392 ON THE MEAN PLACES OF 84 FUNDAMENTAL STARS. [48 



due to proper motion, and they are only partially included in the secular 

 variations of precession given by Argelander and Bessel. 



To be rigorously exact, we should take for the value of p 



Secular Variation of Precession from Argelander or Bessel Value of p given in Nautical Almanac. 



Argelander gives the secular variation in his Catalogue; and for stars 

 not in that Catalogue, it may be deduced from the change of precession 

 for 45 years, given in the Fundamenta, bearing in mind that Bessel's 

 precessions in R.A. are expressed in arc. 



From the places thus reduced to 1845 and those given for the same 

 epoch in the Greenwich Catalogue, the final places are to be deduced, 

 giving to each determination a weight proportionate to the number of 

 observations on which it depends. 



The precessions should be calculated for 3 epochs, viz., 1755, 1800 and 

 1845. M. Peters' elements of precession should be employed; these are given 

 by M. Struve in the Astron. Nachr. No. 486, and are founded on Otto 

 Struve's investigations respecting precession combined with Le Verrier's 

 determination of the changes of the plane of the Ecliptic. 



The constants to be employed are : 



For 1755. 

 m = 46"'0495 log n =1 "302430, 



W) Ti 



- = 3-06997 log -0-126339. 



15 15 



For 1800. 

 m=46"'0623 log n = 1 '302346 



^ = 3-07082 log~ = 0-126255 



li) l o 



For 1845. 

 m = 46"'0751 log n =1 '302262, 



777/ W 



= 3-07167 log -^ = 0-126171. 



1*5 1 



