26 



NA TURE 



[May 8, 1884 



men would .11 least have done their duty in urging its 

 claims and pointing oul whereby il might be protected 

 and augmi nted. H unfortunatel) happens thai up to the 

 pre .rut i mil- 1 1 ientifii men hat e brought no definite 

 3 , heme 01 proposition of this kind direi tl\ before Govern 

 ment ; ami the onus of neglect ma) consequently in a 

 r , inn ., ii le In .ml to rest now .n then door. 



The honour of renw ing tin-, responsibility lies directly 

 within the siopc of the newly-formed Society for Bio- 

 logii il I n\ estigation ; foi naturall) no othei bod) oi mi n 



could readil) put them ;el\ e i into i ommunii ation 



with the various kindred ocieties throughout the kingdom, 

 in. I thus obtain a unison of views upon this important 

 subject. I l" in i tep would be to elect an influential 

 repn entative deputation from the Society to wan upon 

 the Prime Minister for the purpose of urging the appoint 



mentofa Parlii ntarj I ommission to inquire exhaust- 



ivelj into the vai : subji i I - pert: g to a Zoological 



1 1 1 1 1 \ i j 



THL El 1 1 'TRh 'AL CONGRESS OF PARIS, 18S4 



Til E fii 1 ' ongre ■ ■ oi 1881 has 1 : good fruit. It 

 has not only brought about an approchement between 

 i i, ■ in, ians of all countries, but it has led to the adoption 

 ,,i ,in international system oi mea urement which will be 

 in universal use. It is satisfai tor) to find that thi re are 



qui i i whii h i an be amii abl) settled intern; all) 



II,, i ongri is was divided into three Commissions which 

 d ea ll H uii i i elei trii a! units, i z) atmospheric elei trii it) 

 and earth-currents, ; standard of light. The first Commis 

 s i,, n virtuall) dealt with the length of a column of mercur) 

 f on e square millimetre section which represented the 



ohm a iu\ ing been dei ided at the i iong t [881 that 



this should be the unit ol re listani e. Man) ph) ;ii i it i 

 l, ,,i been working on this in different i ountries and on 

 different method :, VI Via n art grouped the n 

 the follow ing u i ful table : 



I ,,„ 



B.A. 



British \ .... iation 

 1 Rayleigh Schuster 

 i Rayleigh (1882) 



II. \\-l» 



Webei (I.) 





Kohlrausch 



' \\ iedemann 



' Mascar I 



I w , bi 1 



J 



'i 



R6iti 



I',. Webei 



I orer (first) ... 







I Lenz 



1 (seci >nd 1 



Dorn 



I Ii. Weber ... . 



) Wild 



( Bailie 



8. Heat Joule 



From this it appears that the figures obtained by the 

 different methods were — 



B.A io6 - 2i 



Weber's 1 mi. a | 



Kirchhoff's 1 



Lorenz io6"I9 



A b r's 11 105-47 



I mile 106-22 



1 01 



Webei (II.) 



Column of 

 Mi n 1,1 j i" 

 Centitnecres 

 104-83 

 ioO'oo 

 loiej- 

 lo6'i6 

 I.S'Sl 



106-19 

 106-33 

 105-02 



106-29 



106-33 



105-9 



105-33 



107-1 



n 1"' ' I 

 106-13 

 I06-I9 

 105-46 

 I05-26 

 . I05-68 

 • "05-37 

 Io6'22 



The mean of which was 106-02, but 106 was taken as a 

 round figure sufficiently near the truth for all practical 

 and useful purposes. Heme the Congress decided that 

 "the legal ohm should be the resistance of a column oi 

 men iiiv of one square millimetre section and of 106 cm. 

 of length .it the temperature of freezing," and a resolu- 

 tion was passed desiring the French Government to 

 transmit this resolution to the different Go\ ei nments, with 

 a \ iew of making its adoption international. It was de- 



I ided that primary standards should be constructed in 



men tiry, but that si idar) coils I mm id be made of solid 



alloys, which should be frequently compared among them- 

 selves and with the prim. in standard. 



It was resolved that the ampere should be exactly 

 io _1 C.G.S. electromagnetii tinit oi current, and that the 



volt should be the elei 1 otivi force which maintained an 



ampere in a conductor whose resistance was the new ohm. 



We can now congratulate ourselves upon having a 

 scientific system of electrical units independent of any 

 particular instruments or of any particular process. It 

 is not absolutely exact. That is, the new ohm is not 

 [0° C.G.S. units, but it is the nearest approach to it that 

 1 .in be practical^ attained. It will probably be known 

 as the Congress ohm, to distinguish il from the true ohm 

 to" I ,G S.) or the B. V ohm oi 1S64. 



One subject ol regret is that Prof. Rowland's measure- 

 ments in Baltimore are not completed, and will probably 

 n.. 1 be read) before the i.m\ of the year. The United 



States Congress voted a large su 1 tie) to enable 



this to be done. 1 le is using a Plante - 11 . ondar) batter) 

 .on I emplo) ing three methods, -\ iz. Km hhoff's, Joule's, and 

 Lorenz's. His well-known experimental skill has given 

 much interest to this investigation of Rowland's. 



The second Commission dealt with atmospheric elec- 



tricit) ami earth-currents, and recommended that it was 



i.l, to send each yeai to the Bureau International 



des Administrations ["eMegraphiques in Berne the reports 



that we llected in the different countries, so that they 



might be distributed to the different 1 iovernments. 



The third Commission dealt with the standard of light, 

 and it was decided, not without considerable opposition, 

 1h.1t the mi. 1 for each simple light should be the quantity 

 of light of the same kind emitted in a normal direction 

 by a square centimetre ol lurface ol fused platinum at 

 the temperature oi solidifii at ion, and that the practical 

 unit of white light should be the total quantity of light 

 emitted normall) b) the same souri e. ttiis is a ver) 

 unsatisfactory standard. It was accepted be'eause there 

 was virtuall) none othei before. But it was obtained b) 

 ,,. k ,,,.. ob iervei VI. \ iolle ; il is not portal. le ; it is 



not 1 - produi ibli except at gri at expensi . and it is 



so eminently impracticableili.it n is scarcel) likely to be 

 generall) adopted. It is to be regretted that the British 

 Association Committee on a Stand. ml of White Light 

 has not yet finished its work, but we ma) hope that at 

 Montreal Capt. Abne) will In- able to give some results 

 which will give us a better and more pen til al standard. 



There was a universal consensus of opinion that the 



1. had faithfull) and earnestly done its work, 



that the success of its labours and the rapidit) of its 

 action was due to the energy and ability of M Cochery, 

 the Minister of Posts and Telegraphs. Our English 

 representatives were Sir William Thomson, Capt. Abncy, 



