CHAPTER V. 



The observational data. 



17. The observational data used for the investigation are the proper motions 

 of all stars brighter than the sixt magnitude, as given in Boss' Preliminary General 

 Catalogue, in all 4041 stars. As this catalogue is complete as far down as to the 

 magnitude 6.0 our material consists with a few exclusions of all stars in the heavens 

 brigter than this magnitude. 



In his above cited work Studies in stellar statistics II: The motion of the stars 

 Charlier has divided this material in 48 groups as to the position of the stars, 

 and for each region put together the motions in correlation tables. The 48 regions 

 are obtained by dividing the sky into »Squares» symmetrically distributed with 

 regard to the equator. The squares have equal area, and are selected according to 

 the following table. 



Squares of the northern hemisphere. 



Square 



Declination 

 between 



Right- 

 ascension 

 between 



Square 



Declination 

 between 



Right- 

 ascension 

 between 



Square 



Declination 

 between 



Right- 

 ascension 

 between 



c, 



0°— 30° 



0°— 30° 





30°— 66.°44 



0°— 36° 





66.°44— 90° 



0°— 180° ' 



c 2 





30°— 60° 



Bt 





36°- 72° 



A 





180°-360° 



c, 





60°— 90° 



B å 





72° -108° 









Ci 





90°— 120° 







108°— 144 9 









c, 





120°— 150° 



B b 





144°— 180° 









c„ 





150°— 180° 



B e 





180°-216° 









c, 





180° -210° 



B i 





216°— 252° 









c* 





210°-240° 



B t 





252°— 288° 









c 9 





240°— 270° 







288° -324° 













270°— 300° 







324° -360° 









Gu 





300°-330 ü 















c» 





330°— 3fi0° 















For each square of the northern hemisphere there is one diametrically situated 

 on the the southern hemisphere. As the squares are to be regarded as plane, the 

 proper motions of the stars in such a pair are referred to the same axes of coor- 

 dinates. 



