272 Mr. A. Tribe on the Distribution of 
It is evident from these results that as the plane of the plate 
became perpendicular to the direction of the lines of force — 
first, the area of — electrification increased on the + side (at 
least to 67^°) and decreased on the — side of the same plate; 
secondly, the area of + electrification decreased on the + side, 
and varied irregularly on the — side; and, thirdly, the area 
of the intermedial space generally increased on both sides. 
I have not explored the distribution of electricity on these 
plates by actual chemical analysis; but, judging from the 
colour and general appearance of the electro-deposits, it 
would appear that as the direction of the force approached a 
perpendicular to the plane of the analyzers the quantity of 
electricity on the plates diminished, and that the electric 
density also diminished at the respective ends of the plates. 
In support of the first of these conclusions, I would point 
to some experiments bearing on the subject described in my 
paper in the ' Proceedings of the Royal Society,' 1876, p. 313. 
III. When the direction of the lines of force is perpendicular 
to the plane of the metallic conductor. 
There evidently exists, as we have just seen, a relation 
between the quantity of electricity set up on an analyzing 
plate and the direction of the lines of force to its plane, from 
which it would follow that the minimum quantity would be 
found when the plane was perpendicular to the direction of 
the force. Such is the case. In fact, the only sign of electri- 
fication noticeable on a plate in this position, of the dimensions 
of those employed in the experiments described in II., was a 
mere trace of copper, longitudinally arranged along the central 
part of that side of the plate facing the + electrode. This 
latter fact was pointed out in my paper in the ' Philosophical 
Magazine' for June 1881, [5] xi. p. 448. 
The further investigation of this subject has brought out 
many points of interest. It has shown that the distribution 
of electricity on a metallic plate is totally different when its 
plane is respectively parallel or perpendicular to the direction 
of the lines of force. It has already been pointed out that, 
when the direction is parallel, the maximum electric density 
is at the ends of a rectangular plate, and diminishes towards 
the centre; but, conversely, when the direction is perpendi- 
cular, the maximum electric density would appear to be on the 
central parts and evidently diminishes towards the edges, 
where, and for some distance from which, signs of electrifi- 
cation are entirely absent. Again, when the direction is 
parallel, the points or angular projections of the conductor, 
as has also been pointed out, accumulate a proportionally very 
