68 
1. a “bright” group, called group B. 
2. a “faint” group, called group F. 
were formed. 
Further the ever difficult question of the exclusion of stars 
had now to be weighed. Nrwcoms, in his deduction of the 
precessional constant from the BRADLEY stars, excluded all stars with 
proper motion above certain limits depending upon the magnitude 
and entirely ignored these. In this way he loses more than '/, of 
the whole number of stars. In the reduction of the material of this 
paper it did not seem advisable to confine oneself to this method. 
Besides the deduction of the results in NewcoMB's manner I made 
a second calculation practically without exclusion, that is, only some 
extremely large differences were excluded. The work was therefore 
done in two ways: 
1. all stars (with the exception of a few very large differences) 
are used; solution A; 
2. stars with P.M. above certain limits are excluded: solution /. 
There were, therefore, four solutions made: BA, BE, FA, FE. 
Excluded unconditionally were: (see |): 
in Be A all stars with Aa >0% or Ad >7'5; 
iW Be. 5; a ssd. „Ard Soe 
me ethaan er oo eS OE. Ard BE 
in Leidens re NED s,s heen 
These are altogether only about twenty in number. Moreover, 
in all four catalogues the double stars are unconditionally excluded, 
being respectively 18, 31, 15 and 37 in number. It is unnecessary 
to point out that this last exclusion is certainly justified. As regards 
the unconditional exclusion on account of too large differences it 
inay be further remarked that in this the two coordinates have 
also exercised an influence upon each other, as stars with too great 
a Au are also excluded in d, and vice versa. In this way the A 
groups were formed. 
For the E groups the following values are accepted as the greatest 
Limits for the E-groups. 
Catalogue ES eee 8thmagnitude/9thmagnitude 
| 
Be A 0520. 30 | 0315 272°) WSI2? 1510 175 
Be B 0:12) 4.5 | 0.40 125. (008 4:51 0:06 1.5 
Lei I 020. 3:0.) 0.150 5: 0 PO MZ 320 7) 040 3.0 
Leiden | 0.20 2.5 | 0.20 2.5 | 0.20 2.5 | 0.20 2.5 
