THE '"WISCONSIN" SILO. 41 



the wind out and make the silo warm in winter, free from snow 

 and freezing 1 , and the silage in good shape for feeding. 



The roof of cylindrical silos may be made in several ways, but 

 the simplest type of construction and the one requiring- the least 

 amount of material is that represented in Fig. 8, which is the cone. 



If the silo is not larger than 15 feet inside diameter no rafters 

 need be used, and only a single circle like that in the center of 

 Fig. 8, this is made of 2-inch stuff cut in sections in the form 

 of a circle and two layers spiked together, breaking joints. 



The roof boards are put on by nailing them to the inner circle 

 and to the plate, as shown in the drawing, the boards having- been 

 sawed diagonally, making- the wide and narrow ends the same 

 relative widths as the circumference of the outer edge of the 

 roof and of the inner circle. Thus a 10-foot board 8 inches wide 

 would be sawed so as to make two 10-foot lengths, each being 6% 

 inches wide at one end and 1% inches wide at the other. 



If the silo has an inside diameter exceeding 15 feet it will be 

 necessary to use two or three hoops according to diameter. 



The conical roof may be covered with ordinary shingles, split- 

 ting those wider than 8 inches. By laying the butts of the shingles 

 Vs to % of an inch apart it is not necessary to taper any of the 

 shingles except a few courses near the peak of the roof. 



The prepared roofings, such as "Ruberoid' r or "Paroid" or pre-. 

 pared gravel roofing are preferred to shingles for a silo roof, since 

 they make a tighter roof which retains the heat in winter. 



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 of holes the right distance 

 apart to slip over the center pivot, or the nail may be drawn and 

 reset as desired. 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 1 . One 



