XX CARNEGIE INSTITUTION 



it difficult to define specifically the exact amount done under the 

 grant from the Carnegie Institution. The period of nine months, 

 during which the grant has been available, has marked the transition 

 from the routine work of reducing the observed "apparent ' ' positions 

 of the stars to a common ' 4 mean ' ' epoch to the next large step of 

 deducing therefrom the instrumental errors and compiling the final 

 catalogue. This rendered it necessary to spend this time in round- 

 ing out and perfecting all the divers portions of the computations 

 which have been going on uninterruptedly for the past seven years. 

 This has been finished, and also some preliminary work done for the 

 next great and distinct stage of the work : 



(a) To deduce the errors of the telescope for each night of obser- 

 vation. 



(6) To correct all observations for these maladjustments. 



(c) Finally, to combine the definite separate positions into means 

 for each star included in the catalogue, which is the goal of the 

 long labor. 



George E. Hale, Yerkes Observatory, Williams Bay, Wis. Grant 

 No. 13. For measurements of stellar parallaxes, solar photographs, 

 etc. $4, 000. 



Abstract of Report. — Work was begun on the photographic investi- 

 gation of stellar parallaxes early in May with a 40-inch telescope. 

 Up to October, 1 14 plates, containing about 350 exposures, had been 

 obtained. These included : 



(a) Twenty experimental plates. 



(6) Eighty-eight plates suitable for parallax determinations. 



(c) Six plates of loose star clusters. 



Considerable work was also done in the measurement of photo- 

 graphs of star clusters. 



Another line of investigation was the photometric determination 

 of stellar magnitudes. Considerable progress was made in this, 

 fields being measured with the 6-inch reflectors and the 12 and 40- 

 inch refractors. Measures were also made upon the Pleiades group 

 of stars to determine the constant of the equalizing wedge photom- 

 eter. Measurements were also made of comparison stars for faint 

 variables. 



Much progress was also made in the measurement and discussion 

 of photographs of the sun, taken with the spectroheliograph at the 

 Kenwood Observatory in the years 1 892-1 896, and in other minor 

 investigations connected with the work in hand. 



