326 



SCIENCE. 



[N. S. Vol. XII. No. 296. 



*here is, of course, mueh excuse for those 

 who were not specialists in this particular 

 line. But attention is called to it as illus- 

 trating the general trend of ideas at the 

 time when the writer first attempted to 

 introduce his theory. 



Some time later, in Europe, similar ideas 

 were put forward by other writers, notably 

 by Eichartz, Lorentz, Chattock, Larmor 

 and others, and at the present time the 

 theory may be considered to be on a strong 

 footing. 



The theory thus originated by me, that 

 the ionic charge is always associated with 

 the atom, in all conditions, naturally led to 

 the conception that it might be the inertia 

 effect of such a charge, acting in the way 

 first shown by J. J. Thomson, which caused 

 the inertia of matter. This idea was ad- 

 vanced by several writers, amongst others 

 by Dr. Kennelly. But it was easily shown , 

 and had in fact been ascertained previously 

 by the writer, and no doubt by others, that, 

 with the known dimensions of the atom, 

 this hypothesis was untenable, the effect so 

 produced being only about 10"" of that 

 necessary. 



In subsequent papers,* the writer put 

 forward the idea that " the atoms may be 

 formed of vortex rings arranged in different 

 kinds of space nets, with the direction of 

 rotation of the vortex rings such as will 

 make these combinations stable," and that 

 " one might picture to one's self a vast por- 

 tion of the ' atom dust ' from which Mr. 

 Spencer develops his universe, made of vor- 

 tices and splitting up in these 67 ways to 

 form the elements." 



This hypothesis had for some time no 

 real foundation. During the past year, 

 however, the wonderful work of J. J. 

 Thomson has resulted in almost certain 

 proof of the fact that the atom is really 

 made up of a large number of what he 



* Articles on Insulation, Elect. World, March, 1893 

 et Sfq- 



calls ' corpuscles,' each possessing an elec- 

 tric charge. In this paper (in the December 

 number of the Phil. Mag., 1899), Thomson 

 recurred to the question of inertia being an 

 electrical effect, but considered that there is 

 at present no evidence to decide whether 

 the corpuscles are small enough. 



In 1891 the writer had shown that the 

 atoms of a body in the solid state must be 

 nearly touching each other, and that the 

 phenomena which were supposed to militate 

 most strongly against this supposition could 

 be accounted for in a very simple manner. 

 In a later paper* (read beforethe A.A.A.S., 

 Columbus meeting, August, 1899), I showed 

 that though the atoms were nearly touch- 

 ing each other, yet they really filled less 

 than J per cent, of the space which they 

 occupied to the exclusion of other atoms. 



From the two facts, i. e., Thomson's dis- 

 covery that the number of corpuscles in a 

 hydrogen atom is of at least the order of 

 one thousand, and the writer's discovery 

 that the real volume of the atom is but a 

 small portion of the space occupied by the 

 atom, we arrive at the conclusion that the 

 atom must be made up of a large number 

 of corpuscles separated from each other by 

 distances considerably larger than their di- 

 ameters. This gives us data for making an 

 approximate estimate as to the ability of 

 the corpuscular charges to account for the 

 inertia of the atom, and on making this 

 calculation, we find, as the writer has 

 shown, f that it really is the probable cause. 



In other words, we may feel fairly con- 

 fident that inertia is really not a separate 

 and distinct thing, but merely a property 

 due to the fact that the atom is made up 

 of a very large number of electric charges. 



I have recently found that gravitation 

 can also be accounted for as a property 



* ' A Determination of the Nature of the Electric 

 and Magnetic Quantities and of the Density and 

 Elasticity of the Ether, ' Phys. Rev., January, 1900. 



t' Inertia.' Elect. World, IQQO. 



