76 CONSTRUCTION AND MANAGEMENT OF SMALL GASWORKS. 



tolerated. There must be something radically wrong with 

 the design, or with the system of working, to let the setting 

 get in such a state as to call for a violent remedy of this 

 kind, which not only moves the obstruction but strains the 

 arch and the end walls. All excess of draught should be 

 carefully avoided, by adjusting the dampers to give the heat 

 required, and no more. 



Neglect of these simple precautions means that the retorts 

 and the settings get into bad condition at what ought to be 

 an early period in their working life. A frequent cause of 

 bad working results is that the retorts are in bad condition, 

 and that more on account of neglect than of age. It is a 

 mistake to try to get too long a working life out of the 

 setting, and some of the ingenuity devoted towards patching 

 cracks or weak places might well have been directed, at an 

 earlier period, to the preservation of the retorts and settings 

 in good condition. A setting that, of necessity, has to be 

 banked at night cannot, under any circumstances, give so 

 long a working life as one that is run continuously, nor can 

 it have the careful and systematic working that is possible 

 when the men have no duties other than those connected 

 with the retort house, and are under the watchful eye oi 

 a head stoker or foreman. The arches and side walls are, 

 as a rule, not so strong and substantial as those in larger 

 works. But soundness and absence of leakage of air into 

 the setting is just as important in small beds as in large 

 ones, so far as economy of fuel is concerned. The arches 

 and side walls should never comprise less than 9 inches 

 thickness of fire-brick set in fire-clay, and every time the 

 bed is renewed the arch and side walls should be care- 

 fully repaired and made good. 



With regard to the weight of each charge and the con- 

 sequent yield of gas, some judgment is necessary, according 



