138 



FARMERS' RKGISTER. 



[No. 3 



2» / 



of the kiln be sunk, and the more capacious it 

 maybe made. When the site is determined upon, 

 the surface ground should be levelled, and the 

 upper dimensions of the kiln accurately traced. 

 The body is then excavated, the sides and ends 

 gradually sloping in the manner represented in the 

 dotted lines in this transverse section ol' the eleva- 

 tion of the breast of the kiln. 



When the excavation has been completed to a 

 depth sutficient for the furnace and flue, the trench 

 for the latter, thus made Irom the breast to the 

 back of the kiln, has a gradual declination from 

 the back part, or chimney, for the purpose of let- 

 ting of!' water ; the inside is lined with bricks 

 placed lengthwise. These two walls, four inches 

 and a half thick, form the pier or support of the 

 open arch, which is made with arch bricks, laid 

 broad, also lengthwise; so that each arch is nine 

 inches, leaving open intervals of four inches and a 

 half. The open arch should have three ties, or a 

 continuation of bricks, one along the key, or centre, 

 and the other two along the sides, at half the dis- 

 tance between the key and the spring of the arch. 



These ties render the whole of the open arch firm, 

 and not liable to be deranged by the heavy load of 

 clay which is to be laid upon it. 



A kiln of the dimensions here described is stated 

 by General Beatson to require about 3000- bricks 

 Ibv its construction: mud mortar is used; and the 

 expense of building the furnace, flues, &c., is only 

 calculated at about 10/. or 12/. The size may be 

 either increased or diminished, according to the 

 measurement in the scale. 



The clay is at first laid on carefully in large pieces, 

 leaving wide interstices for the admission of heat- 

 ed air all along the arch of the main flue, and iron 

 flues in the sides, vrhen the kiln is large enough to 

 require them. When the clay has covered these 

 to the height of two or three feet, it may then be 

 heaped upon the kiln, but the large.st pieces should 

 be always put in first, and the smaller reserved 

 for the upper covering, in order to allow a free 

 passage to the heat through the interstices of the 

 latter. The clay should be rather in a moist state, 

 because, if laid on when too dry, it is apt to be 

 hardened by the heat; but if damp, or moist, the 

 whole becomes, in a manner, steamed, and cal- 

 cines into a light, porous substance, which easily 

 pulverizes upon being exposed to the air. — 

 A cart-load, or sixteen bushels, of moist clay, 

 weighs about 1500 lbs., but when burnt, the 

 weight is reduced to 1200 lbs. The kind of fuel 

 must depend upon circumstances; but, in the mid- 

 land counties, generally consists of wood, which 

 may commonly be procured at about 4s. the cord 

 for large roots in a rough state, or at the same 

 price per 100 for faggots. Upon an accurate ex- 

 periment, made in a small kiln, twenty-one feet by 

 nine, having a furnace and an open arch flue, the 

 result was, that with 275 faggots and half a cord 



