1840.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL"! 



207 



earn a Uvelihoud by supplying the city of Tabreez and adjoining towns 

 witli fuel. 



The cliarcoal is made in the following maimer: a rectangular hollow 

 is dug in the earth, about twelve feet long, six feet wide, and four 

 feet deep. The sides are formed of the natural ground, or common 

 alluvial cover ; a small sloping doorway is cut at one end. and at the 

 other a chimney is built rising to the height of about six feet. The 

 pit is filled up to the level of the ground with cut branches of all di- 

 mensions, placed horizontally and lengthways in the hollow, and are 

 covered over with earth, and secured eftectirally against the admission 

 of air, excepting by a small hole in the built-up door-way, which is 

 left open to produce a current; the heap is kindled through the small 

 opening in the door-way, and after it has burned for two or tln-ee days 

 the covering is removed, and the charcoal thus produced is then 

 stored for sale. One of these hearths will produce about one ton of 

 charcoal, which sells at thirteen shillings sterling. 



The charcoal thus produced, however, is seldom used in the manu- 

 facture of iron, the smiths preferring that prepared in the following 

 manner: the cut branches are merely laid horizontally on the surface 

 of the ground, and piled up to a considerable lieight; having been 

 lighted from beneath, they are allowed to burn in the manner of an 

 open fire, till the smoke and flame have nearly ceased ; the fire is then 

 quenched with water, when there remains a charcoal which is very 

 light, and is found to reduce the ores of iron in a much less time than 

 the heavier charcoal produced by the first method. 



As the iron is manufactured on a very small scale, a very simple 

 forge answers the purpose. It consists merelj' of a hollow hearth dug 

 out of the clay floor of the hut, about fourteen inches square in the 

 bottom, and nine inches deep, for receiving the ore and fuel ; and of 

 another hearth immediately thereto adjoining, intended to receive the 

 slag, and consisting of a larger excavation, about three inches deeper 

 than the former, and situated betwixt it and the wall at the other 

 extremity in which the chimney is constructed. A wall is built on 

 each of the two sides, two or three feet high, and the whole is covered 

 over with large stones capable of resisting the action of the fire. The 

 whole of the first or iron-hearth into which the blast is introduced is 

 left open above and at the sides ; but a low w all is built next the bel- 

 lows to prevent the heat from injuring them. The whole is afterwards 

 plastered over with clay and chopped straw, in order to maintain the 

 draught of the chimney entire. The chimney is carried up through 

 the wall of the hut, and seldom rises higher than its roof. 



The construction and dimensions of these hearths will be best ex- 

 plained by the accompanying drawings. 



Fig. 1— Vertical Si'cUon. 



Fig. 3— Su'e Vie 



^- M^lX-4^!r — ^— f-^ f 3 



Fig. 1— Ground Plan. 



The operator having carefully selected charcoal of a small size and 

 hght weight, proceeds to clear it from dust and sand with a small 

 meshed nddle, removing all the heavy pieces of charcoal or stones 

 that may be accidentally mixed with it. The raw ore being next 

 selected and mixed, and being broken into small pieces about the si/e 

 ot a hazel nut, is thoroughly moistened with water. A dam is then 

 made between the iron and slag hearths, composed of charcoal and 

 charcoal dust well rammed down, and the top is coped with iron slae 

 ....,„ , f„.„o. .„,.u,™ The following sketch will show this arrange- 



from a former smelting, 

 ment 



Fig. 7, 



References.— I. H. Iron Hearth.— S. H. Slag Hearth.— C. and D. Ch;ucoal 

 and Dust.— .S. Slag.— C. Charcoal.- O. Ore.- F. Floor. 



The Twycre pipe, which is made of white clay, and bears a violent 

 heat for a long time without melting, is then inserted through the 

 small hole in the side wall of the first iron hearth. The point of the 

 pipe is made to reach half way across the iron hearth, and within six 

 inches of the bottom, as shown in Fig. 6. A layer of charcoal, of three 

 inches thick, is then spread over the bottom of the iron hearth, and 

 upon this two other layers laid across, one directly under the Twyere 

 pipe of about six inches in breadth and three inches deep, and the 

 other at the front of the hearth of the same thickness, to correspond 

 with the overlying part of the dam. The two trenches which are thus 

 formed are filled up with the moistened ore, well rammed down. A 

 second layer of charcoal,.in a state of ignition, is thereafter laid over 

 the former under the twyere pipe, and other successive layers of 

 charcoal and ore are filled in, corresponding with those in the bottom. 



