TILTING OF STE£L. 



called the vault, built of fire-brick or Hone, which will with- 

 Ibiid ihc action of a moft intenfe heat, without cracking or 

 vitrification. D D in the fedion is the dome of the vau t, 

 and E E its upright fides, the fpace between which, and the 

 wall of the external building, is filled up with rubbilh and 

 fand. The vault, as is (hewn in the plan, is always four-hded, 

 that it may contain the pots which receive the iron bars to be 

 converted. A H reprcfent the two pots, built of fire-ftone, 

 each ten feet long, three feet deep, and two feet nine inches 

 wide ; the fpace between them is twelve inches wide ; and 

 dircd^Iy beneath it is the fire-grate. The pots are fupported 

 by a number of detached courfes of fire-brick, as (liewn at 

 , f (fig. 1. ) which leave fpaces between them, called flues, to 

 conduft the flame under the pots : in the fame manner, the 

 fides of the pots are fupported from the vertical walls of the 

 vault, and from each other, by a few detached ftones, 

 (/, /v. 1.) placed I'o that they may intercept as little as 

 poflible of the heat from the contents'of the pots. The adja- 

 cent fides of the pots arc fupported from one another by fmall 

 piers of ftone-work, which arc alfo perforated, as fhewn at 

 ,/ ( ifj. 2. ) to give pafl"age to the flame. The bottoms of the 

 pots are built of a double courfc of brick-work, about fix 

 inches thick ; the fides neareft together are built of a fingle 

 courfe of ftone, about five inches in thicknefs ; and the other 

 parts of the pots are fingle courfes about three inches, the 

 fides not requiring fo i-uch ftrength, becaufe they have lefs 

 heat and pren"ure to relill. 



The vault has ten flues or (hort chimneys, F F, rifing from 

 it ; two on each fide, to carry off the fmoke into the great 

 cone, (hewn in the plan 3, communicating with each fide, 

 and two at each end. 



In the front of the furnace, at H, an aperture is made 

 through the external building, and another correfponding in 

 the wall of the vault : thefe openings form the door, at 

 wliich a man enters the vault to put in or take out the iron : 

 but when the furnace is lighted, thefe doors are clofed by 

 fire-bricks luted with fire-clay. Each pot has alfo fmall open- 

 ings in its end, through which the ends of two or three of 

 tlie bars are left projefting in fuch a manner, that by only 

 removing one loofe brick from the external building, the 

 bars can be drawn out without difturbing the procefs, to 

 examine the progrefs of the converfion from time to time : 

 thefe are called the ta))-holes ; they (hould be placed in the 

 centre of the pots, that a fair and equable judgment may 

 be formed from their refult of the reft of its contents. 



a b, in the elevation, is the fire-grate, formed of bars laid 

 over the afti-pit I, which muft have a free communication 

 with the open air, that it may convey a current of frefh air 

 to fupply the combuftion. Tiie afli-pit (hould alfo have fteps 

 down to it, that the attendant to the furnace may get down 

 to examine by the light, whether the fire upon the whole 

 length of the grate is equally fierce ; and if any part appear 

 dull, he ufes a long iron hook to thruft up between the bars 

 and open a paffage for the air. The fire-place is open at both 

 ends, and has no doors. The fire-grate is laid nearly on a level 

 with the floor of the warjhoufe, before the furnace, and the 

 fireman always keeps a heap of coals piled up before the 

 apertures at its ends, fo as to clofe the opening. This forms 

 a very fimple and effeftive door; and when the furnace re- 

 quires a fre(h fupply of fuel, a portion of the heap of coals 

 is fhoved in by a fort of hoe, and the heap renewed, to ftop 

 any air from entering into the fjrnace, except that which has 

 paffed upwards through the ignited fuel, and by that means 

 contributed to the combuftion. ' 



The fire-ftones that eompofe all thofe parts of the fur- 

 nace which are expofed to the a£lion of the heat, are firft. 

