76 CONSTRUCTION OF RETORTS. 



about an inch in diameter, can be fixed, and led into any open retort. The 

 main pipe is connected with a blowing cylinder, worked by the steam-engine, 

 so that a strong blast can be made to impinge upon any part of the hard in- 

 crustation, which gradually yields to it, and may then be removed without 

 difficulty. 



PLATE III. 



EAR-SHAPED RETORT. 



As an example of an " ear-shaped " retort, I have taken those which were 

 at work at Mr. Clegg's iron-works near Liverpool. 



Fig. 1 . is a front elevation of a bench containing three retorts. 



Fig. 2. is a section taken transversely. 



Fig. 3. is a longitudinal section through the centre of the arch. 



Fig. 4. is a plan through A B in Fig. 2. 



Figs. 5, 6 and 7 are views of a mouth-piece on a scale of an inch to a foot, 

 which will show the method usually adopted for securing the lid in all ordi- 

 nary retorts ; this plan I do not think has been at all improved since Mr. 

 Murdoch first used it in 1805 ; and as it is simple and effective, I see no 

 reason why it should be altered. There may have been a solitary instance of 

 alteration for the sake of having something new, such as the bar through which 

 the screw passes being made to turn on a hinge at one end, and secured by a 

 latch at the other, or the screw made to act on one side of the retort mouth, 

 etc. but none of these plans are so cheap or durable as the old one. 



The great objection to the ear-shaped retort is, that the bottom bends are 

 liable to become filled up with hard carbon, and when that is the case they are 

 sure to crack. The principle on which they are constructed is good ; and if 

 they could be charged properly, viz. with a stratum of coal from 3 to 3 inches 

 thick, evenly spread over the bottom, they would be found to make more and 

 better gas than York Ds and circular retorts (where the stratum of coal is 

 thicker), simply because it would be more evenly acted upon. In all cases, with 

 the same degree of heat, the thinner the stratum of coal the better the gas. 



The mode of setting these retorts may be precisely similar to that explained 

 in Plates I. and II. 



