1891. ] NEW YORK ACADEMY OF SCIENCES. 87 
Let the given quantities be: 
ep = 40° 45’, or the latitude of Columbia College. 
Date = 1886, November 2d, Washington,mean midnight. 
» Aq = 25287.0 62 = 60° 45’ io = 0 
ay = 2710-0 6; = 20° 35’ 
The tables referred to above are, for the latitude 40° 45’ : 
For « and k For log m, 
60s ae | t 6. = 40°40’ | 40° 45’ | 40° 50/ 
0° |+ 0.758 0.00 | — — = Se 
5 c 0.755 ki 0.10 | 0" - 9.8140 | 9.8148 | 9.8155 
10 0.746 0.20 5 9.8138 | 9.8146 | 9.8153 
15 0.732 0.31 10 9.8136 9.8144 9.8151 
20 0.712 0.42 
25 I+ 0.687 0 54 
From the American Ephemeris : 
Goh 73 fee a aa Pc ge Wp 
log g = 1.1944 log h = 1.2899 
We have, then: 
Ay o> LOS he 40; Og 407 4075 EG = 20° db” 
and therefore, from the above little tables, for this pair of stars: 
x = 0.712 k = 0.42 log mo= 9.8136 
so that 
kt=+3 .8 Qo + kt = 2° 227.8 
g cos (G@ + a)cost = + 67.18 
hm) cos (H + a + kt)cos€é = + 1.55 
1 i Sr a} 
Ap = +, 1212 
A calculation of the two stars separately gives for the respec- 
_ tive reductions 
10.46 and 138’.79 
whose mean is 12”,12, 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 
