BRICKWORK. 97 



semicircular arches spring. The spandrils of these are faced with nine-inch 

 work, and the centre space filled in with concrete or brick rubbish. 



Plumb with the centre of each pier, level with the crown of the arches, 

 and having a bearing, at one end upon the face of the spandril, and at the 

 other in the outer wall, are placed the cast-iron girders G G, from which the 

 flat segments spring that support the flags of the firing-floor. The rise of 

 these arches is about twelve inches, formed of well-burned cut stocks, and 

 carried from the outer wall of the house to within two feet of the face of the 

 retort-benches. These flat arches are likewise carried across the coal-stores 

 and supported in a similar manner, as represented in the cross section. The 

 backings are filled in with concrete. 



The ovens for the reception of the retorts are separated by a 14-inch wall 

 running the entire length of the beds. In the immediate vicinity of the fur- 

 nace it must be constructed with fire-bricks laid Flemish bond. 



The walls on each side of the furnaces must be of Stourbridge fire-bricks, 

 and nine inches thick, as high as the springing of the arch, which is 4j inches 

 thick, turned with moulded bricks of the same description. The space 

 between the furnace-walls is fourteen inches. All the solid parts may be filled 

 in with brick rubbish. 



In turning the arches of the ovens, great care must be taken that the joints 

 are close, and for that purpose the clay used for setting the bricks must be 

 rendered fine with continued working. The bricks must be the best New- 

 castle, moulded to fit the curve. The flues must be faced with nine-inch 

 work, the intermediate spaces between the ovens filled in with concrete or 

 brick rubbish. 



H H is the hydraulic main. 



P P is the position for the cast-iron columns which support the main. 



Q is the pipe which conveys the gas to the separators or condensing pipes SS. 



The roof is of wrought-iron, constructed in the form shown in the en- 

 graving : the principals are twenty-two in number, eleven on each side, sup- 

 ported in the centre of the house by a cast-iron pillar resting on the wall which 

 separates the retort-ovens. The dimensions of the iron-work are, the prin- 

 cipal rafters three inches by five-eighths of an inch ; tie and brace- rods 1^ 

 inch round iron. The ventilator on each division is also of wrought-iron, 

 with the exception of the wind-boards, which are of three-quarter yellow deal. 

 The covering of the roof is of Countess slate. 



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