INTRODUCTION 
XIX 
very far from being a catalogue of precision, it does offer a convenient means for 
applying a designation for the great majority of southern stars. Piazzi and Groom- 
bridge with numbers are also convenient designations. Failing all these which 
have been enumerated in the foregoing, the practice has been to employ the number 
in an early catalogue, avoiding those in which there are few stars. If the star occurs 
in no catalogue of precision earlier than about 1875, the number in Lalande’s or 
Bessel’s zones, and occasionally from other sources, has been employed. When, 
as in the case of Piazzi and Lacaille, both numbers exist for the same star, the Piazzi 
number is preferred for stars north of — 30° and the Lacaille number for those 
south of that parallel. It would be tedious, however, to enumerate all the details 
that have governed in the choice of names for stars not frequently observed. 
To the name in the second column is sometimes appended a letter. When m 
is thus appended, it usually means a double star observed in the mass; but where 
the star is wide and the components distinct, or where the components are of nearly 
equal brightness, m more commonly indicates the mean. Usually, the notes give 
an indication as to what is probably meant. For a great proportion of close double 
stars, for which the difference of magnitude between the two components is less 
than 3 m (say), it is rather difficult to determine to what point the observation 
refers. 
For several binaries an attempt has been made to determine the relative masses 
of the components. In such cases the letters c. g. (center of gravity) are appended 
to the name in the second column; the catalogue-position is intended to be that of 
the center of gravity. Particulars relative to such stars are to be found in special 
notes contained in Appendix II. 
MAGNITUDE OF THE STARS. 
The third column on each left-hand page contains the estimated magnitude of 
the star. For all stars indicated as of 6^5 or brighter (with trifling exceptions), the 
magnitudes are taken from a manuscript catalogue furnished by Dr. S. C. Chandler. 
When approached for advice in the matter of star-magnitudes, Dr. Chandler very 
generously offered to place at the disposition of the author the results derivable 
from his extensive manuscripts relating to the magnitudes of the brighter stars. 
This was followed with catalogues containing magnitudes of all stars in either 
hemisphere deemed by Dr. Chandler to be 6^5, or brighter. These were based upon 
the collation of the results from all the principal uranometries and photometric 
results. Furthermore, the “ historic ” or “ natural ” scale (approximately that of the 
Uranometria Nova of Argelander) had been adopted for the normal; and the 
systematic corrections necessary to reduce the Uranometria Argentma and various 
photometries to a normal had also been ascertained. Through the photometric 
observations the normal scale had been fixed at the light ratio whose logarithm is 
0^36. One of the essential features of the historic scale is the magnitude 6^0, which 
in the course of generations, and through the data collected in successive uranome¬ 
tries, had come to be quite a definite thing. In establishing the gradation above and 
below this datum (near Potsdam 6^0) Dr. Chandler appears to have aimed to keep 
