( 822 ) 



A^, A^, A,., etc., formed l\v the centres of flie parlicles in tlie iiioviii"' 

 system 2£, is obtained from A\, A'.,, /!';,, etc. I)v means of a deformation 

 "ill 



- J 1 'i~ ]■ According to what lias l)een said in § 8, the centres 



Avill of themselves take these jtositions A\, A\, A\, etc. if originally, 

 before there was a translation, they occnpied the positions A^, A.^, A^, etc. 



We may conceive any point /"*' in the space of the system 2£' to 

 be de])laced Iw the above deformation, so that a definite ])oint Pot' 

 2£ corresponds to it. For two corresponding points /^' and 7^ we shall 

 define corresponding instants, the one belonging to /■*', the other to 

 P, by stating that the true time at the first instant is equal to the 

 local time, as determined by (5) for the point P, at the second instant. 

 By corresponding times for two corresponding particles we shall 

 understand times that may be said to correspond, if we fix our 

 attention on the centres A' and A of these particles. 



h. As regards the interior state of the atoms, we shall assume that 



the configuration of a particle .1 in ^ at a certain time may be 



/ 1 1 lA 

 derived l)y means of the deformation ly, — , —I from tlie conli- 



\ n't t ^ J 



guration of the corresponding particle in ^', such as it is at the 

 corresponding instant. In so far as this assumption relates to the form 

 of the electrons themselves, it is implied in the first hypothesis of § 8. 



Obviously, if we start from a state really existing in the system 

 ^' , we have now" completely defined a state of the moving system ^. 

 The question remains however, whether this state will likewise be 

 a possible one. 



In order to judge this, we may remark in the first place that 

 the electric moments which we have supposed to exist in the moving 

 system and which we shall denote by p, will be certain definite 

 functions of the coordinates .v, y, z of the centres A of the particles, 

 or, as Ave shall say, of the coordinates of the particles themselves, 

 and of the time t. The equations which express the relations between 

 p on one hand and .r, y, z, t on the other, may be replaced by other 

 equations, containing the vectors p' defined by (26) and the quantities 

 x\y',z',t' defined by (4) and (5). Now, by the above assumptions 

 a and J>, if in a particle A of the moving system, whose coordinates 

 are ,v, y, z, we find an electric moment p at the time t, or at the 

 local time t' , the vector p' given hy (26) will be the moment which 

 exists in the other system at the true time /' in a particle whose 

 coordinates are .i', //', z' . It appears in this way that the equations 

 between p', .r' , ?/', z' , t' are the same for both systems, the diffe- 

 rence being only this, that for the system -^"' ^vithout translation 



