negative charge to the funnel b. This produces a small increase in the negative charge on the inducing cylinder B. The drops of water falling through B are positively electrified, and on striking the funnel a give up their charge to it, which accession of charge is conveyed to the inducing cylinder A, making it more efficient for charging the drops of water which pass through its interior. We have thus a cumulative action between the inducing cylinders, the drops of water and the collecting funnels. The limit of this cumulative process is reached when the dispersion of charge, due to the growing potential difference, just balances the accession of charge carried by the drops of water from one inducing cylinder to the other. We have here a case of electrification by mechanical means, namely, the motion of drops of water. The energy represented by the electric field between A and B is derived from falling water.
The use of water in an apparatus for producing electrification is not always convenient, and under certain circumstances, as, for instance, on board, ship, quite impossible, because in a sea-way the drops would not fall plumb into the collecting funnels. But it is precisely in submarine telegraphy generally,
