78 REPORTvS ON invp:stigations and projpxts. 



INVESTIGATIONS OF STELLAR MOTION. 



Boss, Lewis, Dudley Observatory, Albany, New York. Grant No. 



230. (For previous reports see Year Book No. 2, p. xviii, and 



Year Book No. 3, p. 85.) $6,000. 



Report. — Work has progressed effectively since the last report. 



Three assistants and four computers have been regularly employed. 



During the summer just passed four additional assistants have been 



employed on the investigation of errors of graduation of the transit 



circle. 



In the last annual report the operations having in view the prepara- 

 tion of a preliminary general catalogue of bright stars were described, 

 and the intention to complete this during 1905 was expressed. Work 

 on this catalogue was pushed unremittingly, practically to the exclu- 

 sion of everything else, until about May i of the present year. Then 

 the work was temporarily suspended in order to throw the weight of 

 the entire force upon the determination of errors of circle graduation, 

 as hereinafter described. 



The Preliminary General Catalogue of Stars is designed to furnish 

 the positions for igoo, and the deduced proper motions, for every star 

 in the sky, from the north to the south pole of the heavens, which is 

 visible under favorable circumstances to an ordinary eye without the 

 aid of a telescope. In addition to these, nearly as many more stars 

 of somewhat less brightness are included, because they have been 

 frequent subjects of observation in the past. Thus it is designed to 

 include every star to which a statement of motion may be attributed 

 with more than usual precision. There are about 6,000 of these 

 stars. It is thought that this catalogue will temporarily supply a 

 need that has long been felt by astronomical investigators in various 

 lines, and that it will also afford the means for investigation of many 

 stellar problems in a manner more satisfactory than that which has 

 hitherto been possible. Eventually it is hoped to prepare on the 

 same lines a catalogue of all stars down to the seventh magnitude. 

 This work would include the facts relating to nearly 25,000 stars 

 and would furnish a much broader and more satisfactory basis for 

 investigation of problems relating to motion and structure in the 

 sidereal system ; but since the preparation of such a catalogue must 

 still occupy several years, it is thought desirable to present in advance 

 the fundamental part of it (the best-known stars) in the form of a 

 preliminary general catalogue. 



The foundation of the work for each star of the proposed catalogue 

 is now complete. During this year ephemerides were constructed 



