ON FURNACES. 385 



a large damper or partition is fixed between the compartments No. I 

 and No. 12. Thus the air entering through the open doorways of 

 No. i and No. 2 has to make the entire circuit of the kiln, before it 

 escapes, through the flue leading from No. 12, to the common chimney. 

 In the course of this circuit, it passes first among bricks almost cold, 

 and takes up their heat, and then goes forward to warmer bricks, and 

 then to hotter and hotter, carrying the heat of the cooling bricks for- 

 ward with it, until it reaches the part of the ring diametrically opposite 

 to the two open and cold compartments. At this place it gets a final 

 accession of heat, from the burning of a small quantity of coal dust, 

 which is dropped in among the bricks, from time to time, through 

 numerous small openings furnished with air-tight moveable lids. 

 Thus, at this part of the kiln, there is generated the full intensity of 

 heat which is required for burning the bricks. The products of com- 

 bustion then pass forward to the bricks not yet burned, which are thus 

 heated by their continuous current, and so from the hottest bricks to 

 those that are less and less hot, heating them as they go, and thence 

 to those that are still damp, drying them as they go ; and thence they 

 pass finally to the chimney, in a state almost cold, and loaded with 

 moisture from the damp bricks. 



On the following day, the partition is removed from between the 

 compartments Nos. 12 and i, and placed between Nos. I and 2; the 

 compartment No. i having been by this time filled with fresh damp 

 bricks, and its doorway built up. The damper in the flue leading from 

 No. 1 2 compartment to the chimneyis shut, and that from No. i is opened. 

 No. 2 compartment being now empty is refilled with unburned bricks ; 

 and the removal of cold burned bricks from No. 3 is commenced. 

 The place where the small coal for fuel is thrown in is also advanced 

 round the circle by one compartment ; and the products of combustion, 

 at the end of their circuit in the annular chamber, and just before their 

 escape to the chimney, now pass among the fresh bricks that were 

 built in on the day before ; and so the process goes on, just as on 

 the previous day ; and the fire makes a complete circuit of the kiln 

 in twelve working days. 



The saving in fuel effected by thus utilizing the heat of the burned 

 gases, and of the red-hot bricks, as well as the greater part of that 



B B 



