390 COMPARISON OF CATALOGUES OF STARS. 



The first of these catalogues contains the positions of 539 stars, symmetrically 

 distributed over the entire heavens as far as 10° south declination. The authorities 

 upon which the coordinates of these stars depend are as follows : — 



Pulkowa 1845 



Pulkowa 1865 



Pulkowa 1871 



Greenwich 1836-1876 



Harvard College 1871-2 



fLeipsic 1866-1870 



(.Leiden 1864-1870 



The fifth catalogue of the series is to be regarded as a continuation of the first. 

 It depends upon the same authorities as the first, with the addition of the follow- 



ing : 



Cape of Good ITope 1860 



Williamstown 1861-1863 



Melbourne 1870 



Safford ; Harvard College Observations 1862-1865 



Yarnall General Catalogue. 



Washington 1872- 187 o 



The proper motions of the catalogue of 539 stars depend upon a comparison 

 of the modern observations with the unpublished coordinates resulting from a 

 re-discussion of Bradley's observations, by Dr. Auwers. 



The catalogue of Safford extends from 12 hours to 2 hours of right ascension. 

 Since the field operations of the survey by Lieutenant Wheeler were limited to the 

 summer and autumn months, it was necessary to include in the catalogue only such 

 stars as could be made available in this work. The positions given, rest upon the 

 available authorities between 1755 and 1875. The right ascensions are given to 

 hundredths of seconds of time, and the declinations to tenths of seconds of arc. The 

 author considers the right ascensions as provisional only (Introduction, p. 9), but 

 it will be seen hereafter that the agreement with the fundamental system of Auwers 

 is, with a very few exceptions, good, after the systematic differences between the two 

 systems have been applied. For the most part, M'adler's values of the proper motion 

 were employed in the reductions in right ascension. The proper motions in declina- 

 tion depend upon Auwers-Bradley, Piazzi, and Groombridge combined with the 

 modern observations. Bessel's constants of precession were used in the reductions. 



1 In declination only. 



