182 G. H. KNIBBS. 



stellar system. 1 He recognised the necessity of guarding against 

 any preponderating influence of stars in particular parts of the 

 heavens forming groups subject to a common drift, such as had 

 been suspected by Micheil, 2 and definitely revealed by the investi- 

 gations of Proctor, 3 Huggins, 4 Safford, 5 and others. This undue 

 influence can be avoided by grouping the stars in different regions, 

 and using the mean proper motion of the region. At the date 

 when the investigation was undertaken the positions and proper 

 motions of 622 stars of the two catalogues of the Astronomische 

 Gesellschaft were available. The general result of previous work 



was stated to be 



R.A. = 266-7, D.= +31-°0. 



Forming 20 groups arranged in order of their proper motions, it 

 was found that the distance from the adopted pole could be con- 

 nected with the proper motion itself by the equation 



— 0-°49 + 2-°183 — L _ 0-°005 ] 



P.M. (P.M.) 2 



— P.M. denoting the proper motion. Dividing the stars into six 

 classes according to the following scheme, the various results for 

 the place of the parallactic pole shewn in the following table were 

 obtained : — 



Mean 

 R.A.266-°l,D.+>°35 



These results were to be regarded as provisional merely. The 

 epoch for the determination of the proper motions was 1755 - 



1 Ueber die Bewegungen im Fixsternsysteine. — Astr. Nach., Bd. cxxv., 

 pp. 65 - 72. 



2 See Phil. Trans., 1783, pp. 276-277. 



3 Proc. Eoy. Soc. Lond.. Vol. xvm., pp. 169 - 171, 1869. 



4 Brit. Assoc. Eeports, Sect. 1873, pp. 34-35, and Proc. Eoy. Soc. Lond. 

 Vol. xxii., pp. 251 - 254. 



5 Monthly Not. Eoy. Astr. Soc, Vol. xxxviii., pp. 295 - 297, 1878. 



Class 



P.M. 



Weight. 



R.A. 



D. 



I. 



> 



•547 



> 1 



259°-4 



-0-5^ 



II. 



•292 to -547 



£tol 



270-3 



+ 26 



III. 



•198 



•292 



i t 



266-9 



- 1 • 3 1 



IV. 



•150 



•198 



i i 



4 3 



262-9 



+ 4-l( 



V. 



•120 



•150 



* i 



267-7 



-0-51 



VI. 



•100 



•120 



l l 



6 o 



269-3 



+ 2-2/ 



