694 Proceedings of Royal Society of Edinburgh. [sess. 
16. Let us now see how repulsion between two negative bodies 
can be accounted for. In the space between the two bodies the 
ether would be less energised owing to their small radiation of 
electricity into this space ; it would become more densely packed, 
therefore, in this space, and motion or energy from the outside 
penetrating quickly into it, and energising the densely packed 
ether, sufficiently accounts for their separation. 
17. Next, let us enquire how “Attraction” is brought about 
between positive and negative bodies. In the space between, the 
ether would he under a state of dilatation by the strong action of 
the positive radiations on the feeble negative radiations, sweeping, 
or tending to sweep, them entirely out of the field into the back- 
ground. If this state of matters could go on unchecked, a near 
approach to a vacuum would he formed ; hut it cannot go on un- 
checked, for the greater the dilatation the greater the resistance to 
it by the densely packed ether in the background, therefore there 
would be a strong tendency for the bodies to rush together. 
18. We will deal next with the attraction between a positively 
electrified body and a neutral. The attraction between a positive 
and a neutral is brought about in precisely the same way as 
between a positive and a negative, only it is not so powerful, for 
the neutral may be looked upon, relatively to the positive, as a 
weak negative, i.e. its radiations are more powerful than those 
of a negative, therefore the action of those of the positive upon 
them is not so effective in driving them out of the field. 
If, though, the neutral is a good conductor, the attraction 
between them will approximate to that between positive and 
negative, for the side of the neutral next the positive becomes 
negative by induction, therefore there will he, and for the same 
reason, the same tendency to approach as between positive and 
negative, only, as said before, not so strong. If the neutral body 
were a had conductor, less motion would he pressed out of the side 
next the positive, i.e. it would become less negative, with the result 
that there would be less “ attraction.” 
19. And now to examine the action between a negatively 
electrified body and a neutral. This action is also the same in kind 
as that between a positive and a negative. We may regard the 
neutral, relatively to the negative, as a weak positive, and acting 
