66 
question have been made by Auwers, while researches also have 
been carried out at Leiden for the zone observed there. KÜsTNER, 
by placing gauze screens in front of the objective of the telescope, 
has eliminated the error in a very satisfactory manner. Moreover 
I had the privilege of discussing various difficulties with Prof. 
BAKHUYZEN himself, and of experiencing his continued interest in 
my work, for which | take this opportunity of thanking him very 
sincerely. 
2. Material used. 
With Kisrner’s Catalogue (Aequin 1900) the following zone- 
catalogues of the Astr. Ges. (Aequin 1875) were compared in R.A. 
and Decl. : 
1. Berlin A, Decl. + 15° to + 20°; 
2. Berlin B, , + 20° ,, + 25°; 
o. ‘ueipziev lq. =A |, aos 
4. Leiden, eet er dB Ml 
The positions of the latter were reduced from 1875 to 1900 by 
means of the mean of the precession-values given in the two 
catalogues (constants according to PETERS-STRUVE). KüsTNeR'’s catalogue 
(Ki) proved .to have the following numbers of stars in common 
with the zone-catalogues, with the epochs as given: 
Number of stars __Epochs Difference of epochs 
Be A 768 1870,5—1896,5 26,0 years 
Be B 812 1881,0—1897,0 VOD 
Lei | 711 1874,3—1 896,45 vR bs Ns 
Leiden 926 1873,8—1898,0 242 ies 
Catalogue Berlin Brecker (Be B) has only a small difference of 
epoch with KüsrNer, but its great accuracy compensates this to a 
great extent. 
3. Immediate results of the comparison. 
To the differences Aa and Ad Kii—A.G. found directly by the 
comparison various corrections had first to be applied, in order to 
make them suitable for further discussion. These corrections are the 
following: 
1. The reductions of the A. G. catalogues to the system of Auwers’s 
fundamental Catalogue of the A. G. These were assumed according 
1) The comparison with Leiden in R.A. had been made before at the Leiden 
Observatory; I was able to use the results. 
