Befmption of a Three-Uafl Fujtng Furnace. 75 



fcrves it as a boUom. OP, luafonry which ferves to fupport 

 the three pipes that convey the wind to the furnace. X YZ, 

 fig, %. are the three ctK'ks fixed to the three pipes which pro- 

 ceed from the box to convey the wind to the furnace. 



In ti"-. 4., tlie dinienfions of which are double thofe of 

 ficr. 2., may be feen the details of one of thefe cocks. 



°y\t r, Sy t, the body of the cock is km in front ; the ftnpper 

 bejjvi; takeji out {hows af r and at t the two holes which le^ 

 ^piv<r^he tv^bies that coinniunicate either with the box or a iih 

 the tuveres. u exhibit.-^ the body of ihe cock fcea on one iide ; 

 <i/ the key wnii its aperture x, and its head ;c. Tiiis key, 

 tprned nmnd more or iels in its focket, lerv-s to give more 

 or lefs wind. 1,3.3? >'""" '^''P* which fecure the cocks at 

 the difcancp they ought to be from each other, an(l co^mect 

 them at the fame time to the iron crunches whicii fupport 

 the air-box. ^ 



Ficr. 5. a plan of thefe two clips. They are bent at the 

 places marked 1, 2, 3, to embrace ihe body of the three cocks, 

 and fecure them in fuch a manner that they cannot be dc-. 

 ransred when thev are opened or (hut. 



Ficr. 6 and 7 reprefcut the plane and feclion of the changes 

 and additions propofed to be made when the furnace i? le- 

 tonftruded. At I, L, and N, are feen the extremities of the 

 three pipes that enter the forged iron tuyere-;, and convey t!)e 

 wind to the interior of the fucnace. a, by aiid r, indicate the 

 thickncfs at the upper pari of each of ihe nnifiis and of the 

 bod'- of the furnace, between svhicb there arc two vacuities 

 filled with pounded glafs or fome other bad conductor of heat. 

 d, the erate on which are dcporited the relts of baked earth 

 deltmed to receive the crucibles. (, the crucible, luted and 

 attached >vith clay to a reft of leaked earth. 



Note by the Author on the Furnaces which have fever al 

 'I'uycres. 



The advantage arifing in large founderles from the appli* 

 cation of two or thre? tuyeres inliead of one, is well known ; 

 but I do not; I)elieve that fuch an arrangement was ever 

 adopted in Imall furnaces. 



AlTrcibjivh, in C'arinthia, C. Le Fcbre, and TJaflcnfratz 

 member of tjie council and infpeftor of mines, ,faw, about 

 twenty years ago, a la'ge luriuce with two tuyercg; drawings 

 of which tliey' brouiihl to France, and which they repre- 

 fcDted in tl]e third pU;e nf I'/lri de J'abriquer /rs C'l/ions, by 

 Monge : two pairs of bdlows i'upply wind through t^P oppo- 

 fiie tuyeres, and fmce Uiat arrangeiueat the daily produdl of 



inctal has been doublv. 



1(1 



