STARS IN COMA BERENICES. 



363 



then will 



[/(/-7;)] = o, 



and equations (2) become 



[/]«o— [/^]=o 



whence at once 



VpBI 



Oq =-j; — ^ with the weight [/] 



X pB{t — rA-\ 

 Vo = — [-^(^_ 7-^)2] ^ith the weight [/(/- 7^)2]. 



If now we write 



Cn B = E, 



and remember that 



smce 



we get finally the formulae 





(3) 



(4) 



(5) 



The probable error of an observation B whose weight is unity 

 is, by the usual formula 



^ = ±•6745 





the v's being the residuals obtained by substituting the final 

 values of a.^ and An^ in equation (i). Hence the probable 

 error of 



2q at the epoch 7^==: — — — ^=rT 



Vlp] 



^N 



V[CD] '^ 



2o reduced to 1875 using ^^Q=VrT^+ 1 (1^75 — ^i) ^-^1^= ''1. 

 (23) 



(6) 



