BURNERS. 197 



vantage in point of ceconomy to be derived from using these instruments will 

 be most decidedly experienced. 



Many cotton-mills are provided with a check-cock on each floor to reduce the 

 pressure in the pipes of supply ; this, if strictly attended to, will prevent an 

 improvident waste of gas as long as the pressure remains the same ; but when- 

 ever any other mills or consumers supplied from the same street-main light 

 up after the mills in question, or stop sooner, the pressure will be respectively 

 lessened or increased ; and unless the cocks are altered at each change, either 

 a deficiency of light or an excess of pressure, and consequently an extra con- 

 sumption of gas, will invariably follow. 



