44 MR. DANIELL ON VOLTAIC COMBINATIONS. 



with which the conducting- wires were brought into contact, and towards which the 

 force diffused over the sphere must have converged, than at any other point ; proving 

 that the force must have diverged from the centre equally through the electrolyte, and 

 could only have drawn towards the conducting wires in the conducting sphere itself. 



I now destroyed the insulation of the two hemispheres by fixing to the lower one 

 a thin ring of brass, which came in contact with the upper when wedged down in its 

 position by the means already described. The sphere, thus in good metallic commu- 

 nication in every part, was charged as before ; the precipitated copper having been 

 previously cleaned off by a little nitric acid and rotten-stone. The deviation of the 

 galvanometer was 55°, and it was perfectly steady, whatever number of connexions 

 were made with the sphere, or at whatever point the circuit was completed. It made 

 no difference in the amount of the force which circulated, whether the contact with 

 the brass was made as near as possible to the zinc conducting wire, or at the point 

 the farthest removed from it. 



I next proceeded to ascertain what would be the effect of increasing the surface of 

 the generating metal. For this purpose two amalgamated zinc balls of the same 

 diameter as before were placed in contact upon a varnished wire, and substituted for 

 the single ball in the centre of the sphere : the deviation of the galvanometer only 

 increased 5°, rising from 55° to 60°. Upon replacing the single ball it fell again to 

 55°, and so alternately rose and fell to tlie same amount upon frequent repetitions of 

 the change. An amalgamated zinc rod six inches in length, and ^ inch in diameter, 

 was then substituted for the balls, but the deviation did not rise higher than 60°. 

 Thus the generating surface was increased from about three square inches to six and 

 9*4 with very little increased effect. 



These experiments were all made with the generating metal placed as nearly as 

 possible in the centre of the conducting sphere : this position was now changed, and 

 sometimes the zinc ball was placed at the bottom of the membrane almost in contact 

 with the sphere ; sometimes it was drawn up nearly to the top ; again it was placed 

 in the centre ; but none of these changes produced any appreciable alteration in the 

 deviation of the needle, the galvanometer constantly indicating 55°. 



From this I was led to consider (although I am quite aware that the measures may 

 not have been sufficiently accurate to determine the point with precision,) whether 

 the force emanating from the zinc ball might not diffuse itself over the surrounding 

 conducting sphere in obedience to the well-known law of radiant forces of the inverse 

 square of the distance ; since, although the cases may be dissimilar, according to this 

 law an attractive point placed within a hollow sphere of attractive matter remains in 

 equilibrio, whatever its position may be. Or the analogy, perhaps, is stronger of 

 light diffusing itself from a luminous point within the sphere in the same relative po- 

 sitions as those of the generating ball. 



This conclusion, if correct, appearing to me to be of great importance, I was de- 

 sirous of confirming it by repetition and variations of the experiment. 



