83 



3606 



84 



3. Obsei'vations and Comparison Stars. 



The observations were collected from the usual sources 

 and it is believed that all have been included. The published 

 data of observation were checked wherever possible by in- 

 dependent computation and tlie parallax factors and reductions 

 to apparent place were recomputed with the constants of the 

 Berlin Jahrbuch. 



The comparison stars used in the observations are 47 

 in number. Their positions have been investigated with con- 

 siderable care, perhajis with more than is strictly necessary 

 in view of the large probable errors of the observations. 

 It seemed safer however to reduce the errors in the star 

 places as much as possible in order to make them negli- 

 gible as compared with the errors of observation, especially 

 as the case under consideration is one in which the available 

 material is so scanty as to render difficult the attainment of 

 that degree of accuracy which is to be desired. 



I am indebted to Professor Leuschner for much of 

 the star catalogue data obtained by him from the libraries 

 of various observatories while abroad in 1895-96, and to 

 Professor Schaeberle as acting director of the Lick Obser- 

 vatory for his courtesy in allowing me to use the cata- 

 logues at Mt. Hamilton. 



Practically all of the existing catalogues were searched. 

 The catalogue positions wersi reduced to the beginning of 

 the years 1894 and 1895 1ji( Kreutz's tables (A. N. v. 134) 



which are based upon Struve's constants. Systematic cor- 

 rections derived from the introductions to various catalogues, 

 from vol. VII of the Bonner Beobachtungen and from Auwers' 

 papers in A. N. Nos. 3 195-96, 3413-14, and 3463, were 

 applied to reduce to the system of the Astronomische Ge- 

 sellschaft. When systematic corrections could not be found 

 or when they seemed uncertain the simple catalogue position 

 was used. In a few cases however where the total number 

 of observations is large the positions lacking systematic cor- 

 rections were given zero weiglit especially if the observations 

 forming the position were old or few in number. 



The weighting of the catalogues for the formation of 

 the final positions is in accordance with the system published 

 by Davis in his Declinations and Proper Motions of Fifty- 

 six Stars. This system was derived by a consideration of 

 the probable errors of the catalogues concerned, and its 

 homogeneity has been tested by Dr. Davis in the introduction 

 to his paper. Although established primarily fur declinations 

 it has been used for right ascensions as well. A few cata- 

 logues have been used in the |)resent paper which do not 

 appear in the Davis system. Wherever possible these were 

 weighted in accordance with the methods used in forming 

 that system. 



After the reduction of the catalogue positions to the 

 beginning of the year of observation and the application of 

 systematic corrections and weights, the simple mean by; 

 weights was drawn for each comjiarison star unless there 



