36 



Mr. W. L. Balls. 



[Deo. 22, 



fitted to its lower end, which also served to carry the weights which 

 determined the pressure. 



Thus arranged, the gas-holder, having been freshly charged with air, and 

 having settled down to temporary equilibrium, sank into the beaker more or 



Fig. 1a. 



less rapidly according to the aperture of its exit. Having descended to 

 a certain point, with no friction to overcome excepting that of the pin- 

 bearing of the balance, it made an electric contact, which sent a? current 

 through a solenoid (S, S) surrounding the iron rod previously mentioned. 



