2g Astronomy 



observation in determination of proper-motions with a high degree of precision, 

 especially in the systematic sense. Results of researches leading up to the present 

 work have been published in Volume XXVIII of the Astronomical Journal. Therein 

 are described the steps by which the results of the various original catalogues of 

 observed star-positions are made systematically consistent one with another, and 

 with a resulting normal system. These and subsequent labors in preparation of the 

 present work have led to various useful results, additional to those concerning the 

 main issue computation of systematically accurate proper-motions. Thus, the 

 present work contains very carefully computed positions of all the stars suitable 

 to be classed as standard stars. The systematic errors of observation due to magni- 

 tude-equations of the respective observers have been eliminated from the right- 

 ascensions of the catalogue with substantial success. In the catalogue is incor- 

 porated a Normal Uranometry prepared by Dr. S. C. Chandler. This is founded 

 upon all the most important measurements and estimates of brightness, rendered 

 homogeneous by the application of systematic corrections for color and position 

 in the sky. Three appendices contain respectively : 



Appendix I. Ephemerides of Polar Stars. 



Appendix II. Notes to the Catalogue, Periodic Proper-Motion, etc. 



Appendix III. Systematic Corrections and Weights. 



No. 246. Albany Zone Catalogues for the Epoch /poo. Quarto, xxvni-f-249 pages. 

 Published 1918. Price $5.00. 



Boss, LEWIS. Catalogue of 8276 Stars between 20" and 41 of South Declination. 

 ROY, ARTHUR J. Catalogue of 2800 Stars between 2 of South and i c of North 

 Declination. 



The catalogues contain the results of observations made chiefly in the years 

 1896-1900. The observations of the first catalogue, which are strictly differential, 

 were designed to meet the need of star positions in a region of the sky difficult 

 of access to the principal European observatories. The second catalogue supple- 

 ments the observations taken at Nikolaief. A third part of the publication contains 

 the standard star positions observed in determining the system upon which the 

 zone observations of the first catalogue are based and a number of miscellaneous 

 star positions. Other miscellaneous stars form the fourth part. An appendix 

 contains a list of the proper-motions amounting to more than 10 seconds of arc 

 per century. 



No. 119. PERRINE, CHARLES D. Determination of the Solar Parallax from Photo- 

 graphs of Eros made with the Crossley Reflector of the Lick Observa- 

 tory. Quarto, v+98 pages, 1 plate, 2 text figures. Published 1911. 

 Price $2.50. 



This publication gives a detailed account of observations and computations 

 made in deriving the solar parallax from photographs of the minor planet Eros 

 taken by means of the Crossley reflecting telescope of the Lick Observatory during 

 the interval October 1900 to January 1901. The value of the parallax deduced is 

 8.8067" 0.0025". 



No. 147. RUSSELL, HENRY NORRIS. Determinations of Stellar Parallax, based upon 

 Photographs taken at the Cambridge Observatory by Arthur R. Hinks 

 and the writer; with Magnitudes and Spectra determined at the Har- 

 vard College Observatory under the direction of Prof. E. C. Pickering. 

 Quarto, vi+142 pages. Published 1911. Price $2.00. 



This work is based on 254 plates of 37 different fields, taken with the Sheep- 

 shanks equatoreal coude of 12 inches aperture and 20 feet focal length. The rela- 

 tive parallaxes of 52 stars especially selected for observation, and of 242 others 

 chosen as objects of comparison, have been determined. Every precaution was 

 taken to eliminate systematic error ; and the discussion of the results for the com- 

 parison-stars indicate that the residual errors whether depending upon a star's 

 position, magnitude, or spectral type, or on the season of the year at which obser- 

 vations were made can not exceed a few thousandths of a second of arc. As 

 regards accidental errors, the results appear also to be of high precision. The con- 



