INTRODUCTION 
XXXVII 
With this, working forward from 1900, or backward from 1925, we arrive very 
closely at the same right-ascension for 1910, viz. o h 46® 23^02; whereas if the third 
term had been neglected, there would have been a discrepancy of about ?oi. In 
order to verify the original reduction from 1900 to 1925, compute the effect of the 
third term for 25 years. This is +2^39 (±^j)= ±*037. Including this with the 
effect of annual and secular variation, working either forward or backward, we find 
as the reduction from 1900 to 1925, + 2 m 14*47, exactly that which was found by 
the trigonometrical computation. 
APPENDIX II. 
Appendix II contains the longer notes pertaining to individual stars in the 
Catalogue. These refer chiefly to stars having peculiarities of proper-motion, such 
as periodic proper-motion of each of the components of a binary star. Also for 
two stars, Groomb 1830 and 61 Cygni, the effect of perspective in apparent accelera¬ 
tion, or retardation, of the annual angular motion is discussed and these effects 
have been incorporated in the Catalogue. Further details will be found in the 
notes for those stars. 
As to the stars in relation to which there has been an attempt to trace the path 
of each component around the common center of gravity — the position of which is 
given in the Catalogue — the peculiarities of each case are presented in the notes. 
In general it may be said that only in the case of Procyon was there an attempt 
to use the meridian-observations for determining the form of the real orbit. The 
meridian-observations are not at all suited for this purpose, not only because of 
lack of sufficient accuracy, but still more because of the very great difficulty in 
finding from them the projected focus — the place of the center of gravity. At 
the same time the peri-astron, as well as the orbit generally, was adjusted to bring 
the meridian-observations into comparative harmony with the indications of the 
micrometrical observations. In all other cases the computation was confined to 
the problem of ascertaining the dimensions of the orbit of the principal star, assum¬ 
ing the elements of that orbit, except semi-axis major, to be directly derivable from 
the elements of the orbit described by the fainter around the brighter component. 
The general method employed in computing the orbital motion of each component 
of a binary star around the center of gravity has been outlined in a previous 
chapter of this Introduction, entitled, “ Right-ascensions and Declinations,” pp. 
xxii-xxiv of this Introduction, where also a catalogue of the special determina¬ 
tions is given. 
APPENDIX III. 
In Appendix III are given the latest revised systematic corrections and weights 
of individual star-catalogues adopted in the formation of this General Catalogue. 
The method of deducing these corrections is briefly described in the foregoing Intro¬ 
duction, and is given more in detail in various numbers of Volume XXIII of the 
Astronomical Journal — papers subsequently collected under the title: Catalogue 
of 627 Principal Standard Stars. 
