210 PROCEEDINGS OF THE AMERICAN ACADEMY 



XIV. 



ON THE SOLAR MOTION AND THE STELLAR DIS- 



TANCES. 



• By Truman Henry Safford. 



(Tkird Paper.) 

 Presented, Oct. 12, 1875. 



In previous papers, I have given investigations of this subject, based 

 upon proper motions determined by others. In the present, I give 

 the formulae and tables necessary for the farther prosecution of the 

 subject, in a form slightly different from the ordinary one. In view of 

 previous investigations by Madler and Kovalski, it will be necessary 

 to inquire very minutely into the proper motions whose annual amount 

 is about 0."1. The more swiftly moving stars (as we see them) have 

 been investigated by Argelander and other astronomers, and will be 

 carefully tested : some of them, it is possible, will show a motion not 

 directly proportional to the time, not only because the great circle in 

 which the star appears to move does not meet the successive meridi- 

 ans at angles varying in the manner in which this hypothesis would 

 require, but also because we are nearing or receding from them, rela- 

 tively considered. Thus the terms depending on squares and products 

 of proper motion, which Mr. G. W. Hill has, I believe, first introduced, 

 which are the result of the varied relation between the star's apparent 

 motion and any set of fixed planes, will not perhaps be the only terms 

 of this kind ; so that in such investigations I prefer to omit them and 

 determine by observation the total amount of these terms, following in 

 this matter the example set by Bessel. 



But the proper motions between 0''.1 and 0".2 are susceptible in 

 many cases (not yet studied) of accurate determination from observa- 

 tions now extant ; and in many other cases a few additional observa- 

 tions will be sufficient, so that the work immediately needed is to 

 select from the whole mass such stars of this class as are adapted to 

 either method of treatment. 



