260 



SCIENCE. 



[N. S. Vol. XX. No. 504. 



occupy in any representation of ultimate 

 physical reality. 



Electricity was no more to the natural 

 philosophers in the year 1700 than the 

 hidden cause of an insignificant phenom- 

 enon.* It was known, and had long been 

 known, that such things as amber and glass 

 could be made to attract light objects 

 brought into their neighborhood ; yet it was 

 about fifty years before the effects of elec- 

 tricity were perceived in the thunderstorm. 

 It was about 100 years before it was de- 

 tected in the form of a current. It was 

 about 120 years before it was connected 

 with magnetism; about 170 years before it 

 was connected with light and ethereal ra- 

 diation. 



But to-day there are those who regard 

 gross matter, the matter of everyday ex- 

 perience, as the mere appearance of which 

 electricity is the physical basis; who think 

 that the elementary atom of the chemist, 

 itself far beyond the limits of direct per- 

 ception, is but a connected system of mon- 

 ads or sub-atoms which are not electrified 

 matter, but are electricity itself ; that these 

 systems differ in the number of monads 

 which they contain, in their arrangement, 

 and in their motion relative to each other 

 and to the ether ; that on these differences, 

 and on these differences alone, depend the 

 various qualities of what have hitherto 

 been regarded as indivisible and elementary 

 atoms; and that while in most eases these 

 atomic systems may maintain their equilib- 

 rium for periods which, compared with 

 such astronomical processes as the cooling 

 of a sun, may seem almost eternal, they are 

 not less obedient to the law of change than 

 the everlasting heavens themselves. 



But if gross matter be a grouping of 

 atoms, and if atoms be systems of electrical 

 monads, what are these electrical monads? 



* The modern history of electricity begins with 

 Gilbert but I have throughout confined my obser- 

 vations to the post-Newtonian period. 



It may be that, as Professor Larmor has 

 suggested, they are but a modification of 

 the universal ether, a modification roughly 

 comparable to a knot in a medium which 

 is inextensible, incomprehensible and con- 

 tinuous. But whether this final unification 

 be accepted or not, it is certain that these 

 monads can not be considered apart from 

 the ether. It is not on their interaction 

 with the ether that their qualities depend; 

 and without the ether an electric theory of 

 matter is impossible. 



Surely we have here a very extraordin- 

 ary revolution. Two centuries ago elec- 

 tricity seemed but a scientific toy. It is 

 now thought by many to constitute the 

 reality of which matter is but the sensible 

 expression. It is but a century ago that 

 the title of an ether to a place among the 

 constituents of the universe was authen- 

 tically established. It seems possible now 

 that it may be the stuff out of which that 

 universe is wholly built. Nor are the col- 

 lateral inferences associated with this view 

 of the physical world less surprising. It 

 used, for example, to be thought that mass 

 was an original property of matter, neither 

 capable of explanation nor requiring it; in 

 its nature essentially unchangeable, suffer- 

 ing neither augmentation nor diminution 

 under the stress of any forces to which it 

 could be subjected ; imalterably attached to, 

 or identified with, each material fragment, 

 howsoever much that fragment might vary 

 in its appearance, its bulk, its chemical or 

 its physical condition. 



But if the new theories be accepted these 

 views must be revised. Mass is not only 

 explicable, it is actually explained. So far 

 from being an attribute of matter consid- 

 ered in itself, it is due, as I have said, to 

 the relation between the electrical monads 

 of which matter is composed and the ether 

 in which they are bathed. So far from 

 being unchangeable, it changes, when mov- 



