DEPARTMENT OF MERIDIAN ASTROMETRY. 



179 



index influence the estimated position of the index. The indications 

 are that this influence, which is superimposed upon the personal 

 tendency referred to above, is different for different observers, being 

 very shght for some and more appreciable for other observers. One 

 of the principal effects produced by a large increase in the widths of 

 the lines is to render the estimations more difficult and troublesome. 

 Most observers find it much easier to make the estimations with 

 moderately narrow lines — widths of the order of one-twentieth of the 

 scale interval — than with wide lines. This fact is also brought out 

 by the larger range in the differences "estimated minus measured" 

 and by the increase in the probable error of a single estimation. 



The investigation is being somewhat extended, especially with the 

 view to learning to what extent observers without any previous 

 experience in estimating tenths may acquire and hold a correct personal 

 scale. 



OBSERVATIONS. 



During the year 2,769 observations were taken on 34 nights, with 

 182 supplementary observations on 15 dates for clock, etc. The ob- 

 servations were distributed among the observers as follows: S. 

 Albrecht, 1,263; .\rthur J. Roy, 684; W. B. Varnum, 822. The circle 

 readings for zenith distance showed the following distribution: S. B. 

 Grant, 704; H. Jenkins, 1,225; H. Raymond, 684; C. L. Stearns, 76. 

 In respect to the positions of the instrument these observations were 

 distributed: AE 1,343, AW 1,426. So few stars have less than the full 

 quota of observations that the program can now be considered finished. 



REDUCTION. 



All classes of reductions as enumerated in previous reports have 

 been brought so nearly up to date that some preliminary results on 

 the fundamental stars are being collected. 



The collection of the San Luis observations of the three fundamental 

 observers has been completed and a further investigation for personal 



Differences in declination between observers. 



