Royal Society. 391 



RP 2 



would be proportional to the consumption of zinc, and de- 

 note an action which depends only on the consumption. What- 

 ever be the internal process in the motor and conductor, the 

 action perceived is quantitatively viewed as if a motor had ex- 

 erted an impact on the conductor and both had behaved like 

 completely inelastic bodies. Something in common both pro- 

 cesses must have; and this testifies strongly to the actual presence 

 of a vis viva, and of an acceleration whereby, owing to the resist- 

 ance, the accelerated motion would soon be constant. The pre- 

 ceding seems to indicate that an increase of cells produces more 

 powerful impacts, while an increase of the plates increases the 

 quickness of their succession but not the intensity of the indi- 

 vidual impulses, so that there would be an analogy to red and 

 violet light. So long, however, as there are no further reasons, 

 this notion remains a rather vague hypothesis. 



LII. Proceedings of Learned Societies, 



ROYAL SOCIETY. 

 [Continued from p. 316.] 



June 20, 1867. — Lieut. -General Sabine, President, in the Chair. 



HPHE following communication was read : — 

 *■- " On a Self-acting Apparatus for multiplying and maintaining 

 Electric Charges, with applications to illustrate the Voltaic Theory." 

 By Sir William Thomson, F.R.S. 



In explaining the water- dropping collector for atmospheric elec- 

 tricity, in a lecture in the Royal Institution in I860, I pointed 

 out how, by disinsulating the water-jar and collecting the drops 

 in an insulated vessel, a self-acting electric condenser is obtained. 

 If, owing to electrified bodies in the neighbourhood, the potential 

 in the air round the place w r here the stream breaks into drops is 

 positive, the drops fall away negatively electrified ; or, vice versa, if 

 the air potential is negative, the drops fall away positively elec- 

 trified. The stream of water descending does not in any way de- 

 tract from the charges of the electrified bodies to which its elec- 

 tric action is due, provided always these bodies are kept properly 

 nsulated ; but by the dynamical energy of fluid-motion, and work 

 performed by gravity upon the descending drops, electricity may 

 be unceasingly produced on the same principle as by the elec- 

 trophorus. But, as in the electrophorus there was no provision 

 except good insulation for maintaining the charge of the electrified 

 >ody or bodies from which the induction originates, this want is 

 supplied by the following reciprocal arrangement, in which the 

 body charged by the drops of water is made the inductor for an- 



