82 PROCEEDINGS OF THE AMERICAN ACADEMY 



FdgJit- Ascensions of Circumpolar and Time Stars, prepared 

 'for the use of the U. S. Coast Survey." He stated that 



This pamphlet contains, — 1st, the right-ascensions and decHnations, 

 for the Mean Equinox of 1855.0, of 48 Circumpolar Stars, or stars 

 within 25° of North Polar Distance, together with their proper mo- 

 tions and the coefficients of all those terms of the precession which 

 became appreciable within one hundred years ; 2dly, the right-ascen- 

 sions, proper motions, annual precessions, and secular variations of 128 

 time-stars, or stars favorably situated for determining time within the 

 latitude of any portion of the United States ; 3dly, the corresponding 

 mean right-ascensions of each of these 176 stars for the beginning of 

 every year, from 1851 to 1863 inclusive. To the fundamental tables 

 are also appended the logarithmic constants for reducing from the mean 

 to the apparent equinox, and their annual variations. The positions 

 of these stars were originally computed in 1854, but have repeatedly 

 since that time been revised and corrected by the introduction of new 

 observations ; and they seem to be the best yet attainable, inasmuch as 

 all observations of a high character which were to be found on record 

 have entered into the determination. For each catalogue or series of 



o 



observations employed, the reduction to the zei'o of Argelander's Abo 

 catalogue has been carefully deduced by the method of least squares, 

 having regard both to constant terms and to terms which are functions 

 of the right-ascension or declination ; the materials being derived, 

 1st, from collation of all stars common to Argelander's catalogue and to 

 the authority under investigation ; and 2dly, where this means was suf- 

 ficient, by indirect comparison through the medium of other catalogues. 



The star-lists in their present form were essentially completed early 

 in 1861, although a few observations have since then been incorporated 

 with the other materials. In March, 1862, manuscript copies were 

 furnished by Professor Bache to the Superintendents of the Washington 

 Observatory and of the American Nautical Almanac, on their respective 

 applications, and these places adopted for use by them ; so that the fun- 

 damental places or zeroes employed for determining time and right- 

 ascensions are now identical in all the national scientific institutions. 



The equinox of 1855.0 was originally selected, because this date, 

 being the semi-decade nearest to the time of computation, was then the 

 most convenient. By a happy coincidence, this epoch is precisely a 

 century later than the epoch of Bradley's observations, as reduced by 



