266 Trans. Acad. Sci. of St. Louis. 



Durinorthe years 1885-7, 1 made at the Washburn Observa- 

 tory of the University of Wisconsin with a 5-iuch Repsold 

 meridian circle about 700 observations on more than 100 

 Berliner Jahrhuch stars for the purpose of determining the 

 latitude and the errors of the instrument in decHnation. A 

 description of the instrument, which is one of the finest in 

 the world, may be found in Vol. II. of the Publications of the 

 Washburn Observatory and a detailed account of the manner 

 in which the observations were made is given in Vol. V. of 

 the same Publications. No stars were observed by reflection 

 because the instrument was not provided at that time with 

 apparatus for the purpose. The results were published in 

 Vol. V. of the Publications of the Washburn Observatory in 

 June, 1887. The fact that latitudes vary periodically was not 

 known until four or five years later. In order to give some 

 idea of the accuracy of these observations the results for 

 latitude from the four groups of stars observed, are given 

 below, as published in 1887 (see Publications Washburn 

 Observatory, Vol. V., p. 5* of Appendix), together with the 

 mean epoch of the observations on each group and the quan- 

 tities necessary to reduce the observed latitudes to the mean 

 latitude, quantities computed from Chandler's formula pub- 

 lished in 1892.* 



* See Astronomical Journal, No. 277. 



