1891.] 



NEW YOKE ACADEMY OF SCIENCES. 



87 



Let the given quantities be: 



q> = 40° 45', or the latitude of Columbia College. 

 Date = 1886, November 2d, Washington, mean midnight. 



or^ = 2''28'".0 ^2 = 60' 45' «o = 

 a, = S" 10- -0 (5i = 20° 35' 



The tables referred to above are, for the latitude 40° 45' 



From the American Ephemeris : 



G = 2" 7 .9 H= 3" 7.3 i = 6".17 

 log gr= 1.1944 log li = 1.2899 

 We have, then: 



a, = 2" 19'".0, i = + 9 .0, 5o = 40' 40', ? = 20' 5' 



and therefore, from the above little tables, for this pair of stars: 



X = 0.712 k = 0.42 log nu,= 9.8136 

 so that 



kt = + d .8 ao + kt = 2''22"'.8 



g cos {G + oTo) cos t = + 6". 18 

 hiiia cos {H + a^ + kt) cos ? = + 1.55 



ix = + 4.39 



Acp 



+ 12.12 



A calculation of the two stars separately gives for the respec- 

 tive reductions 



10".46 and 13".79 



whose mean is Vl'W'i, agreeing exactly with the result found 

 above. 



AN" INDEX TO " COPERNICUS." AN INTERNATIONAL JOURNAL 



OF ASTRONOMY. 



BY .JOHN TATLOCK, JR., M.A. 



Introduction. 



In 1881 Dr. Ralph Copeland and Dr. J. L. E. Dreyer com- 

 menced the publication of an astronomical journal called 



