IRON. 



145 



There are four small tubes, a b, a' b', fixed into the 

 extremities of these long pipes, A B, A' B', as may 

 be seen more particularly in the ground plan, fig. 3. 

 It is necessary to attend to the manner in which 

 these pipes are fitted into each other, as the joinings 

 must be made perfectly air-tight and strong. This 

 is effected in the following manner: The extremi- 

 ties of the great pipes, A B, A' B', are formed into 

 frustums of cones, the smaller parts of which are at 

 the extremities, curbs being placed within at the 

 bases. The little pipes are made to terminate in 

 conical swellings, the base of each being at the very 

 extremity, but of such a magnitude that it may be 

 introduced into the end of the large pipe, and be 

 pressed against the curb. The space between the 

 conical end of the large pipe, and the swelling of the 

 small one is filled with mastich, in which way the 

 joint is firmly secured. The bent pipes, D S D', are 

 fixed in a similar way. The construction of the fur- 

 nace is altogether analogous to the reverberatory 

 kind, as will be seen by inspecting fig. 2. The walls 

 are formed of common brick, but fire bricks are em- 

 ployed for the vault. In order to give sufficient 

 strength to the building, the walls are bound by ten 

 cast iron pillars, F F, bound together by beams, en- 

 closed in the brickwork, as may be seen at fig. 2, and 

 each end is likewise furnished with four similar sup- 

 ports. The fuel is thrown upon the grating G, 

 through the door H, the air which supports the com- 

 bustion entering from K, the ashpit below. The 

 smoke from the fire proceeds up by the inclined 

 back I, and rising strikes the bent pipes, which 

 stretch across the vault. It will be easily seen that 

 in this way the last of the bent pipes receive more 

 heat from the smoke than the first, but this is com- 

 pensated for by the form and position of the vault 

 and the bottom, which cause much more of the heat 

 to be radiated to the first tubes, both from the fire 

 and from the vault. The flame and smoke having 

 acted on the bent pipes, pass through the opening 

 L, and from thence into the chimney. In order to 

 save the joinings of the bended tubes, D S D', with 

 the large tubes, A B, A' B', a wall of brick proceeds 

 along the whole length of the furnace, on each side 

 of the fire, and between that and each large pipe, 

 built in such a way as to protect the joinings. The 

 manner of operating is simply this : The air from 

 the blowing engine is propelled with the requisite 

 force into the pipe A' B', through the extremity, and 

 passing through all the eight bent pipes D S D', 

 passes through the large pipe A B, through its ex- 

 tremity 6, and by means of the connecting pipe into 

 the furnace, where the smelting is effected. The 

 pipes D S D', being kept at a red heat, it must fol- 

 low that the air must enter the smelting furnace, at 

 a temperature very much higher than when it was 

 propelled from the blowing engine. 



The inventor has given the dimensions of an ap- 

 paratus, such as we have described, calculated to 

 supply a furnace with 800 cubic feet of air per 

 minute. The dimensions of the horizontal pipes A B 

 A'B' 



Length 



Exterior diameter 



Interior do. 



Peot. 



12008 



1-1808 



0-99 



Dimensions of the four pipes a b, a' b'* 



Length 



Exterior diameter 



Interior do. . 



3-94 



0-79 



0-65(5 



Dimensions of the eight bent pipes D S D' 



Exterior diameter 

 Interior do. 

 Length of the axis 



0-558 

 0-380 

 901 



Weight of the various pipes 



Lbs. 

 332956 



2848-86 



The two pipes A B A' B ', 

 Thu eight bent pipes, 

 The eighteen supports 



Giate, bolts, and door, . . 5358-15 

 We will now describe the structure of the ap- 

 paratus for heating the blast by means of the smelt- 

 ing furnace itself. The furnace is represented in 

 section, in the wood engraving, below. This acts on 

 Fig. 4. 



the same principle as that just described, the chief 

 difference being in the manner in which the heat is 

 obtained. The reverberatory furnace, with its sys- 

 tem of horizontal and bended pipes, is placed on the 

 top of the chimney of the smelting furnace, and the 

 heated air and smoke from the large furnace enters 

 the small furnace just where the grating was placed 

 in the former construction. It may be remarked that 

 the three first bended pipes are directly above the 

 flues of the smelting furnace, and therefore receive 

 the first action of the flame and smoke, which are re- 

 flected again by the vault, before entering the chim- 

 ney, which is here made to rise directly from the end 

 of the vault, instead of communicating by a horizon- 

 tal pipe, as in the former construction. The distance 

 of the large horizontal pipes is somewhat greater than 

 the diameter of the flue f. e., the chimney of the smelt- 

 ing furnace, in consequence of which the furnace is 

 fed through the opening N. The communication be- 

 tween the heating apparatus and the blowing engine 

 is similar to that formerly described, but the heated 

 air passes out of the system of pipes at the top of the 

 smelting furnaces, and is propelled into the tweers, 

 which are seen entering at the bottom, through two 

 pipes, which are led down the exterior wall of the 

 furnace, as may be seen on inspection of the figure. 

 The furnace we have just described, is better cal- 

 culated for smelting by charcoal than by coke, as the 

 heat raised by the former is much greater than by the 

 latter. 



In order to complete the description of the appar- 

 atus with hot air invented by Mr Neilson, it remains 

 for us to describe the system of heating, which is 

 employed in Wilkinson's foundery, in the cupolas 

 intended to melt the metal. This application of Mr 

 Neilson's invention is due to Mr Taylor. Various 

 other applications of the hot air blast have been 

 recently made by Schauffelen, of Wurtemburg, who 

 causes the air to pass through a sort of syphon in the 

 chimney, before it reaches the grate. 



