PLANT AND OPERATIONS OF SMELTER C. 677 



inlet pipes into the water- feeder R of each jacket. The heated water passes out 

 through the outlet pipes S into the gutter T (wrongly indicated as T 1 in Figs. 3 and 5). 

 The tuyere-holes n are placed at the junction of the water-jackets. 



The shaft of the furnace from the water-jackets up to near the top of the feed-holes 

 is lined with fire-brick. The rest of the masonry walls C" are made of common brick and 

 rest on a cast-iron carrier plate, 0, which in turn rests freely upon iron girders <?', three 

 on each side of the fuinace, which are firmly screwed and bolted to the capitals of the 

 hollow cast-iron supporting pillars P. The plate is in no way fastened to the girders, 

 so that its expansion and contraction are absolutely free. The obvious advantage of 

 this arrangement is to render the masonry absolutely independent of the pillars, so 

 that both keep their relative position unaltered by any lateral motion of the main 

 support. When the main cast-iron support is fixed to the pillars, as is the case in most 

 furnaces, the pillars are not nnfrequently cracked by the irresistible dilation of the 

 main support. Upon the cast-iron plate 0, an outer wall, N', extending up to the charg- 

 iug-floor, is built of common bricks. It is strongly braced by five rows of rails, Q, 

 inclosing flat vertical irons e and corner irons c. It is said that by the use of the outer 

 wall, which naturally protects the hotter parts of the furnace against external radia- 

 tion, a saving of 15 per cent, of fuel is effected; so that it must be considered as an 

 important part of the furnace. Each side wall of the furnace is provided with two 

 feed-holes, H ; but, while in most furnaces these holes arc placed in the middle of the 

 wall and are directly opposite each other, here they are placed to the left of the middle 

 on either side and thus are not directly opposite. This arrangement is necessitated 

 by the large dimensions of the furnaces and enables the feeders to distribute properly 

 the charge without effort. The feed-holes are provided, as usual, with sliding sheet- 

 iron doors, S 1 , and have cast-iron door-frames. The chimney D is braced at Q, and pro- 

 vided with corner irons c. It is connected with the dust-chambers by means of the 

 large sheet-iron flue F', which fits into a circular brick ring in the furnace wall, where 

 it is held in place by angle-iron rings. The damper G has riveted to it on its lower 

 face an angle iron rim, which rests in grooves filled with sand in the top of the furnace 

 wall, thus providing against any escape of fumes when it is closed. 



The arrangement for ventilating or carrying off the smoke of the tap-holes and 

 slags differs in these works from that ordinarily adopted. Instead of the hood Wand 

 chimney W in front of each furnace (as has been by mistake indicated in the eleva- 

 tion, Fig. 2, Plate XXXI), the whole front part of the building in which the furnaces 

 stand is made one big chimney by a partition wall, extending the length of the building, 

 running up from the charging-floor on the line of the front of the furnace, and slanting a 

 little backwards, so as to reach the middle of the ventilator at the ridge of the roof and 

 where the top of the furnace projects above it. Excellent ventilation is accomplished 

 by this simple method. 



Barring-down The barring-down of these furnaces is effected in the following 

 manner: To the upper end of the long, chisel-pointed bar (Fig. 7, Plate XLIV) is fast- 

 ened a long and strong rope; the bar is then introduced through one of the feed-holes 

 into the furnace, and the chisel point is forced by blows of a sledge-hammer between 

 wall and accretions. The rope is then thrown across the furnace to the other feed- 

 hole, and five or six men pull at the rope; voluminous masses of accretions are often 

 detached in this manner and are left in the furnace, where they arc subsequently 



