i.tf 



NATURE 



[October 17. 1918 



h. Royal Institution, and are .1 store- 



ical si ii in e as il was then know n. In 



1 hi saj s : " I he dissemination ol the 



ii ii.iiui al philosophy and 1 hi misti \ be- 



1 ssi ntia] pari oi the design ol thi R03 al 



and this depai tmi nl must in the natural 



lt rangemenl be antei ioi to the applii alion 



,,f ii,, si ii nces to prai tii al uses I exi lude -ill 



knowledge but that which has already been applied to 



immediate utility would be 1 '1 ui faculties to a 



State ui si rvitude and to Frustrati the verj purposes 

 which we are labouring to accomplish. No discovery, 

 however remote in its nature from the subjects ol 

 daily observation, can with reason be declared wholh 

 inapplicable to the benefits ol mankind." 



The lectures covei the whole range of physics as 

 it was then known, and in thi last, the sixtieth, the 

 author concludes : " W hi 11 wi reflect on the state 

 of the sciences in general at the beginning ol the 

 seventeenth century and compare ii with the progress 

 which has been made since then in .-ill of them, we 

 shall be convinced that the last two hundred years 

 have done much more for the promotion of knowledge 

 than the two thousand which preceded them, and we 

 shall be -nil more encouraged bj the consideration 

 that perhaps the greater part of these acquisitions 

 have been male within fifty or sixty years only. 

 VVe have, therefore, the -satisfaction of viewing 

 the knowledge of Nature, not only in a state of 

 dvancement, but even advancing with increasing 

 rapiditv." 



Dr. Young lived one hundred years ago, and if then 

 these words were true, how much more true are they 

 to-day! The rate of growth of our knowledge of 

 inanimate Nature in the past twenty years or so has 

 tar surpassed anything lie evei contemplated, anil the 

 benefits that growth has brought mankind far exceed 

 all i,,. evei dreamed of. Not that the) are all benefits ; 

 the terrors el war, the sufferings of the innocent, the 

 poison-gas -hell, the bomb that kills women and 

 children, and tin- nameless honors Science has put it 

 into the power of human fiends to deal around forbid 

 h.it comforting dream. 



still, there is no doubt which waj the balance 

 turns. ' Contemplate modern life without physics 



ience ol 1 nerg) ; think of il with our knowledge 

 lectricity, what it w,as even when Young wrote, 

 with the steam-engine almost a toy, with ships de- 

 pendent still Upon the wind and tides, with the 

 engineer compelled to use human labour, assisted only 

 simpler mechanical devices, such as the inclined 

 some elementary arrangement of pulleys foi 

 his buildings and 1" idges. 



uides us in directing the national stores of 

 channels useful to man; it is it. this 

 mii owes his supremacy over the bruti 



create is to the discovery of those natural 



laws ivh i subject of study of the physicist 



that lie- | due. this statement of our subjei I 



U sufficient to indicate its extent. Clearly, to tieat 

 in turn of all ind indicate their connei Son 



with our national lite is : hopeless task for an hour's 



lecture. Then no! time to dial completely even 



with one, and mi 1 think sotw tppreciation of what 

 we owe to physical si iet lined il 1 attempt 



a very brief review oi our knowledge of electricity 

 one hundred years ago and of its progress since that 

 date. 



I h, age w as a ii i nl. o lish w as still 



inn, and had disi ovet ol the laws of 



statical electricity; he had shown how to combine 



n and hvdrogen to form water, and had used 



: . an- to produce nitrogen from the air. 



555, vol. 1 02] 



On the I ontinent Coulomb had verified experimentally 

 the inverse square law lor electricity by thi us. ..1 

 the torsion balance, and had investigated its distribu- 

 tion on conductors of various forms. Laplace ..nd 

 Poisson w . 1 1 active in applying mathematical • al- 

 culations to problems in electrostatics, and somewhat 

 I. ii. 1 (1828 'ge Green, the self-taught mathe- 

 matician In- was a Nottingham shoemaker who, after 



th. publicati f th.- paper referred to, entered at 



Cains College, 1 ambridge, became fourth Wrangler in 



1837, and di..l in [84] made h\ far the most im- 

 portant advanci up to that date in electrical theory. 

 The Leyden jat had long been invented, and some 

 experiments had been made on currents produced by 

 discharging .1 .lies oi condensers (Leyden jars) 

 through lone wins or obtained through statical elec- 

 trical machines; little was known of the properties n | 

 the current, beci ise no means of producing continuous 

 1 in rents • s isted 



Ihe science ol magnetism was in a similar ele- 

 mental condition. Gilbert, of Colchester, physician 

 to Queen Elizabeth, in his treatise "IV Magnete," 

 published in [600, had described the fundamental facts 



of th. subject, ..nd Coulomb had applied the torsion 



balance 1.. prove the inverse square law for magnetism; 



there was a vague idea that there must he some 

 connection between electricity and magnetism, hut of 

 electro-magnetism and all the vast possibilities it im- 

 plied I lure was no conception. With the new century 

 ...in a change, though even then progress, which 

 to Young, writing in 1808, seemed rapid, to us seems 



slow . 



In 1S00 Volta invented the voltaic pile, a pile of 

 discs of zinc ami copper, alternatelj separated by 

 flannel washer, moistened with dilute acid; a con- 

 siderable e.m.f., depending, of course, on the numbei 

 of coupl.s, is produced between the extreme discs, and 

 a small current can be drawn from the apparatus. 

 Then cam.' his "crown of cups," the primitive form 

 nf ham 1 plate of zinc and copper dipping' into 



a vessel (a cup) filled with dilute acid, and connected 

 h\ a wir. outside the vessel; a number of these ar- 

 ranged in series formed the crown. 



Twentv vears later (in 1820) came Oersted' 

 discovery, described in his " Experimenta ana effectum 

 conllictus eli.uui in arum magneticum," in which 

 he described for the first time the action of a curreql 

 on a magnet ; the ordinary method of measuring a 

 current l>\ the deflection of a magnet was a natural 

 result, and Schweigger invented the galvanometer, 

 while Ampere with wonderful rapiditv established ele- 

 mentary laws which regulate the action of one current 

 on another, and laid the foundation of electro- 

 dynamics. In the same year Arago, followed in 1821 

 by Sir Humphry Davy, discovered independently the 

 power of a .in 1 .nt to magnetise steel. \rago's further 

 discover) in [824 of the rotation of a magnet when 

 suspended freeh over a rotating copper disc led ulti- 

 mately to i, suits of the ven greatest importance, 

 which culminated in 1831 in Faraday's discovery of 

 the induction of electric currents and the elucidation 

 ..I theii law s. 



The child "was horn whose birth was soon 1.. I" of 

 such immense consequences to mankind, hut pioh.il.h 

 no one, not . vi 11 I-'arada\ himself, realised all that was 

 to follow 



In [827 Ohm stated the law now universally known 

 h\ his name, and its- statement led to much important 

 work with a i. w to iis complete verification. The 

 fundamental laws of electrolysis were enunciated by 

 I'.nad.n in iS ;; , .and for King there was an ardent 

 conlro\.is\ a- 10 Ihe source of the electromotive force 

 in a galvanic cell. 



