DEPARTMENT OF MERIDIAN ASTROMETRY. 



205 



Several requests for proper-motions have been received and they 

 have been furnished when possible. As the reduction of the Albany 

 observations has not sufficiently progressed to allow of their use 

 without an undue amount of labor, with a great sacrifice in accuracj^, 

 proper-motions can be furnished only where recently published cata- 

 logues have contributed a sufficient amount of material to render the 

 proper-motion determinate. Such proper-motions will be greatly 

 strengthened when our observations are in condition for use. 



SELECTION OF STANDARD COMPARISON STARS. 



The selection of standard comparison stars for photographic plates 

 of large area is essentially complete from pole to pole for the first 9 

 hours of right-ascension. In making up this fist of stars the following 

 desiderata have been kept in mind: (1) Uniform distribution, ap- 

 proximating one star per square degree; (2) uniform magnitude, as 

 closely as possible within the limits 8.0 to 9.0 Adsual magnitudes; 

 (3) well-determined positions; and (4) a fair representation of the gen- 

 eral distribution of the stars in spectral tji^e. 



The Harvard magnitudes and spectral classifications have been 

 used, over 40,000 of the stars listed in the first three volumes of the 

 Revised Draper Catalogue being charted to form the basis of selection. 

 In order to secure those stars whose positions and proper-motions 

 are most determinate, preference was given to the stars to be contained 

 in the Second General Catalogue, the Intermediary Standard Stars of 

 the Astrographic Survey, and Gill's Zodiacal List. For those regions 

 where these catalogues did not furnish stars, a selection was made based 

 upon the data in the Yale Index of Stellar Positions. 



The total number of stars listed for the first 9 hours of right- 

 ascension is 15,442, 87 per cent of which (as shown in table 1) he between 

 the hmits 8.0 and 9.0 \'isual magnitude and 94 per cent between 7.8 

 and 9.2, a range of only 1.5 magnitudes. 



Table 1. — Distribution in magnitvde. 



