1 68 



REPORTS ON INVESTIGATIONS AND PROJECTS. 



These groups afforded the material for the determination of both the effect 

 night minus day, and the term dependent on right ascension. The results 

 from the normal equations follow : 



-^0084 sin a +^0087 COS a. 



Applying these results to the observed clock corrections, clock-rates 

 were computed by the formula A7 = C+^ -\- yt 2 . The rates thus 

 obtained fit the observed clock corrections with a mean probable error of 

 ± ^032. 



These clock corrections are now being applied to all the fundamental 

 stars, to furnish tests. 



REDUCTION OF DECLINATIONS. 



During the past year much labor has been expended upon this branch of 

 the San Luis reductions, but we have not yet reached the final stages. 



For the duplicate series of zenith-distance sheets there have been entered 

 to date the curvature, correction for inclination, correction for flexure, re- 

 fraction, reduction from apparent to mean place, division correction, and 

 feet South minus North. 



The mean places of the fundamental stars as determined from the Pre- 

 liminary General Catalogue have been entered for about half the series on 

 one set of zenith-distance sheets. 



A redetermination of the circle flexure at Albany in November 191 1 

 showed little change in this quantity, and what change there is most probably 

 can be attributed to its indetermination. Three determinations of circle 

 flexure give — 



Circle A. Circle B. 



Albany, 1905 — .51 sin t — .34 cos t — 45 sin t "63 cos t 



San Luis, 1909 — .51 — .31 — .65 .59 



Albany, 1911 — .65 — .31 — .44 .60 



For the telescope flexure the following results have been obtained : 



Teeescope Feexure. 



Albany, 1908 -fi-n 



San Luis, 1909 -j-°-9^ 



San Luis, 191 1 -j-1.11 



Albany, 1911 -f°-98 



Three determinations of the division corrections give : 



