Regulating Valve for d Gas Establishment. 137 



of the valve, and C, another pressure gauge, also connected 

 with the main on the town side. 



" There is a burner, supplied from the town side of the valve, 

 placed before the eye of the person who adjusts the valve. 



'• From repeated inspection of the town lights at all hours 

 of the night, as well as of the burner before the index, the re- 

 quisite pressure is known and regulated ; as the night advances, 

 the valve is lowered more and more, and in the morning (when 

 the lamps ought to be all out) it is depressed to one-tenth 

 of an inch ; that being sufficient to cause the exit of the gas in 

 the lowest situations. 



*^ The operation of the valve is so well understood, that I 

 have been enabled to leave the management of it to the work- 

 men ever since its erection. 



*' By this simple, yet effectual, contrivance, the saving of 

 gas has been very great. 



, *' I have never had occasion to elevate the valve more than 

 -j2^*(jths*, as shown in the drawing, this being sufficient for the 

 escape of upwards of 7000 cubic feet of gas per hour, without 

 the pressure of the gas being reduced more than -ji^th of an 

 inch, (viz. from one inch to -j-yhs after it has passed the valve.) 



'^ I believe you are aware that, from the nature of the coal 

 used at this establishment, the retorts, after much use, become 

 lined with a hard carbonaceous substance, of so considerable 

 a thickness, as to diminish their capacity to one half and less, 

 on Avhich account a larger number of retorts u'as required ; and 

 from the imperfect conducting power of this incrustation, the 

 decomposing process was slower, and additionally expensive. 

 I am happy to inform you, that I have perfectly succeeded in 

 removing the incrust in the following way : the retorts are left 

 open, and kept at a good heat, by which the carbonaceous 

 lining undergoes slow combustion, and in the course of a week, 

 or more, according to the thickness, it is entirely burnt away. 

 ^' Believe me to be. Sir, 



" Very respectfully yours, 



" W. H. Eastwick." 

 '* To R. AddamSy Esq" 



t When the area of thelunaric aperture is]= 14.733 square inches. R. A, 



