REPULSION RESULTING FROM RADIATION. 
527 
condensed as these vibrations diminish in amplitude, whilst heat drives them apart, 
expanding a solid, changing a solid into a liquid and a liquid into a gas. 
The masses used in my experiments are likewise repelled by heat and drawn together 
by cold. And it is with no weak force or feeble action that I have been dealing. It 
is so decided that in some of my balances the approach of a finger will completely 
overturn them, whilst the radiant warmth of the body affects them 6 feet off ; and at 
higher temperatures and with larger masses the action must be still more energetic. 
81. It is not unlikely that in the experiments here recorded may be found the key 
of some as yet unsolved problems in celestial mechanics. In the sun’s radiation passing 
through the quasi vacuum of space we have the radial repulsive force, possessing suc- 
cessive propagation, required to account for the changes of form in the lighter matter 
of comets and nebulae ; and we may learn by that action, which is rapid and apparently 
fitful, to find the cause in those rapid bursts which take place in the central body of 
our system ; but until we measure the force more exactly we shall be unable to say 
how much influence it may have in keeping the heavenly bodies at their respective 
distances. 
So far as repulsion is concerned, we may argue from small things to great, from pieces 
of pith up to heavenly bodies ; and we find that repulsion shown between a cold and 
warm body will equally prevail, when for melting ice is substituted the cold surface of 
our atmospheric sea in space, for a lump of pith a celestial sphere, and for an artificial 
vacuum a stellar void. 
Attraction being developed by radiant heat under influences connected with air, it is 
not easy to conceive how it will be produced for cosmical purposes by heat ; the upper 
surface of our atmosphere must present a very cold front, and from this we might argue 
repulsion by the sun, unless we fill space with a body acting like air, when we should 
have attraction. We might readily find conditions for both, but how to harmonize 
them is a difficulty. 
Although the force of which I have spoken is clearly not gravity solely as we know 
it, it is attraction developed from chemical activity, and connecting that greatest and 
most mysterious of all natural forces, action at a distance, with the more intelligible 
acts of matter. In the radiant molecular energy of solar masses may at last be found 
that “agent acting constantly according to certain laws” which Newton held to be the 
cause of gravity. 
