260 THE ATOMIC THEORY. 



need not inquire whether the corpuscles are divisible or indivisible, 

 althougli for otliei" lines of investigation this question may be perti- 

 nent. But, no matter how far we may push our analysis, we must 

 always see that something still lies beyond us and realize that nature 

 has no assig-nable boundaries. That which philosophers call "the 

 absolute" or "the unconditioned" is forever out of our reach. 



Through many theories men have sought to g-et back a little farther. 

 Among these Lord Kelvin's theory of vortex atoms is perhaps the 

 most conspicuous and certainly the best known. It presupposes an 

 ideal perfect fluid, continuous, homogeneous, and incompressible; 

 portions of this in rotation form the vortex ring's, which, when once 

 set in motion by some creative power, move on indestructil)ly forever. 

 These rings may be single or linked or knotted together, and they 

 arc the material atoms. The assumed permanence of the atom is thus 

 accounted for and given at least a mathematical validity, ])ut we have 

 alread\" seen that the chemical units may not 1)c ((uite so simple. The 

 idtimate corpuscles, to use J. J. Thomson's words, ma}' be vortex 

 rings; the chemical atom is much more complex. On this theory 

 chemical union lias been explained by supposing that vortices are 

 assembled in rotation a])out one another, forming groups which are 

 permanent under certain conditions and j^et are capable of being 

 l)roken down. The vortex ring is eternal; its groupings are transi- 

 tory. This is a plausible and fascinating theory; if only we can 

 imagine the ideal perfect fluid and apply to it the laws of motion; 

 that done, all else follows. Unfortunatel}', however, the fundamental 

 conception is difficult to grasp and still more difficult to apply. So 

 far it has done little or nothing for chemistry; it has brought forth 

 no discoveries nor stimulated chemical research; we can only say that 

 it does not seem to be imcompatible with what we think we know. In 

 a certain way it unifles the two opposing conceptions of atomism and 

 plenism, and this may be, after all, its chief merit. 



But there are later theories than that of Kelvin, and some of them 

 are most daring. For instance, Professor Larmor regards electricity 

 as atomic in its nature, and supposes that there are two kinds of 

 atoms — positive and negative electrons. These electrons are regarded 

 as centers of strain in the ether, and matter is thought to consist of 

 clusters of electrons in orbital motion round one another. Still more 

 recentl}" Prof. Osborne Reynolds, in his Rede lecture," has oft'ered us 

 an even more startling solution of our problem. He replaces the con- 

 ventional ether by a granular medium, generally homogeneous, closely 

 packed, and having a density ten thousand times that of water. Here 

 and there the medium is strained, producing what Reynolds calls 

 "singular surfaces of misflt" between the normally piled grains and 



«0n an Inversion of Ideas as to the Structure of the Universe. C'ambridge, 1903. 

 The Rede lecture, delivered June 10, 1902. 



