Dkeyer — On Asf}'onomical Transit Observations. 513 



following table illustrates, but tbey are tbe only ones wbich haye 

 given such a result.* 



Velocity 

 (the equato- 

 rial one = i). 



Personal Error. 



Number of 

 Complete De- 

 terminations. 



1-9 

 1-5 

 1-1 



0-7 



+ 05-141 + 0^-014 

 + 0-120 + 0-010 

 + 0-108 + 0-012 

 + 0-091 + 0-015 



6 

 8 

 5 

 6 



Most probably a velocity greater than the equatorial one was 

 strange to the observer, and therefore more likely to cause an increase 

 of the error. But that personal errors might be quite different in 

 observations of polar stars, has for along time been suspected, not only 

 from Pape's and Peters' observations,! but for many other reasons. 

 We shall here mention only the considerable difference between the 

 determinations of the right ascension of the polar star by Bessel and 

 Struve, which probably arose from a different error for equatorial 

 and for polar stars. "With still greater certainty must such a variation 

 account for the great difference between Struve and Preuss, which 

 appeared through Peters' researches on the right ascension of the 

 polar star, from the observations in Dorpat. We know also from 

 I^ewcomb's "Positions of Fundamental Stars," that the R. A. of the 

 polar star has been found considerably different by the different 

 observers in Washington ; so that, for instance, Mr. Thirion differed 

 more than two seconds from Professor Hall. 



Astronomers who propose the construction of standard catalogues 

 must therefore in future enter more fully than hitherto into an 

 examination of their personal errors. Such a one has lately been 

 undertaken by M. Wagner, Yice-Director of the Russian Central 

 Observatory in Pulkowa, who has been kind enough to communicate 

 to me his important results, of which I shall now, with his permission, 

 give a short account. 



When the chronographic method was introduced in Pulkowa, it 

 was soon found that the right ascensions of polar stars not only 

 depended on the observer's iadividuality, but also on the method of 



* Annales de 1' Observatoire de Paris, viii., p. 187. 

 t The ec^Luation Pape - Peters was : 



Eye-and-Ear. 

 for equatorial stars - O^-ll 

 „ the polar star -0-02 

 (Astron. Nackrichten, liv., p. 187.) 



Chronograph. 

 - 05-14 

 -0-33 



