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KNOWLEDGE & SCIENTIFIC NEWS. 



[Sept., 1904. 



to compare the different modes in which from time to time 

 this intellectual picture has been drawn could not fail to 

 suggest questions of the deepest interest. With those which 

 were purely philosophical the character of the occasion pre- 

 cluded him from dealing : with those that were purely scientific 

 his own incompetence forbade : but there were some questions 

 near enough the dividing line to induce one to consider them. 



He would take, therefore, for his point of departure the 

 closing years of the Eighteenth Century, a little more than 

 a hundred years after the publication of Newton's'- Principia.'' 

 If at that period the average man of science had been asked 

 to sketch his general conception of the physical universe he 

 would probably have said that it consisted essentially of 

 various sorts of ponderable matter, scattered in different com- 

 binations through space, exhibiting various aspects, but through 

 every metamorphosis obedient to the laws of motion ; always 

 keeping its mass unchanged, and exercising at all distances a 

 force of attraction on other material masses, according to a 

 simple law. The late Eighteenth Century physicist might 

 have added the so-called " imponderable " heat to the categorv 

 of ponderable matter, together with the two ■• electrical fluids." 

 and the corpuscular emanations supposed to constitute light. 

 In the universe as thus conceived '-action at a distance " was 

 the most important form of action, the principle of the con- 

 servation of energj' was undreamed of. clectricitv and mag- 

 netism played no great part in the whole of things, nor was a 

 diffused ether required to complete the machinery of the 

 universe. Within a few months of the date assigned to the 

 hypothetical physicist came an addition to this general 

 conception of the world designed profoundlv to modify it. 



A hundred years ago Voung opened, or re-opened, the great 

 contro%-ersy which finally established the undulatory theory of 

 light, and with it a belief in an interstellar medium of which 

 undulations could be conveyed. But this discoven,- was much 

 more than the substitution of a theory of light consistent with 

 the facts for one which was not. Here was the first introduc- 

 tion of a new and prodigious constituent — the ether — into the 

 scientific world picture. Unending space was no longer thinh- 

 strewn with suns and satellites. It was now filled with a con- 

 tinuous medium. It gave promise of strange developments. 

 It could not be supposed that the ether, if its reality were once 

 .admitted, existed onlv to convey through interstellar space the 

 vibrations of light — the vibrations which happened to stimulate 

 the optic nerve of man. Intended originally to fulfil that 

 function, to that it could never be confined. It conveyed light 

 and radiant heat and electrical waves and Hertzian waves 

 and waves to which the human perception makes no response. 

 But that was not all or nearly all. If we jumped the centurv 

 from 1S04 to 1904 and attempted to give in outline the 

 scientific world picture as it now presented itself to contem- 

 poran.- speculation, we should find not only that it bad 

 been greatly modified by new laws and new disco\eries, 

 but chiefly by the more and more important part which elec- 

 tricity and the ether occupied in any representation of ultimate 

 physical reality. Electricity in 1700 was no more to the 

 philosophers than the hidden cause of the insignificant pheno- 

 mena by which amber or glass, when rubbed, attracted small 

 objects brought into their neighbourhood. It was fifty years 

 before its effects were perceived in the thunderstorm ; a hundred 

 years before it was detected in the form of a current : one hundred 

 and twenty years before it was connected with magnetism ; one 

 hundred and seventy years before it was connected with light 

 and with " ethereal radiation." But to-day there were those, 

 the protagonists of the electric theory of matter, who regarded 

 gross matter as the mere appearance of which electricity was 

 the physical basis. Such theorists thought that the elementarv 

 atomwasitselfbutacollectionof monads or electrons, which are 

 not electrified matter but electricity itself — that those systems 

 differed in the number and arrangement and relation of their 

 electrons, and that on those differences depended the various 

 qualities of atoms. Finally, that, while in most cases those 

 atomic systems might maintain their equilibrium for periods 

 that seemed almost eternal, yet they were not less obedient to 

 the law of change than the everlasting heavens themselves. 



But if gross matter was a grouping of atoms, and atoms 

 were systems of electrical monads, what were these electrical 

 monads ? It might be that, as Dr. Larmor had suggested, 

 they were but a modification of the ether — a modification 

 roughly comparable to a twist or a knot in the ether. 

