69 
allowable proper motion during the interval between the epochs. 
In this the two coordinates have had no influence upon each 
other; a star which had to be omitted in the computation of the 
E-mean of the Aa on account of too large a value was not exclu- 
ded from the Ad on that account. In this way in forming the 
E groups for each catalogue about 100 stars were excluded. 
As in the discussion of the results from the comparison between 
Kü. and Be A a great difference became apparent between the 
values of the precession-constant m derived from the bright and 
from the faint groups (that is from BA and BE on the one hand 
and from FA and FE on the other) it was thought desirable to 
institute a further research into this point. For this purpose the 
fainter group in Berlin A was split into two, one between magni- 
tude 8.50 and 9.15, the other below 9.15. For both groups, called 
F, and F, solutions A and E were made. In the following table 
these groups are found as F,A, F,E, F,A and F,E. 
As already said, in the formation of the E groups the two coor- 
dinates had no influence upon each other. The opposite point of view 
might also be defended, while it may be said in favour of the method 
here followed, that it is illogical to exelude stars from one coordi- 
nate because of a large accidental error in the other. In any case 
it seemed desirable to see what would be the influence of the exclu- 
sion, also according to the other coordinate. This was done for the 
R.A. of Berlin A; for this catalogue E' groups were formed for 
which the same exclusion-limits were used as in the EK groups, but 
in which exclusion also took place on account of the other coordi- 
nate. The groups formed on this principle are called BE’ and FE’. 
In the following table I have collected the hourly means formed 
after the different principles; in this table 0" means the group from 
2330™. to 0°30, ete. while under „ the number of stars used is 
given. The unit is in the R.A. 0.01, in the Decl. 01. 
