( 429 ) 



III most npplications p wnulil he llio velnrity ol' tlie eurtli in its 

 yeaily motion. 



t; 4. Now, in Older to siniplil'y tlio oqniitions, the following 

 quantities mn\ he tiikeii ;is imleoendent vaiiiihlos 



. (1) 



Tlio last, of these is the time, reckoned from on instant that is 

 not the same for all points of space. i)nt depends on tlie place we 

 wish to consider. We may call il I he /oral Unit', to distinguish il 

 from the iinhrrsal time t. 



Tf we pnt 



T' _ 



we shall have 



A-/. L_/,3 J^ 1_ L-A 1-1 ^-1 



The expression 



3ülx 3 ia,/ 3 31. 

 3 X 3 y 3 «' 



will he denoted by 



Div' 31 . 



Wo shall also introduce, as now dependent variables instead of 

 the components of ö and ^, those of two other vectors %' and Sp , 

 which we define as follows 



5'^ = 4 n: F 2 b^, g',, = 4-Tk V~ b^ — k p^. .fx-, 5'. — 4::ikV~ t>- + J, p^ .p^, 

 jp'x = k .fix, .fp',/ = k" .^,j -\- in k^ px b:, -0'-- = /'•■- -0»= — 4 ;r ^■■- p^ by. 



In this way I find by transformation and mutual combination of 

 the equations (lb)— ^(Vi,) : 



