ho Defcrlptlon of a Thrce-blaji Fujing Furn.ice, 



on the converfion of forged iron into call fteel, which were 

 attended with full rLiccefs. 



Cheinills who have feen this furnace feetned defirous of 

 being better acquainted witli the coiiftruiSlion of it: thp 

 .council even tranfmitted drawinj^s of it to feveral perfons; 

 and what lias hitherto prevented a defcriptifin of it fropi 

 being given was a dcfire to afcertain its power by longer ufe. 



I iong ago conceived the idea of a fufing furnace, in which 

 thf wind was diflributed in three tuyeres placed in its cir- 

 cumference, ar.d at equal dillances from each other ; but I 

 had no opportunity of realizing this idea till I became at- 

 tached to the council of mines. 



Nearly feven vears ago a plan was in agitation for con- 

 J[lru6lii)g in the laboratory of the fchool a fufing furnace 

 capable of producing a very great degree of heat, in order to 

 operate with facility and fpeed on larger (juanlities of mineral, 

 and conlequently to obtain n)ore prccifion in the trials which 

 might be made than had been obtained bv the imall furnaces 

 before employed for docimaftic experiments, 



I prppoled my ideas : they were approved by the council 

 of mines ; and I was ordered to caufe the furnace I ani 

 aboiit to defcribe to be confh'ufled. The principal difference 

 between it and thofe before ufed for the fame purpofe is, 

 that in the prefent one the wind is introduced througl; three 

 tuyeres, placed at equal diftances from each other in its cir-t 

 cumferencc, whereas in common furnaces it enters only by 

 one. 



This furnace is round, both outfide and infide, and con- 

 ftru6led of very refractory bricks, fecured by iron hoops h\ 

 fuch a manner that they cannot be difplaced. It reits on a, 

 jquare bafe of ftrong mafbn-work, raifcd to a fufhcient height 

 above tlie ground to render it eafy to manage. 



The bellows are four feet in length, and the mean breadth 

 of them IS about 20 or 21 inches : they are of wood, and 

 the joints are covered with white leather. T he upper part 

 confids of five folds and two half folds; the inferior, of two 

 folds and two half folds. They are placed 8 or 9 feet* 

 above a wooden box, the joints of which are covered with 

 leather, and into which the wind as it comes from the bel- 

 lows is convened by a copper pipe, three .nches in diameter, 

 adjufted to the upper part of the box. The box itfelf is fup- 

 porled by two iron bars built into the wall. From the lower 

 part of this box defcend, in a vertical direcSlion, three pipes 



■^ This height is arbitrary j it depends in part on the manner in wlifch 

 the bell' V. s nre difpofed, and on the height cf the chamber in which the' 

 furnace is placed. 



of 