 hewn nearly to fize, and finiftied by grinding two furfaces 

 together, fo that they make very perfeft and clofe joints : 



when laid together, they are cemented with wcU-tempere 

 fire-clay, mixed up very thin with water. The fire-clay which' 

 anfvvcrs beft for this purpofe, is that brought from Stour- 

 bridge, in Staifordfliirc, and is the fame of which the cele- 

 brated Stourbridge crucibles arc compofed ; but very good 

 fire-clay for the purpofe is procured from Birkiii-lane, near 

 Chefterfield. When the furnace has been once burnt, this 

 clay becomes equally hard with the (tone, and is lefs liable to 

 fly or vitrify in an intenfe heat, than any other known cement. 



The procefs of charging the furnace with iron for con- 

 verfion is condufted as follows. The bars of iron are firft 

 cut to the length of the pot'; and for this purpofe an anvil is 

 placed at fuch a diftance from the wall of the building, that 

 the diftance from tlie edge of a cold chilTel wedged into the 

 eye of the anvil, to the wall, will be juft the length of the 

 pots. One workman places the end of a bar againft the wall, 

 and lays the other end acrofs the edge of the chiffel, vvhilft 

 another with a (ledge-hammer ftrikes upon the bar till it is 

 cut half through; then it is turned the other fide upwards, 

 and the end cut completely off. By this gauge the bars are 

 all cut to one length, and a man enters through the door in 

 the vault, to difpofe of them in the pots : he is provided with 

 a baflict of fine pulverized charcoal, a lleve, and a fhovcl. An 

 iron plate is put into the furnace, and lays over the fpace 

 between the two pots to form the floor, upon which the man 

 ftands while at work. He commences his operations by 

 fifting a layer of charcoal over the bottom of the pot, about 

 half an inch thick, and he is careful in ufing the fieve to lay the 

 charcoal of an even thicknefs in every part ; but if it (hould 

 not be carefully done, he levels it with the (hovel. The work- 

 man on the outfide now introduces the bars into the furnace 

 through a hole, made by taking out a brick in the wall, juft 

 over the end of one of the pots, and the workman within 

 depofits them upon the ftratum of charcoal in the bottom of 

 the pot, arranging them parallel to each other, and leaving an 

 interval of about an inch between each bar. When the 

 bottom of the pot is in this manner covered with iron bars, 

 charcoal is again fifted upon them, and levelled with the 

 fliovel, to fill up the intermediate fpaces between the bars, 

 and to cover them about an inch thick : another layer of 

 bars is then introduced into the furnace, placed upon the 

 charcoal, and in its turn covered over with a ftratum of char- 

 coal ; and in this manner the pot is filled to within two inches 

 of the top. A layer of the fand which is found in the 

 bottom of grindilone troughs, is then fpread three or four 

 inches thick upon the whole, to cover the pots up clofe, and 

 prevent the accefs of the common air and flame. In placing 

 the fucceffive layers of bars in the pot, it is proper that each 

 (hould be laid over the fpace between two of the bars in the 

 layer beneath, becaufe each bar will then be furrounded by 

 a greater thicknefs of charcoal, than it would if they were 

 laid direftly over each other. Two or three of the bars 

 (hould be left fomiewhat longer than the reft, and their ends 

 (hould projeft through the trial-holes in the ends of the pots, 

 and fand rammed round them in the holes to keep out the air. 



The pots being both filled and covered up with the fand 

 and rammed down, the holes for introducing the bars are 

 clofed by a brick or fire-ftone, and luted with fire-clay. The 

 apertures through the outer wall oppofite the ends of the 

 trial-holes are alfo ftopped and luted. The iron plate upon 

 which the man ftood is now removed, and the doors in the 

 vault clofed up by bricks fet with fire-clay ; next, the opening 

 in the external building is (hut up, and the furnace is charged 

 ready for lighting. 



The furnac-e is kindled by lighted wood placed on the 

 fire-grate, then a few coals are thrown in, and when well 

 lighted, the quantity is increafed ; the heat thus generated 

 rarefies the air contained in the vault and in the great cone ; 



and 



