16 BEYOND THE LIMITS OF VISION. 



which cannot be further decomposed, or reduced to anything 

 simpler, by any means known to them. Still there are few who 

 really believe that those simple elements are the last and lowest 

 condition of matter. The physicist who has not had his dream 

 or his theory of the unification of all matter, must be the one 

 who never thinks beyond the tables. I will endeavor to explain 

 to you that one which has occupied such minds as those of 

 Helmholtz, Maxwell and Sir William Thomson. 



It is now no longer questioned that all space is filled with a 

 highly elastic, all-pervading ether. Light and heat are simply 

 wave motions, and it is impossible that they should come to us 

 from the stars and the sun, except there were something to move, 

 some material medium all the way from those bodies to the earth. 

 Again, this medium retards light in coming from the sun to the 

 earth just eight and one half minutes. Now one of the defini- 

 tions of matter is, that which presents an obstacle to force. 

 Therefore the luminiferous ether, which does present an obstacle 

 to the passage of the light force, is material in its composition. 

 It is perfectly elastic, that is, its parts move among themselves 

 without friction, as is shown by the almost instantaneous passage 

 of the radiant forces through it (182,000 miles in a second). It 

 is beyond all conception minute in its structure, for it fills in 

 between the ordinary particles of matter, so that light, which uses 

 only this medium for its transmission, passes almost as readily 

 through air as through space, but is a little retarded in the more 

 solid material of glass and transparent crystals. Thus we have 

 furnished us a material substance pervading all space, of the 

 utmost tenuity and elasticity. Let us see if there is any way in 

 which atoms and molecules could be manufactured out of it. 



You have all probably seen a tobacco smoker make little rings 

 of smoke from his mouth, or a steam locomotive, when just 

 starting, puff up great black rings of smoke that ascend to consid- 

 erable distances unbroken. I wish I could show you the beautiful 

 illustration of this which Prof. Tait exhibits to his audiences. 

 He produces by chemicals a dense smoke in a box some eighteen 

 inches square, with a cloth stretched over one end, and a round 

 hole in the opposite side. Then some smart blows struck on the 



