164 Description of Mr. Arthur Woolf^s Steam- Valve, 



As this pressure then remains constant, the experiment 

 will be mo're determinate, and consequently more com-' 

 parative. 



The application of this piston to the boilers of steam en- 

 gines needs no further explanation, except that, in thi* 

 case, the diameter of the piston must be considerably in- 

 creased. It seems here to offer the same advantage oi 

 greater uniformity in the force of the steam, especially it 

 the motion of the piston be empk)\ed to regulate the fire 

 of the furnace, and to prevent the useless dispersion of the 

 vapour, by preventing an excess of intensity in the fire. 

 Fov this purpose, the following apparatus may be used. 

 Let in, n, fig. 3- be the aperture of the conduit for the cur- 

 rent of air which maintains the combustion of the fuel, 

 and o,p, a register; which, by rising or falling, opens or 

 shuts that cotiduit. If the motion of the safety piston bt 

 combined by any means with the register, in such a man- 

 ner that, when the former ascends, the latter descends, so 

 that when the piston is at its greatest elevation tUp register 

 shall be entirely shut; it is evident, that, since the heat pro- 

 duced depends on the access of the air, the elasticity of the 

 vapour being determined by the weight of the piston, will 

 not only remain within the boimds prescribed for it, but 

 will regulate itself, by preventing more air from entering, 

 into the furnace than is necessary to maintain its force. 



I do not know what obstacles may occur in the applica- 

 tion of this apparatus on a large scale; but it seems to pro- 

 mise a greater saving of fuel, since, instead of throwing out 

 to no purpose a superahundant quantity of vapour, it wift 

 prevent its production, without expending any considerable 

 part of the force of the machine for that purpose. 



XXVI. Description of ?Jr, Arthur Woolf's 



Sicani-P'alue. 



Xn our last we laid before our readers an account of Mr. 

 Woolf's newly invented boiler, in which we mentioned 

 that, besides employing safety-valves, he had introduced a 

 valve of a new construction to regulate the quantity and 

 power of the steam passing from the boiler. We shall now 

 lay before them a description of this ingenious contrivance.. 

 A (Plate f\'.) is a part of the main cylinder of one of 

 Mr. Woolf's boilers ; 13 B the neck or outlet for the steanr, 

 ^unnouiitcd by tiie steam-b'jx C, which i.- joined to the neck 



■ BBCiy 



