296 BUILDINGS, SANITATION, AND DISEASES 
walls are constructed and is not likely to prove at all injurious 
to the pigs. 
A very good wall can be made by setting two-by-four 
seantlings on end, and first boarding inside and out with rough 
lumber. This rough lumber should then be covered with tarred 
paper, and then the walls should be tightly boarded up with 
matched lunber. If preferred, the outside of the pen may be 
clapboarded. Smooth, matehed lumber is best for the inside 
of the pen. Patent building paper may be used outside. 
If it is thought desirable to have a loft over the pen, the 
ceiling can be made of poles, placed a few inches apart, and 
well covered with straw. The straw absorbs moisture and helps 
to keep the pen dry. Where this is done, the straw should be 
renewed at least every vear, otherwise it becomes a harbor for 
dust and disease germs, 
Ventilation. Thorough ventilation is a great help in pre- 
serving drvness, but it is a difficult thing to secure in a piggery 
without unduly lowering the temperature. It is an aid to 
ventilation to provide a large air space; in other words, to 
have a high ceiling. The tendency at present is to do away 
with the common loft over the piggerv, and to have the space 
above the pigs extend to the roof. This gives more air space 
and makes ventilation a simpler problem, but it necessitates 
lining the under side of the rafters with matched lumber in 
order to prevent the pen from becoming tov cold. 
Shaft Ventilators.—The admission of fresh air ean be 
provided for by constructing shafts in the walls at intervals 
of fifteen or twenty fect. These shafts should not he more 
than about four bv six inches in size, and should open outside 
near the ground, and inside at the eciling. Provision should 
he made for closing, or partial closing, of these intakes when 
eold air is admitted too rapidly. The outlets may consist of 
