48 MR. DANIELL ON VOLTAIC COMBINATIONS. 



The index was steady for a short time, but began slowly to decline in each instance 

 for about 10°. Upon agitation of the ball in the solution it always rose to its pre- 

 vious amount. 



Upon repeating the experiment and keeping the ball always agitated^ the following 

 results were obtained : — 



Ball at the top .40 



Ball at the centre 42 



Ball at the bottom ..... 42 



Another repetition gave 



Ball at the top 45 



Ball at the centre . . . . . 46 



Ball at the bottom 44 



The index always fell when the ball was not agitated^ and the decline may probably 

 be ascribed to a change in the saturation of the liquid in immediate contact with the 

 ball, which agitation prevented by keeping the solution in an uniform state. 



I now separated the hemisphere and experimented with the lower one alone. The 

 results were as follow : — 



Ball at the top 35 



Ball at the bottom 80 



Ball at the top 35 



Ball half-way between .... 60 



When the ball was placed at the centre of the surface and at the sides almost in 

 contact with the hemisphere, the index rose to 36° in all the three positions. 



Hence it appears that the same law was maintained; although the force which cir- 

 culated was reduced to one half of the amount of that from the first combination. 



Before I venture to offer two or three remarks upon this difference, I shall proceed 

 to lay before you the results of some experiments upon combinations of generating 

 and conducting surfaces of other forms, commencing with the cylindrical as ap- 

 proaching in simplicity to the splierical, and for the purpose of connecting my ob- 

 servations with that form which I have found most practically advantageous in the 

 construction of my battery. 



J took one of the cells of the small battery*, six inches in height and eleven inches 

 in circumference, charged in the usual way, and found that the single zinc ball of one 

 inch diameter, produced with it a deflection of the magnetic galvanometer of 55°. 

 Two similar balls only increased the deflection to 60°, and its own rod, six inches in 

 length and f inch diameter, did not increase the effect. These were exactly the same 

 amounts as were produced by the same generating surfaces in the brass sphere. 



An amalgamated zinc cell of exactly the same dimensions, charged with the di- 



* Philosophical Transactions, 1836, p. 117. 



