14 HOW TO BUILD A SILO. 



If the silo has an inside diameter exceeding 15 feet 

 it will be necessary to use two or three hoops according 

 to diameter. When the diameter is greater than 25 feet 

 it will usually be best to use rafters and headers cut in 

 for circles 4 feet apart to nail the roof boards to, which 

 are cut as represented at H, Fig. 2. 



The conical roof may be covered with ordinary shingles, 

 splitting those wider than 8 inches. By laying the butts 

 of the shingles % to % of an inch apart it is not neces- 

 sary to taper any of the shingles except a few ft courses 

 near the peak of the roof. 



In laying the shingles to a true circle, and with the 

 right exposure to the weather, a good method is to use a 

 strip of wood as a radius which works on a center set 

 at the peak of the roof and provided with a nail or pencil 

 to make a mark on the shingle where the butts of the 

 next course are to come. The radius may be bored with 

 a series oi holes the right distance apart to slip over the 

 center pivot, or the nail may be drawn and reset as de- 

 sired. Some carpenters file a notch in the shingling 

 hatchet, and use this to bring the shingle to place. 



Ventilation of the Silo. 



Every silo which has a roof should be provided with 

 ample ventilation to keep the under side of the roof dry, 

 and in the case of wood silos, to prevent the walls and 

 lining from rotting. One of the most serious mistakes in 

 the early construction of wood silos was the making of the 

 walls with dead-air spaces, which, on account of damp- 

 ness from the silage, led to rapid "dry-rot" of the lining. 



In the wood silo and in the brick lined silo it is im- 

 portant to provide ample ventilation for the spaces be- 

 tween the studs, as well as for the roof and the inside 

 of the silo, and a good method of doing this is represented 

 in Fig. 3, where the lower portion represents the sill and 

 the upper the plate of the silo. Between each pair of 

 studs where needed a 1^-inch auger hole to admit air is 



