7* De/criptlon of a Three-hlaJ! Fiijing Furnace. 



kept at about nine inches, the height of the bricks : thefe 

 bars are pierced with holes towards the end riveted on the 

 circles,- and placed at equal dillances on their circumference. 

 One of the extremes of each of thefe three bars is left of a 

 futiicient length to pafs beyond the lower circle about aa 

 inch, in order to make them enter into three holes forfned in 

 the brick- work which forms the bottom of the furnace, and 

 by thele means to prevent tlie furnace from becoming de-» 

 ranged. 



This kind of iron frame was filled with bricks fimilar to 

 thofe employed for the bottom of the furnace : ihcy were 

 rubbed one on the other to fmooth them, and the corners 

 were a little rounded; fo that, being placed upright with their 

 broad fides applied to the iron hoops, the narrow fide fl:ood 

 inwards. By thefe means all thefe bricks were adjufted ia 

 fuch a manner as to touch each other by their broadeft faces, 

 and to form the fides of the furnace, the thicknefs of which, 

 was equal to the breadth of the bricks, and its depth to their 

 length. Three apertures were referved for the tuyeres which 

 terminate the three tubes that convey the wind, by cutting 

 from as many bricks a portion equal to the thicknefs of a 

 brick. 



Thefe bricks thus adjufted were taken from the iron frame, 

 and then replaced, putting between them a cement to con- 

 ne<3: them firmly and to fill up the joints. The duft pro- 

 duced by cutting the bricks was referved for this purpofe ; 

 and I defired the workman to mix with it a fmall quantity of 

 clav diluted in a great deal of water, in order to make a puddle 

 for daubing over the bricks, and in particular to put between 

 them no more than was neceffary for filling the joints and 

 the fmall fpace left between their faces in confequence of 

 any inequality left in dreffing them. 



The furnace thus confl;ruded was then placed on its bafe, 

 a firatum of the fame mortar employed for filling up the 

 joinings of the bricks being firfi: interpoied. The extremities 

 of the three iron bars projecting beyond the lower circle were 

 placed in the holes left in the bafe to receive them. The 

 body of the furnace encircled with iron, both by its weiaht 

 and the gentle blows given to the iron hoops above the bars 

 which connected them, expelled the excefsof the mortar, and 

 caufed a part of it to enter and unite with that which filled 

 up the joints of the brick-work of the circumference, which 

 rendered it immoveable. 



The bellows is fecured as iifual by crutches of iron and 



fupporters fixed in the wall and to the floor : the handle is 



vliipoled in fuch a manner, that the rope which makes it a6l 



9 may 



