Covered Cattle Yards. 
479 
depending on the width of span for which they are required. 
For ours of 30 feet, 9 inches by 3 inches is amply strong enough. 
For cover, well-seasoned white-wood boards — owing to greater 
freedom from knots — are considered best, and are more frequently 
used than red-wood, although it is probable that the latter for this, 
or any similar outside purpose, would be more endurable. 1 They 
are used in widths of 7 and 9 inches— the former preferable as 
being less liable to warp. Before the boards are laid studs are 
driven into the purlins at the points where the boards would 
have come into contact with them, and the boards resting on 
these studs are then securely nailed to the purlins. The object 
of the studs is to allow a free downward course to any wet that 
may permeate the roof, and prevent its lodgment on the purlins, 
Fig, 4, — Section showing a Roof covered ivith Boards. 
besides securing a free circulation of air between the purlins 
and boards, and tending to the preservation of both from 
decay. 
The boards are laid \ inch apart, giving light to the yard, 
and also affording the means of ventilation. Grooves about \ inch 
wide, and \ inch from the edge, are made in them, with the object 
of catching the rain when blown athwart the face of the roof, before 
it reaches the openings, and conducting it down to the eaves 
spout. 
A special feature of this roof is that, though the interstices 
give sufficient light to the yard, and air enough for good 
ventilation, yet the wet that finds a way through them is in 
1 Mr. Dent prefers redwood, and has used it in such of his yards as are 
covered with boards. 
