1890-91.] THE LUMINIFEROUS ETHER. 93- 



THE LUMINIFEROUS ETHER. 



By J. M. Clark, M.A., LL.B. 



{Read igth January, i88g.) 



Before proceeding to point out some of the properties of the lumin- 

 iferous ether, I may be asked, How do we know that such a substance 

 exists .-' Is not the very existence of the ether a mere theory, and as such 

 a part of one of those systems of which Tennyson says, " They have 

 their day and cease to be.^" Eye hath not seen it, ear hath not heard it, 

 the hands of man have not handled it. The balances of the most skilful 

 physicist have not weighed it, nor has the most powerful reaction of 

 the chemist detected it. 



Yet not only are physicists certain of its existence, but Tyndall has 

 justly remarked (in his work on Molecular Physics) that its relations to 

 the matter of the universe must mainly occupy the investigations of future 

 scientists ; and in his recent lectures on Molecular Dynamics, Sir Wm. 

 Thomson said that we know the luminiferous ether better than we know 

 any other kind of matter in some particulars ; that we know more about 

 it than we do about air, water, glass or iron. 



In the first place we all know that the heat and light of the sun, 

 which are now conclusively established to be forms of energy, are trans- 

 ferred to the earth, and from the sun our main supplies of energy 

 undoubtedly come. 



Some recent writers seem to think that the demonstration of the impos- 

 sibility of what is called " action at a distance " has been the work of 

 recent years. But long ago Newton said (in one of his famous letters to 

 Bentley), " That one body may act upon another at a distance through a 

 vacuum without the mediation of anything else by and through which 

 their action may be conveyed from one to another is so great an absurdity 

 that no man who has in philosophical matters a competent faculty of 

 thinking can fall into it." 



We have seen that the sun acts on the earth through the transmission 

 of heat and light from the sun to the earth. 



From this one of two things follows, either (i) heat and light are 

 substances, forms of matter, which has been conclusively established to be 

 impossible, or (2) the heat and light being, as they indisputably are /<7;'/«x 

 of energy, must be transformed by the mediation oi somet/mtg. 



