192 



COMPARISON OF CATALOGUES OF STARS. 



1869 [Vierteljahrsschrift der astronomischen Gesellschaft, 1869, pp. 324-349]. This 

 catalogue consists of 336 principal stars, whose positions were at that time known 

 within narrow limits, and of 203 secondary stars whose places were known with less 

 precision. These two catalogues, however, form a nearly homogeneous system. 



The catalogue for 1ST"', published in Vol. XII. of the Annals was constructed 

 from the catalogue in Vol. X., combined witli two series of observations made during 

 the years 1*74 and 1875. It is to be noted, however, that these two catalogues 

 are not strictly comparable. The Pulkowa observations of the " Zusatzsterne " were 

 published by Professor Struve in 1*74 [Vol. IX.. pp. 83-88, "Vierteljahrsschrift 

 der astronomischen Gesellschaft"]. Under the supposition that the corrections to the 

 provisional places given in this publication were to be employed in the reduction of 

 the zone observations, they were used in the reductions of the Harvard College obser- 

 vations for 1874 and 1875. But it will appear from the table given below that the 

 systematic deviation of the Pulkowa observations from the final positions of the same 

 stars given in Publication XIV. of the Gessellschaft, are quite large, especially in 

 declination. In so far. therefore, as these stars were used in the determination of 

 the instrumental constants for the years 1874 and 1875, there is a departure from 

 the system upon which the catalogue for 1872 is based. 



Designating the entire provisional catalogue by P and the stars of this catalogue 

 which were used in the reduction of the Harvard College Observations by P' we have 

 the following relations between Auwers, Struve P and P' . In the comparison with 

 P 1 all the stars of the list are included, but in the comparison with P. 18 stars in 

 right ascension and 8 stars in declination were omitted on account of the magnitude 

 of the residuals : — 



The corrections given above may be assumed to be true for the mean declination 

 of the group to which they belong, and for twelve hours of right asceusion. It is 



