INDUSTRIAL PROGRESS DURING THE YEAR 1876. xxiii 



of an ephemeris, and a discussion of its elements, is under the charge 

 of Professor O. Stone, of the Cincinnati Observatory. 



MOTIONS OF STARS TOWARD OR FROM THE EARTH. 

 The theoretical basis ui)on which rest the recent determinations 

 of the motions of stars in the line of sight, by means of the spectro- 

 scope, has been called in question by Yan der Willigen, in a mathe- 

 matical memoir published some years ago. During the past year 

 Secchi has undertaken to repeat certain measures of Huggins upon 

 several of the brighter stars, and he has found that in his own ob- 

 servations constant errors arose, which masked the true deviations 

 of the stellar lines from their corresponding lines in the comparison 

 spectra. On examining the results obtained by himself, Huggins, 

 Christie, and Vogel, he came to the conclusion that these showed 

 a strong probability that the determinations were affected with 

 constant errors. This was particularly so in the case of Green- 

 wich, nearly all of the results obtained at this observatory show- 

 ing a motion of the star toward the earth. Since the publica- 

 tion of this paper, Christie, of Greenwich, has published a new 

 set of measures, which, in the main, corroborate Muggins's previ- 

 ous determinations ; and Huggins has replied to some strictures 

 by Secchi in a note which describes the delicacy of the research, 

 and states that the difticulties Secchi encountered must be over- 

 come before any trustworthy results are possible, and that Hug- 

 gins himself had successfully avoided these drawbacks. Since 

 the above paragraph was in type, Huggins has communicated to 

 the Royal Society, and Draper to SiUiinan's Journal., accounts of 

 the successful application of photography to the registration of 

 stellar spectra. 



SOLAR MOTION IN SPACE. 



Saflbrd has recently taken up anew the investigation of this ques- 

 tion, using for the purpose Argelander's 250 stars. 



In studying these stars, Professor Safford grouped them by tens, 

 assuming those to be equally distant whose proper motions in arc 

 were nearly equal, and therefore leaving entirely out of considera- 

 tion the brightness of the stars. His first result, as regards the di- 

 rection of the movement of the solar system, was not very different 

 from those of his predecessors ; but there appeared indications that, 

 for each of his groups of stars, the average proper motion Avas in- 

 versely proportional to the average distance ; in other words, that 

 our assumption of stellar distances ought to depend upon proper 

 motions. He concludes that the stars having similar motions espe- 

 cially need study at this time, and that eventually we may hope to 

 use the solar motion as a sort of base to advance our knowledge of 

 stellar distances. 