 Whether that were accepted or not. it was certain that these 



electrical monads could not be considered apart from the 

 ether. Their qualities depended on their interaction with it. 

 Without it an electric theon.- of matter was impossible. 

 Surely here was the most extraordinary of revolutions. Two 

 centuries ago electricity seemed but a scientific toy. It was now 

 thought by many to constitute the reality of which matter was 

 but the sensible expression. It seemed possible now that it 

 might be the stuff out of which that universe was wholly built. 



Nor were the collateral inferences less surprising. It used 

 to be thought that mass was an original property of matter ; 

 neither capable of explanation nor requiring it ; in its 

 nature essentially unchangeable ; sufl'ering neither augmenta- 

 tion nor diminution under the stress of any forces to which it 

 could be subjected ; unalterably attached to and identified 

 with each material fragment. But if the new theories \\ ere 

 accepted, those views must be revised. Mass was not only 

 explicable, but explained. So far from being an attribute of 

 matter, it was due to the relation between the electrical 

 monads of which matter was composed and the ether in which 

 thej- were bathed. So far from being unchangeable, it changed 

 when moving at very high speeds with every change in its 

 velocity. Perhaps, however, the most impressive alteration 

 in the cosmical picture was in its view of the distant suns and 

 their satellites — the stars visibly incandescent and in process 

 of transformation from the nebula whence they sprang to the 

 frozen darkness to which they were predestined. What of 

 the invisible multitude of heavenly bodies in which the process 

 had been completed ? According to the ordinary view they had 

 reached a state when all possibilities of internal movement were 

 exhausted. At the temperature of intersteUar space chemical 

 action and molecular action would be impossible; and the 

 stars and their constituent elements had no source of 

 replenishment of their exhausted energ\- except by some 

 celestial collision. But this view must be profoundly modified 

 if we accepted the electric theory of matter. We could no 

 longer hold that if the internal energy of a sun were as far as 

 possible converted into heat which could be radiated away, 

 then the sun"s whole energv- would be exhausted. On the 

 contrary, the amount thus lost would be absolutely insignifi- 

 cant compared with what remained stored up within the sepa- 

 rate atoms. The system in its corporate capacity would become 

 bankrupt. The wealth of its individual constituents would 

 remain undiminished. They would be side by side without 

 movement, without affinity, yet each, however inert in external 

 relations, the theatre of violent forces, by the side of which 

 those that shattered a world and revealed it as a flaming new 

 star to the astronomer's telescope were negligible. 



In common w ith all living things, we seemed to be practically 

 concerned with the feebler forces of Nature and with energy in 

 its least powerful manifestations. Chemical affinity and co- 

 hesion were, on this theory, no more than the slight residual 

 effects of the internal electrical forces which kept the atom in 

 being. Gra\itation. though it were the shaping force that 

 concentrated nebute into suns and satellites, was trifling com- 

 pared w ith the attractions and repulsions between electrically- 

 charged bodies : and those again sank into insignificance 

 beside the attractions and repulsions between the electrical 

 monads themselves. The irregular molecular movements 

 which constituted heat, on which the very possibility of organic 

 life seemed to hang, could not rival the prodigious energy- 

 stored within the molecules themselves. Vet this prodigious 

 mechanism seemed outside the range of our immediate inte- 

 rests. We li\ed merely on its fringe. It had no promise of 

 utilitarian value ; we could not harness it to our trains, ^"et 

 not less did it stir the imagination. Its marvels were greater 

 than those which in the starry- heavens had from time 

 immemorial moved the worship and wonder of mankind. 



The President went on to comment on the acute intellectual 

 gratification which the theorv- awakened, a satisfaction almost 

 cESthetic in its intensitj' and quality. It was, he said, a senti- 

 ment possibly derived from an instinct, not hghtly to be 

 ignored, in favour of the belief that the material world should 

 be a modification of a single medium rather than a composite 

 structure. These obscure intimations about the nature of 

 reality deserved, he thought, more attention than had yet been 

 given to them. That they existed was certain. The difficulty 

 that arose was when experience apparently said one thing and 

 scientific instinct persisted in saying another. That these new- 

 views of matter diverged violently from those suggested by 

 ordinary- observation was plain enough. No scientific educa- 



