122 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



All of the observations were taken with the fixed circle 

 west. Had more time been available the instrument would 

 have been reversed. 



Weights, ranging from 5, the highest, to 1 (occasionally 

 *4), the lowest, were arbitrarily assigned to all the obser- 

 vations. Judgment on a weight was formed from the 

 steadiness of the image during the observation. These 

 weights have been applied all through the reductions. 



j. Reduction of Observations. — The first thing done 

 on the reductions was to take the means of the microscope 

 readings and to apply the micrometer corrections, giving 

 the circle readings (called C in the tables following). 

 The means of the microscopes were checked by taking 

 the difference of every microscope reading from the mean 

 of the four. If the sums of these differences for the two 

 opposite pairs of microscopes was the same, the mean was 

 correct. The corrections for the micrometers were checked 

 by duplicating this part of the work. 



From the readings C the quantity B [equations (II) and 

 (III)] is obtained. The terms A and A' of these equations 

 are obtained from the declinations. 



The declinations have been reduced to 1899.0 by means 

 of the data furnished in Newcomb's Catalogue. The 

 reductions to apparent places were computed by using the 

 Besselian Star Numbers from the American Ephemeris. 

 The factors a', b', c' and d' were computed from the 

 American Ephemeris data. The reductions to apparent 

 places for the first night (June 7) were computed by means 

 of the Independent Star Numbers also. The places for 

 the remaining nights were checked by differences. The 

 apparent declinations are placed in the columns B of the 

 tables given later. 



The following table exhibits the stars' approximate zenith 

 distances and the stars with which they are grouped in the 

 reductions for the refractions : 



