February 19, 1904.] 



SCIENCE. 



297 



tronomer W. H. Wright, who is assisted by 

 Dr. H. K. Palmer. 



The unfortunate delays encountered in 

 completing the mirrors for the reflecting 

 telescope made it unavoidable that the ex- 

 pedition should reach Chile at the begin- 

 ning of the southern winter— the rainy 

 season. San Cristobal was selected as the 

 site early in June. The expedition reached 

 Chile just a few days before the breaking 

 out of very serious labor troubles. This 

 and the storms of winter made the con- 

 struction of the observatory on the summit 

 one of considerable difficulty. The require- 

 ments for erecting the Warner and Swasey 

 steel dome, the reflecting telescope, the elec- 

 tric power line from the valley to the sum- 

 mit, etc., could not be met by skilled labor 

 obtainable in Chile, and the astronomers 

 were called upon to supply this almost en- 

 tirely themselves. 



Up to October 9 spectrograms had been 

 secured for determining the speeds of 

 twenty stars, and ere this the number is 

 undoubtedly much greater. At the time 

 of writing, photographs of the dome, office 

 building and general surroundings have not 

 been received. 



The completion of the extensive installa- 

 tion in the four winter months, in spite of 

 lack of skilled assistance and the frequent 

 interruptions by storms, together with the 

 securing of a considerable number of spec- 

 trograms, is sufficient testimony that nu- 

 merous and valuable results will be secured 

 in the time assigned for the work. 



The Sun's Motion Relative to a Group of 

 Faint Stars: George C. Comstock. 

 A year ago the author presented to this 

 society a set of proper motions of faint 

 stars (ninth to twelfth magnitude, dis- 

 tributed throughout the twenty-four hours 

 of right ascension) determined from micro- 

 metric observations extending over a pe- 

 riod of about half a century. During the 



past year the author derived from these 

 proper motions a determination of the di- 

 rection and magnitude of the sun's motion, 

 using Airy's method for the formation of 

 the necessary equations. This method re- 

 quires that some assumption shall be made 

 with regard to the distance of each star 

 employed, and for this purpose the author 

 used an extrapolation of Kapteyn's for- 

 mula, which represents this distance as a 

 function of the proper motion and stellar 

 magnitude. 



The author has thus derived from abso- 

 lutely new data, no one of the proper mo- 

 tions employed having entered into any 

 previous investigation, the following co- 

 ordinates of the apex of the solar motion: 

 R. A. = 297°, Dec. = -1-28°. 



The mean result of previous determina- 

 tions from brighter stars is 



R.A. = 275'', Dec. = +30°. 



The present solution furnishes as the 

 linear velocity of the sun's motion 4.8 radii 

 of the earth's orbit per annum, which, com- 

 pared with Campbell 's spectroscopic result, 

 4.2 radii per annum, indicates that the 

 assumed parallaxes of the stars are not 

 greatly in error. Adjusting the assumed 

 distances so that the resulting solar velocity 

 shall agree with the spectroscopic deter- 

 mination, the author finds for the average 

 parallax of 67 stars included between the 

 ninth and twelfth magnitudes, n = 0".0051. 



This number, 67 stars, represents the 

 entire amount of data at the author's dis- 

 posal, no proper motion having been re- 

 jected in the discussion, but it is doubtless 

 too small a basis for a determination of 

 the elements of the solar motion and, at 

 least provisionally, the author prefers to 

 interpret the results noted above, as evi- 

 dence that the proper motions obtained for 

 these faint stars are real quantities and 

 that the methods employed for their der- 

 ivation may with advantage receive wider 



