling the cor- 

 ners so as to exclude entirely the air. Silos are now universally 

 circular in form, and are built out of staves, cement, concrete or 

 brick. The round silo has two distinct advantages. First There 

 are no corners in which decay may develop. Second The pressure 

 is equally distributed from the center to each side, so that there is 

 no unequal strain upon the walls or sides of the silo of this form, 

 while the pressure from above on the silage below is uniformly dis- 

 tributed. These advantages have been found to be so distinct and 

 important that at this time but comparatively few silos are built, 

 excepting of the circular form. 



Foundation. On building a silo it is of the utmost importance 

 to have a good foundation. It should extend below the frost line 

 and should rest on hard ground. If the silo is built of brick, con- 

 crete, or stone, a more solid foundation is needed than if wood is 

 used. In such a case it may be better to consult an experienced 

 mason, as the condition of the ground where the silo is to be built 

 may make considerable difference in its construction. Some build- 

 ers simply dig a trench and build a wall in this up to a level with 

 the surface. A better plan, however, is to excavate the dirt from 

 2 to 5 feet below the feeding floor of the barn and build a good 

 wall, beginning at the bottom of this excavation. The capacity 

 added to the silo will amply repay for the extra cost involved. The 

 bottom of the excavation may be somewhat larger than the top, as 

 the base of the foundation wall should be at least 24 inches thick, 

 while it need not be more than 8 inches thick at the surface of the 

 ground. 



The practice of digging a trench and filling with concrete is 

 not recommended unless the soil is firm and of such a nature that 

 it can be finished up smoothly. A tar or building paper lining 

 may be used to line the trenches in porous soils. It is difficult to 

 plaster concrete which has come in contact with the soil. In ex- 

 tending a part of the silo below the surface, the soil should not be 

 used as a part of the form. The concrete to be durable and economi- 

 cal should contain only clean and durable stone, gravel and sand. 

 Brick foundations should only be of hard burned brick laid in 

 cement mortar and when so built are considered satisfactory. 



The foundation should have such an effective bearing surface 

 as to prevent any appreciable settling. By effective bearing sur- 

 face or area of footing is meant the area of that part of the wall and 

 floor which in case of excessive pressure helps to carry the load 

 placed on it. Fortunately, the weight of the silage is supported 

 almost entirely by the floor and not by the foundation. The weight 

 on the foundation is practically only that of the wall and roof. For 

 a concrete silo under 50 feet in height, the width of footing need 

 not be over twice or three times as wide as the thickness of the wall 

 for any kind of soil except soft clay or quicksand. 



