GAS-METER 



609 



supply of gas, and the motion of the chambers being communicated to clockwork, 

 the consumption of gas is registered upon dials in the usual manner. 



1070 



1071 



The dry meter invented by 

 Messrs. Croll and Richards is su- 

 perior in construction and accuracy 

 of measurement to that of De- 

 fries. It is shown in figs. 1070, 

 1071, and 1072. AA,^. 1070, is 

 a cylindrical case, divided into two 

 cylindrical compartments by the 

 inflexible metallic diaphragm B. 

 These compartments are closed at 

 opposite ends by the metal discs 

 c c. The latter perform the func- 

 tions of pistons, and are retained 

 in their proper position by uni- 

 versal joints attached to each. 

 The discs are restrained from 

 moving through more than a fixed 

 space by metallic arms and rods, 

 shown in fig. 1072, and when this 

 space has been once adjusted, it 

 cannot afterwards vary. It will 

 be seen that the principle of this 

 meter is that of a piston moving 

 in a cylinder; but, in order to 

 avoid the friction which such an 

 arrangement would cause if lite- 

 rally carried out, bands of leather, 

 D D, are attached, which act as 

 hinges, and allow of the motion of 

 the discs without friction. 



The gas enters the cylinder from 

 the upper space containing the 

 levers, valves, &c., fig. 1072 ; its 

 pressure forces the discs forward 

 through the space limited, as 

 above described. The flow of gas 

 is then reversed ; that is, a pas- 

 sage to the burners is opened from 

 the internal space, whilst the sup-[ 

 ply is now directed into the outer! 



VOL, H, 



1072 



