FAVOURABLE TO THE INVESTIGATION OF PARALLAX. 
349 
The Third Table. — This Table contains the general means of all the observations 
of each star, both in position and distance, reduced to the mean epoch of all the 
observations, which will be found in column three. 
The positions in column four, and the probable errors and weights in columns Jive 
and six, are obtained by combining the means and individual sets (where one set 
only has been obtained at any one period) in accordance with the theory of probabi- 
lities, as above mentioned, except in the case of the four binary stars, in which the 
arbitrary weights are substituted for computed ones, as before explained. 
Where two stars are supposed to be of equal brightness, it has been usual to 
register always the smaller of the two angles, by which the position may be de- 
signated, according as the one or the other component be considered as the larger 
star. 
In these cases there is some confusion as to the identity of the two stars, which 
might be obviated by astronomers agreeing always to designate the northern, or in 
cases of equal N.P.D., the east star as A. 
The seventh and ninth columns contain the sums of the assigned or arbitrary 
weights. 
The eighth column contains the mean of all the observed distances, obtained in all 
cases by using the arbitrary weights. 
The tenth column contains the mean of all the registered magnitudes of each com- 
ponent star, the first No. referring to the brightest of the two components, or in cases 
of equal brightness, to the star called A. 
The eleventh and twelfth columns contain the R.A. and N.P.D. of each star, taken 
from the B. A, C. ; and when the star is not found in that Catalogue, from Struve’s 
of 1837. 
The thirteenth column contains the total number of individual measures in position ; 
the number of measures in distance being equal in every case, except one, that is 
specified, one column suffices for both position and distance. 
In the notes will be found notices of any remarkable differences between the mea- 
sures contained in this Table, and those given by Struve in his Catalogue of 1837 : — 
they are confined to differences exceeding 1° in position, and 0"'200 in distance. 
2 z 
MDCCCLI. 
