IKON 997 



and the flue. The fireplace varies from 3 to 4 feet long, by from 2 feet 8 inches to 

 3 feet 4 inches wide. The door-way, by which the coke is charged, is 8 inches square, 

 and is bevelled off towards the outside of the furnace. This opening consists entirely 

 of cast iron, and has a quantity of coal gathered round it. The bars of the tire-grate 

 are moveable, to admit of more readily clearing them from ashes. 



Fig. 1258 is a longitudinal section referring to the elevation.^. 1257, and fig. 1259 

 is a ground plan. When the furnace is a single one, a square hole is left in the side 

 of the fireplace opposite to the door, through which the rakes are introduced, in order' 

 to be heated. 



a is the fire-door; b, the grate; <?, the fire-bridge; dd, cast-iron hearth-plates, 

 resting upon cast-iron beams e e, which are bolted upon both sides to the cast-iron 

 binding plates of the furnace ; / is the hearth covered with cinders or sand ; g, is the 

 main working door, which may be opened and shut by means of a lever </, and chain 

 to move it up and down. \In this large door there is a hole 5 inches square, through 

 which the iron may be worked with the paddles or rakes ; it may also be closed air- 

 tight. There is a second working door A, near the flue, for introducing the cast iron, 

 so that it may soften slowly, till it be ready for drawing towards the bridge, i is the 

 chimney, from 30 to 50 feet high, which receives commonly the flues of two furnaces, 

 each provided with a damper plate or register. Fig. 

 1260, shows the main damper for the top of the 1260 

 common chimney, which may be opened or shut to 

 any degree by means of the lever and chain, k, Jig. 

 1258, is the tap or floss-hole for running off the 

 slag or cinder. 



The sole is sometimes made of bricks, sometimes 

 of cast iron. In the first case it is composed of 

 fire-bricks set on edge, forming a species of flat vault. 

 It rests immediately on a body of brickwork either 

 solid or arched below. When it is made of cast 

 iron, which is now beginning to be the general 

 practice, it may be made either of one piece or of several. It is commonly in a single 

 piece, which, however, causes the inconvenience of reconstructing the furnace entirely 

 when the sole is to be changed. In this case it is a little hollow, as is shown in the 

 preceding vertical section ; but if it consists of several pieces, it is usually made flat. 

 . The hearths of cast iron rest upon cast-iron pillars, to the number of four or five ; 

 which are supported on pedestals of cast iron placed on large blocks of stone. Such an 

 arrangement is shown in the figure, where also the square hole a, fig. 1257, for heating 

 the rake irons, may be observed. The length of the hearth is usually 6 feet ; and its 

 breadth varies from one part to another. Its greatest breadth, which is opposite the 

 door, is 4 feet. In the furnace, whose horizontal plan is given above, and which pro- 

 duces good results, the sole exhibits in this part a species of ear, which enters into 

 the mouth of the door. At its origin towards the fireplace, it is 2 feet 10 inches 

 wide ; from the fire it is separated, moreover, by a low wall of bricks (the fire-bridge) 

 10 inches thick, and from 3 inches to 5 high. At the other extremity its breadth is 

 2 feet. The curvature presented by the sides of the sole or hearth is not symmetrical ; 

 for sometimes it makes an advancement, as is observable in the plan. At the ex- 

 tremity of the sole furthest from the fire, there is a low rising in the bricks of 2 J 

 inches, called the altar, for preventing the metal from running out at the floss-hole 

 when it begins to fuse. Beyond this shelf the sole terminates in an inclined plane, 

 which leads to the floss, or outlet of the slag from the furnace. This floss is a little 

 below the level of the sole, and hollowed out of the basement of the chimney. The 

 slag is prevented from concreting here, by the flame being made to pass over it, in its 

 way to the sunk entry of the chimney ; and there is also a plate of cast iron near 

 this opening, on which a moderate fire is kept up to preserve the fluidity of the scoriae, 

 and to burn the gases that escape from the furnace, as also to quicken the draught, 

 and to keep the remote end of the furnace warm. On the top of this iron plate, and 

 at the bottom of the inclined plane, the cinder accumulates in a small cavity, whence 

 it afterwards flows away ; whenever it tends to congeal, the workman must clear it 

 out with his rake. 



The door is a cast-iron frame, filled up inside with fire-bricks ; through a small hole 

 in its bottom the workmen can observe the state of the furnace. This hole is at other 

 times shut with a stopper. The chimney has an area of from 14 to 16 inches. 



The hearth stands 3 feet above the ground. Its arched -roof, only one brick thick, 

 is raised 2 feet above the fire-bridge, and above the level of the sole, taken at the 

 middle of the furnace. At its extreme point near the chimney, its elevation is only 

 8 inches; and the same height is given to the opening of the chimney. The sole is 

 covered with a layer of finely-pounded cinders from previous workings mixed with 



