( 447 ) 



of tlie ,ü-alvaiioiiie1crs on the rcadijiu' on the otiici- nun ho calcnhilod 

 with a snl'liciiMil (h^uroc of accui-acv froni Ihc (hnitMisioiis of ihc 

 gal\anoinoh'i', Ihrii- mnliiai dislancc, and the approximahMl know- 

 ledj^-c of ihe inlcnsilv of \\\r cnrivnl. lu'foi-c, afler and helwecn \\\v 

 (Hlfei-enl detei-ininalions lh(> Iwo uahanoiiKMcM-s \\ ci-o read al Ihe 

 same lime in oi'(h'i' lo ascerlaiji Iheii- course. The lime was (h'lcr- 

 mined with a chi-onometei-. A\hieh Helved 120 limes a miniile, excrx 

 day it was conipai'cd with an aslrononiical eloek of great aeeni-ac\ . 



77/r roltdiiiclcrs. 



The ealho(h's eonsislcd of [dalinnm, Iwo of lliem were enj)-slia|>e(K 

 Ihe Ihird was a eyhnder eiKhnu' in a hemisj)hei'e ; a siher rod sei'xed 

 as anode. In order lo inlei-ee|»l parlicles, w hieh nnuiil fall IVcnn Ihe 

 anode a S()\iiLi'7r liltcrin<i-"|»a|ier linger was placed round il, mannfacliired 

 by Scjii.KieHKH and Sciiri,!.. A 20" „ nenlral solnl ion of Ag' K( )., formed 

 the eleclrolyle. This \\as pai'lly obtained frinn Iv Mkiu'K, Dai'msladi, 

 [)arlly from Ihe firm .1. W. (iiLTAV. htrmei'ly 1'. .1. Kipp and Sons, 

 at Delft. 



Two \()ltamctcrs were placed in the ciiriiit in order lo ascertain 

 that no irreunlarities occnrretl iji lhc deposition of the sil\ei'. In 

 most cas(»s the wei.uht of Ihe deposit al the cathode aüi'eed lo within 

 0,1 ni.^r., once it amonnted to more than 0,"i \\\.\xv. The mean \alne 

 of- Ihe two weights was assnmed for the wei.iiht of the (le])Osile(l siher. 



The weiiihts nsed for the weiginn<>' had been corrected by teslinii- 

 them lo a standard kiloui-ani. 



Iji the same way all scales nsed for the measnremeiils hax'e been 

 compare<l with a standard meter. \\ hose tlixisions are a,uaiii compared 

 with a standard leii,ij,tli of 2 d.m. \n hose corrections were accura- 

 tely known. 



The distance from the scales to the bitilar ma,uiiet<mieler and the 

 ,ual\aii(nnelers \\ as measured with a wooden scale of I) meters. Marks 

 ^^el•e made al distances of I meter and brass scales di\ide<i into 

 m.m. could slide alonu' the ends; these scales ended in points of 

 ixory. For the uaKanomelers the distance from IIk' scale to the üiass 

 froiil was measured, for the bitilar iiiaLi'netomeler the distance lo Ihe 

 mirror. For each obs(M-\;ilioii these distances were measured and also 

 the distance of the silk libres of the inau'iietoineters. The dilfereiil 

 correclioiis for the iiicliiialioii of ihe mirror, ihe thickness of the 

 •i'lass front, llie dislance from Ihe froiil lo the mii'ror, etc. were 

 appli(.M| lo the distance. 



The hniglh of ihe scale of 3 meters pro\ed not to be perfectly 



