162 Rutherfurd Photographic Measures of 



4. Argelander's position and proper motion of this star as 

 given in Mittlere Positionen von 160 Sternen have been adopted. 

 For 1874.0 they are : 



a= 23 h o7 m I3 3 .356 n = +o s . 24867 

 6 = 56 28 / 21". 95 fi' = + o".2685 



From these are derived : 



p = 2 // .o7765 = o a .o74i6 x = 82 34' 29" 



The values of P 1 , P 2 , P 5 , and .ST, depending hereon, are in 

 Table YII on page 184; and /S x , S 5 , £ 6 , and S 7 ,are in Table VIII. 



5. For determining the correction for scale- variation, stars 

 numbered 3, 9, 19, 20, 31 and 33 have been used. These are so 

 distributed that 



2s s = 428^6222, 2cos2>= — 0.01, and2ginp= — 0.10 



Therefore the 



Scale variation — K z 9 i? — — — 31 33; s. 



2s« 



This factor of s will be found on page 184. 



6. The correction for orientation variation on page 184 has been 

 deduced in the same manner as described in paragraphs 19-21 of 

 the paper on 61 Gygni, except that Mrs. Davis has reduced the 

 orientation to the mean of all the plates excluding that numbered 

 six, regarding for very obvious reasons the mean of the remaining 

 eleven as nearer the truth than the mean of the entire twelve. 

 Thus the corrections actually applied reduces the orientation to 

 the mean of the remaining eleven plates. The nine stars whose 

 numbers are 8, 9, 10, 11, 14, 16, 17, 20 and 33 after correction for 

 proper motion have been used as standards. They give : 



^ ° = 4- 6.0 and ——2= — 2.3 



2<7 2 ' 2<7 2 



7. For calculating the difference of right ascension and of dec- 

 lination the following constants have been used : 



log P = 0.257799 log S = 9.5094.1 log T = 4-56331 



log Q = 5.1221 log S = 0.0458 log U= 9.4870,! 



Also, by paragraph 24 of Catalogue of Sixty-Jive Stars near 61 

 Gygni. 



n = a sin tt 



m = a cos 7T 



a' — a = Pn + Qnm + Bn 3 + Snm* 



6' — 6 = ffl + W-f Un 2 m 



