502 Trans. Acad. Sci. of St. Louis. 
even its sign is as yet unknown. Chandler’s periodic law for 
variation of latitude for the meridian of Greenwich, as expressed 
in his formulae (15), (16) and (17) is — 
¢ —¢o=—0".12 cos (t—T,) X 0°.835 —z, OT Oe 
T, = 2406193 (1875 Nov. 1) + 431 E 
r, = 0”.047 + 0”.0037 + 0”.00025z, iO 
[See Ast. Jour. No. 277, Vol. XI, P. 100. 
Tn which — 
9 = the mean latitude. 
the latitude at time ¢. 
the sun’s longitude. 
interval in years, positive after 1875. 
The whole number of times 431 is contained in the 
number of mean solar days between a given date ¢ and 
the epoch Nov. 1, 1875. 
? 
g 
© 
i 
E 
For points not on the meridian of Greenwich this formula 
must be corrected for longitude by adding the longitude 
expressed in arc to the quantities (¢—T,) x 0°.835 and 
© + 10°. 
By this formula, for Columbia, July 17th, 1882, ¢ — % 
= — 0."048, and for July 22d, 1891, g — g, = + 0".222. 
The latitude determination of July 17th, 1882, by Prof. 
Ficklin using Talcott’s Method gave 
g = + 38° 56’ 51”.645 + 0”.108. 
The determination from P. V. Transits by myself, whose 
mean epoch is July 22nd, 1891, gives 
¢ = + 38° 56’ 51.923 + 0”.121. 
Applying the above reductions from mean to true latitude 
with signs changed we get for the two values of the mean 
latitude: of this Observatory: 
Epoch. Observer. Mean Latitude. 
July 17,1882. Ficklin + 38°56’ 51”.69+0".10 
July 22,1891. Updegraff + 38 56’ 51.70+0".12 
