668 THE COMPLETE GRAZIER. BOOK VIH. 



siderable popularity. It consists of a covering of boards from to 

 1 inch thick, laid on purlins of 7 inches by 2| inches, spaced from 

 4 feet to 5| feet apart. These rest on principal rafters placed from 

 14 to 16 feet apart, their scantling depending on the width of span for 

 which they are required. For a span 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 durable. 

 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, 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 quantity extremely small 

 quite too insignificant to interfere with the comfort of the animals or 

 to impair the quality of the manure. Indeed, it has been proved that 

 less rain penetrates than when close boarding is used a curious fact, 

 and not easily accounted for, but a fact nevertheless. 



The higher the pitch of the roof the sooner the rain flows off it, and 

 this tends to its preservation ; but it is not well to go beyond a given 

 pitch, as, when too high, the rain is found to enter in greater quantity. 

 Lord Wenlock's agent at Escrick, Mr. Walker, who has erected a great 

 many of these roofs, and particularly noted this point, finds a rise at 

 an angle of 40 degrees to be the happy medium between a high and a 

 low pitch. He also advocates a moderate rather than a wide span, 

 finding the water does not get so well away on long-sided roofs than 

 where they are shorter, and is more liable in strong winds to be blown 

 through the openings into the yards. 



The first to adopt this board-roof was Mr. Cundy, land-agent of 

 Wetherby, he having got the idea of its leading principle from a brick- 

 maker, who found that his bricks were kept drier when his shelter 

 boards did not absolutely touch than when in contact. This induced 

 him to cover, by way of experiment, a small yard embodying the 

 principle, and the result proved so satisfactory that he has gone on 

 covering ever since. 



That a wooden roof is a better equaliser of temperature than any of 

 the others mentioned will be readily admitted. That the Cundy roof 



