﻿Electricity on Streams of Water Drops. 155 



collisions between neighbouring drops. The case seems to be 

 somewhat analogous to that o£ a waterfall which is partially 

 broken up into drops as it falls, the direction o£ motion of the 

 resulting drops being greatly influenced by the friction of 

 the air and accidental vibrations or currents in the air. 

 Fig. 1 gives evidence o£ collisions breaking large drops into 

 small ones which will follow somewhat erratic courses. 

 When collisions do occur in such a stream, the tendency to 

 break the drops into smaller ones must be greater than any 

 tendency towards coalescence, as capillary action will not 

 come into play until the opposing surfaces are extremely 

 close. 



How T ever, when we turn to the cases of the streams of 

 charged drops, we have to deal with the extremely complicated 

 problem of the interaction of charged spheres at various 

 distances from one another. In these cases we have three 

 outstanding facts, (1) the alignment of the stream of charged 

 drops, (2) the coalescence of charged drops under certain 

 circumstances, and (3) the scattering and possible splitting 

 up of charged drops under other circumstances. 



One suggested explanation for the alignment, of the 

 charged drops was the force exerted by the charged ring 

 itself on a drop not on the central axis of the cylindrical 

 inductor. The resultant value of the force of the ring on the 

 drop will urge the drop to take a path along the axis. 

 However, when instead of the charged ring one uses a 

 rubbed ebonite paddle the same phenomenon is noticeable, 

 although the force towards an axis does not exist. Again, 

 the stream taken from an insulated bottle was charged 

 directly by joining it up with the pole of a battery and 

 similar results followed. That is the alignment is undoubtedly 

 a result of the charges possessed by the drops. 



Again, the alignment cannot be due to the coalescence of 

 the drops on collision, as a comparison of figs. 4, 5, 9 a, 9 b, 

 and 9 c will show. The small and large drops in the latter 

 two cases are absolutely aligned before either coalescence or 

 dissipation comes into question. 



There remains then the outstanding problem of the inter- 

 action of two spheres charged with electricity of the same 

 sign. Elementary consideration of the electrostatic problem 

 tells us at once that the action is not always repulsion except 

 in the single case of equal and similar bodies being charged 

 with equal and similar quantities of electricity. In every 

 other case, although the charges may be of the same sign, the 

 question of whether we have attraction or repulsion depends 

 on the ratio of the charges on the bodies, say spheres, the 



