( 609 ) 



dielectric (lisplaccincjit t» in (he aetliei', llic cnrieiit 1 .iiid the intvgiielic 

 force () are as JbHows ^) : 



die b rr: o , 



ft + ''"' ^- '^ "^ '^• 



die r^ = , 



rot f) r= 4 .T 1 = 4 .T (b + (.> ^') • 



4 .T ('^ rot b = — () , 



wliere c is the veh)city of Hiiht in tlie aether. Tu these eciuatiuns we 



iimst add the ioniuda 



f=:4rT.-'^b + [0.1)1 



for the electric force, i.e. the force, reckoned per unit cliar<!;e, wliicli 

 tiie aether exerts oji a chai',i2,ed element of volume. 



The ecinations take a somewhat more re,ii,idar loi-m if we ex|)i-ess 

 Q, b, ( and f in electrostatic units (preservinii' the elect i-onia,iiJietic nnil 

 for h) and a fnrther sim])lification is olttainetl, if, instead ofthennits 

 for charue an<l maunetic pole that are nsuallv taken as the basis of 

 the electi'ostalic and elect romaiiiielic systems, we choose iiew ones, 

 i/4.-T times smaller-). Ijilrodiicin,^- holli modilications, we have to 



o b I . , 



replace c>, b, 1 l»v -/^- , . /i— , . -;-^ , f l»v cy/i.^.t, hecanse this 

 ^ ' t'K4.Tr <'K4nr (•1/4.T 



letter mnsi now represent the force aclinn' on the new unit of charge, 



and likewise b by k 4.-T . (>. 



This leads to the equations 



'(!'- t» = (? , (I) 



-^ + die (o Ü) = , . . . . • . . (II) 



I == b -f o l> (Ill) 



div l) = (IV) 



rot f) =:r — I := — (b + () V) , (V) 



C 



1) See my Versuch ciner Theorie der eledrischen and optischen Erscheimnigen 

 ill heiüi'(ji('ii Körpcrn. I shall again suppose that all quantities are continuous 

 iunclions of llio (.•ooidiiialcs, so that e.g. Ilie density o will he regarded as passing 

 giadually to the value 0, which il lias outside an elerlroii. With the exception of the 

 letters, the notations aie the same as in the just uieiilioned Irealise. 'fhe scalar 

 product ot two vectors a and b will he denot(;il hy (n.li), the vectof product l>y 

 [ii.b]. The axes of coordinates are snppos('(| Jo I'euiaiu at rest, relatively to 

 the aether. 



") This clian^r has heen waiinly a(lvoc;ile(l by Hk.wisiuk. The units I shall 

 now usr :ne lljosr lli.U liave heen adojdrd foi' the .UatheinciiitfcltC Ijiciiclopadie. 



41* 



