278 INTRA-ATOMIC ENERGY. 



remarks, it acts upon iron at a distance with a force that may amount 

 to 110 kilograms per s(|uare centimeter. " How is it," nays the great 

 ph3^sicist, ''that these tremendous forces are developed within the 

 ether and that nevertheless solid bodies are free to move through 

 this solid { ■' We do not know and we can not tell whether we shall 

 ever know. We do not know the actual relations existing between 

 electricit}' and the ether, although it seems more and more evident 

 that one is derived from the other. 



Maxwell considers the ether ^ as composed of small s])heres animated 

 with a ver}' rapid movement of rotation Avhich they transmit from 

 one to another." Fresnel regarded its elasticity as constant, but its 

 density as variable. Other phj'sicists believe, on the contrary, that its 

 density is constant and its clasticit}^ variable. Most of them think 

 that it is not displaced l)y the movements of the material systems that 

 traverse it, but passes through the interstices (jf all molecules as water 

 passes through sand. 



The physicists are, howcAcr, wholly agreed that the ether is a 

 substance entirely different from matter and that it is not subject to 

 the hiAvs of gravitation. It is a sul)stance without weight and inuna- 

 terial in the usual sense of that word. It forms the world of the 

 impondera])l('. 



If the ether has no weight it must nevertheless have mass, since it 

 presents resistance to movement. This mass is very slight, since the 

 rapidity of the propagation of light is very great. If it were nothing 

 at all. such propagation would be instantaneous. 



The question of the imponderability of ether, which was dis(;ussed 

 for a long time, seems now definitely settled. It was quite recently 

 taken up by Lord Kelvin," and, for mathematical reasons, which I 

 can not detail here, he arrives at the conclusion that the ether is formed 

 ])y a substance in no wav under the control of the laws of gravitation — 

 that is to say, imponderal)le. '' But," adds he, " we have no reason to 

 consider it as aljsolutel v incompressil)le, and we may admit that a suf- 

 ficient pressure might condense it.""' 



It is prol)aV>le that from this condensation, effected at the begin- 

 ning of time l)y a mechanism of which we are entirely ignorant, are 

 derived the atoms which are considered b}" many physicists, notably 

 Larmor, as nuclei of condensation in the ether having the form of 

 little vortices endowed with an enormous rotatory velocity. " The 

 material molecule,'' writes this physicist, ''is formed entirely by the 

 ether, and by nothing else." '' 



It is difficult to believe that with such properties the ether is homo- 

 geneous. If it had been so, the worlds coukl not have been formed. 



« On the clustering of gravitational matter in any part < >f the universe. (Philo- 

 sophical Magazine, Jan., 1902.) 



'' Ether and Matter. 8vo. 400 pages. London, UtOO. Tlie work treats, however, 

 of ether and matter froni a mathematical i)oint of view only. 



