CHAPTERS ON THE 8TAR8. 379 



used. In several catalogues since Bayer, new italic letters have been 

 added by various astronomers. Sometimes these have met with gen- 

 eral acceptance, and sometimes not. 



Flamsteed was the first Astronomer Eoyal in England, and ob- 

 served at Greenwich from 1666 to 1715. Among his principal works 

 is a catalogue of stars in which the positions are given with greater 

 accuracy than had been attained by his predecessors. He slightly 

 altered the Bayer system by introducing numbers instead of Greek 

 letters. This had the advantage that there was no limit to the number 

 of stars which could be designated in each constellation. He assigned 

 numbers to all the brighter stars in the order of their right ascension, 

 irrespective of the letters used by Bayer. These numbers are exten- 

 sively used to the present day, and will doubtless continue to be the 

 principal designations of the stars to which they refer. It is very 

 common in our modern catalogues to give both the Bayer letter and 

 the Flamsteed number in the case of Bayer stars. 



The catalogues by Flamsteed do not include quite all the stars 

 visible to the naked eye, but various uranometries have been pub- 

 lished which were intended to include all such stars. In such cases 

 the designations now used frequently correspond to the numbers given 

 in the uranometries of Bode, Argelander and Heis. 



In recent times these uranometries have been supplemented by 

 censuses of the stars, which are intended to include all the stars to the 

 ninth or tenth magnitude. I shall speak of these in the next section; 

 at present it will suffice to say that stars are very generally designated 

 by their place in such a census. 



There is still here and there some confusion both as to the boun- 

 daries of the constellations and as to the names of a few of the stars in 

 them. I have already remarked that, in drawing the imaginary boun- 

 daries on a star map, as representing the celestial sphere, different 

 astronomers have placed the lines differently. One of the regions 

 in which this is especially true is in the neighborhood of the north 

 pole, where some astronomers place stars in the constellation Cepheus 

 which others place in Ursa Minor. Hence in the Bayer system the 

 same star may have different names in different catalogues. Again, 

 in extending the names or numbers, some astronomers use names which 

 others de not regard as authorative. The remapping of the southern 

 constellation by Dr. Gould changed the boundaries of most of the 

 southern constellations in a way already mentioned. 



I have spoken of the subdivision of the great constellation Argus 

 into four separate ones. Bayer having assigned to the principal stars 

 in this constellation the Greek letters ex, /?, y, etc., the general prac- 

 tice among astronomers since the subdivision has been to continue the 

 designation of the stars thus marked as belonging to the constellation 



