BUILDINGS, AND THE MANUFACTURE OF MANURE. 67 



any portion except the purlins need not exceed 4in. by IJin. 

 Open slating is used as cheaper, lighter, and allowing more 

 perfect ventilation, which is further secured by placing the 

 plates on pillars such a height above adjoining buildings 

 as will allow of an open space of from 7in. to 9in. A 

 roof of this kind will cost from 5s. to 7s. a yard of ground 

 covered. A still cheaper, but less durable, roof consists 

 of light principals 14ft. apart, carrying purlins 4in. by 3|in., 

 about 4ft. 6in. to 5ft. apart, supporting rough fin. boards, 

 which are laid from the ridge to the eaves, with one- sixth of an 

 inch spaces between. About Jin. from the edge of the board is 

 a groove fin. deep. The boards are nailed to the purlins, but 

 actual contact is prevented by the presence of three clout nails 

 under each board, and thus any moisture which collects on the 

 under side of the boards can run down the face of the board 

 without injuring the purlin. It is found that by leaving the 

 spaces between the boards, less rain penetrates than if in 

 contact. The globules of water run down the open space 

 without breaking. Only very fine mizzle or a small driving 

 snow penetrates, and that only to a limited and not injurious 

 extent. The cost of such a roof should not exceed about 3s. 

 a yard of ground covered. Though not so durable as the first 

 described, such roofs are well adapted for construction when 

 the surrounding buildings are old, or by a tenant on a lease or 

 who has a protective agreement from his landlord. 



5. Cost and Return. — Taking a farm with mixed stock, 120 

 square feet is an ample allowance of ground space for each 

 animal. Assuming a cost of 7s. Qd. a yard, we have a first cost 

 of 5Z. per head, and, charging for interest and repayment of 

 principal 6f per cent., we have an annual charge of 6s. 6d, per 

 animal per annum. If the saving is as we believe 2Z. 14s., 

 then it is clear that great economy results from the use of 

 properly-constructed buildings ; and this will be in proportion 

 to the humidity of the climate and the value of straw. It 

 should be remembered that covered yards effect a great economy 

 in ground space ; so much so that when new buildings are 

 made we believe the cost for a given number of animals will not 

 be greater than with open courts and sheds. . 



So much for the great advantage of covered yards. All, 



F 2 



