124 REPORTS OF INVESTIGATIONS AND PROJECTS. 



DEPARTMENT OF MERIDIAN ASTROMETRY* 



Lewis Boss, Director. 



This report covers the year ending September 30, 1907. 



The working staff during this 3^ear has consisted of 4 assistants (men) 

 and 7 computers (women), in addition to the Director. Mr. Arthur J. Roy 

 is first assistant. Mr. WilHam B. Varnum is also employed upon the more 

 responsible parts of the work. During the period when the transit-circle is 

 to be used in the southern hemisphere, this staff will necessarily be much 

 enlarged ; and the funds arising from the current annual appropriations are 

 now being conserved in order to make provision for the temporarily enlarged 

 expenditure which will then be due to this and other causes. 



The most important work of the year has been that which relates to the 

 preparation of the Preliminary General Catalog of 6178 stars, described in 

 the report of this Department for last year (Year Book No. 5, pp. 204-211). 

 Soon after the date of that report the final installment of star-positions deter- 

 mined in 1905-06 at the Royal Observatory of the Cape of Good Hope was 

 received from the Astronomer Royal, Sir David Gill. During the following 

 winter these results, as well as those of the same epoch obtained at the 

 Dudley Observatory for northern stars, were incorporated in the equations 

 of condition for the determination of position and motion for the respective 

 stars, and the final solutions were obtained. At the same time the positions 

 of many of the standard stars were revised where newly published star- 

 catalogs furnished the micans for appreciable improvement. As it stands 

 this catalog of 6178 stars includes essentially all the weight of published 

 observations available up to the present time. 



For each star of this catalog is given the position and proper-motion for 

 1900, together with the elements of precession necessary to reduce the posi- 

 tions to other epochs. Furthermore, are also given the mean epoch of obser- 

 vation for each star, the probable error of the position for that epoch and for 

 1910, as well as the probable error of the annual variation. Thus the 

 Catalog is not only designed to place at the disposal of the reader the most 

 reliable position that it is practicable to compute for a given star at any 

 epoch required, but it aim.s, also, to afford a good quantitative idea of the 

 degree of confidence to which that position is entitled. This constitutes an 

 innovation upon previous practice and should be of advantage in more than 

 one way. For example, if one should deduce any supposed fact in regard 

 to the mutual relations of any of the proper motions of this Catalog, or in 

 regard to residual systematic motions of the stars, he will be able to form a 



* Address : Dudley Observatory, Albany, N. Y. Grants Nos. 368 and 406. $40,000 

 for study of motion and structure of the stellar system of the northern and southern 

 hemispheres. (For previous reports see Year Book No. 2, p. xviii ; Year Book No. 3,.. 

 p. 85; Year Book No. 4, pp. 78-82; and Year Book No. 5, pp. 204-211.) 



