128 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XIII.) 



charging train. The two intervals or places of discharge n and o could be varied at 

 pleasure, their extent being measured by the occasional introduction of a diagonal 

 scale. It is evident, that, as the balls A and B connected with the same conductor are 

 always charged at once, and that discharge may take place to either of the balls con- 

 nected with the discharging train, the intervals of discharge n and o may be properly 

 compared to each other, as respects the influence of large and small balls when 

 charged positively and negatively in air. 



1494. When the intervals n and o were each made = 0*9 of an inch, and the balls 

 A and B inductric positively, the discharge was all at n from the small ball of the 

 conductor to the large ball of the discharging train, and mostly by positive brush, 

 though once by a spark. When the balls A and B were made inductric negatively, 

 the discharge whs still from the same small ball, at n, by a constant negative brush. 



1495. I diminished the intervals n and o to 0*6 of an inch. When A and B were 

 inductric positively, all the discharge was at w as a positive brush : when A and B 

 were inductric negatively, still all the discharge was at n, as a negative brush. 



1496. The facility of discharge at the positive and negative small balls, there- 

 fore, did not appear to be very different. If a difference had existed, there were 

 always two small balls, one in each state, that the discharge might happen at that 

 most favourable to the effect. The only difference was, that one was in the induc- 

 tric, and the other in the inducteous state, but whichever happened for the time to 

 be in that state, whether positive or negative, had the advantage. 



1497- To counteract this interfering influence, I made the interval n = 0*79 and in- 

 terval = 058 of an inch. Then, when the balls A and B were inductric positive, the 

 discharge was about equal at the two intervals. When, on the other hand, the balls 

 A and B were inductric negative, there was discharge, still at both, but most at n, 

 as if the small ball negative could discharge a little easier than the same ball positive. 



1498. The small balls and terminations used in these and similar experiments may 

 very correctly be compared, in their action, to the same balls and ends when elec- 

 trified in free air at a much greater distance from conductors, than they were in those 

 cases from each other. In the first place, the discharge, even when as a spark, is, 

 according to my view, determined, and, so to speak, begins at a spot on the surface 

 of the small ball (1374.), occurring when the intensity there has risen up to a certain 

 maximum limiting degree (1370.) ; this determination of discharge at a particular 

 spot first, being easily traced from the spark into the brush, by increasing the di- 

 stance, so as, at last, even to render evident the time which is necessary (143G. 1438.). 

 In the next place, the large balls which I have used might be replaced by larger balls 

 at a still greater distance, and so, by successive degrees, may be considered as passing 

 into the sides of the rooms ; these being under general circumstances the inducteous 

 bodies, whilst the small ball rendered either positive or negative is the inductric body. 



1499. But, as has long been recognised, the small ball is only a blunt end, and, 

 electrically speaking, a point only a small ball ; so that when a point or blunt end is 



