408 



Lord Rayleigh. The Influence of 



[Mar. 13, 



differences of electrification due either to irregularities in the drops or 

 to differences of situation, and is at first difficult of acceptance in view 

 of the efficiency of such very feeble electric forces. Fortunately I am 

 able to bring forward additional evidence bearing upon this point. 



When two horizontal jets issue from neighbouring holes in a thin 

 plate, they come into collision for a reason that I need not now stop 

 to explain, and after contact they frequently rebound from one 

 another without amalgamation. This observation, which I suppose 

 must have been made before, allowed me to investigate the effect of a 

 passage of electricity across two contiguous water surfaces. The jets 

 that I employed were of about -V inch in diameter, and issued under 

 a moderate pressure (5 or 6 inches) from a large stoneware vessel. 

 Below the place of rebound, but above that of resolution into drops, 

 was placed a piece of insulated tin plate in connexion with a length 

 of gutta-percha-covered wire. The source of electricity was a very 

 feebly excited electrophorous, whose cover was brought into contact 

 with the free end of the insulated wire. When both jets played upon 

 the tin plate, the contact of the electrified cover had no effect in 

 determining the union, but when only one jet washed the plate, union 

 instantly followed the communication of electricity, and this notwith- 

 standing that the jets were already in communication through the 

 vessel. The quantity of electricity required is so small that the cover 

 would act three or even four times without being re-charged, although 

 no precautions were taken to insulate the reservoir. 



In subsequent experiments the colliding jets, about inch in 



diameter, issued horizontally from similar glass nozzles, formed by 

 drawing out a piece of glass tubing and dividing it with a file at the 

 narrowest part. One jet was supplied from the tap, and the other 

 from the stoneware bottle placed upon an insulating stool. The sen- 

 sitiveness to electricity was extraordinary. A piece of rubbed gutta- 

 percha brought near the insulated bottle at once determined the 

 coalescence of the jets. The influencing body being held still, it was 

 possible to cause the jets again to rebound from one another, and then 

 a small motion of the influencing body to or from the bottle again 

 induced coalescence, but a lateral motion without effect. If an 

 insulated wire be in connexion with the contents of the bottle, similar 

 effects are produced when the electrified body is moved in the neigh- 

 bourhood of the free end of the wire. With care it is possible to 

 bring the electrified body into the neighbourhood of the free end of 

 the wire so slowly that no effect is produced ; a sudden movement of 

 withdrawal will then usually determine the coalescence. 



Hitherto statical electricity has been spoken of ; but the electro- 

 motive force of even a single Grove cell is sufficient to produce these 

 phenomena, though not with the same certainty. For this purpose 

 one pole is connected through a contact key with the interior of the 



