ASTRONOMY — CAMPBELL. I79 



ASTRONOMY. 



Campbell, W. W., Lick Observatory, Mount Hamilton, California. Grants 

 Nos. 421 and 231. (a) Pay of assistants to take part in researches at 

 the Lick Observatory, $4,000. (b) Measurement and reduction of 

 photographic plates of Eros, $3,000. (For previous reports see Year 

 Books Nos. 2, 3, 4, 5, and 6.) $7,000. 



(a) In the spectrographic determination of stellar velocities there have 

 been employed, as assistants in the past year: Miss Leah Allen, October i, 

 1907, to October i, 1908; and Miss A. M. Hobe, July 15, 1908, to October 

 I, 1908. Miss Allen reduced measures of 257 spectrograms made by Dr. 

 Newkirk in the preceding year, measured and reduced 103 spectrograms, 

 computed the "reductions to the sun" for more than 400 spectrograms se- 

 cured within the year, checked the reductions to the sun for about 500 spec- 

 trograms obtained in previous years, and assisted with the records of current 

 observations. 



After acquiring the familiarity and training that is indispensable in taking 

 up this delicate work, Miss Hobe measured and reduced loi spectrograms, 

 and assisted with several minor computations connected with this subject. 



Mr. R. F. Sanford assisted Professor Tucker from October i, 1907, to 

 July I, 1908, with the meridian-circle observations and reductions for de- 

 termining fundamental star positions. Mr. Sanford left the employ of the 

 Observatory in order to serve with Professor Tucker in the work of the 

 Institution at San Luis, Argentina. 



(b) The Crossley reflector photographs of Eros were under measure- 

 ment and reduction during five months of the year by Miss A. M. Hobe 

 and Mrs. J. H. Moore. Their duties in this connection were concluded on 

 July 15. Professor Perrine's time in the past year has been devoted in good 

 measure to determining the most probable value of the solar parallax 

 afforded by these photographs. The results of measurement were combined 

 so as to afford two essentially independent solutions as a check against 

 systematic and computational errors. The resulting values of the parallax 

 are 8.806'' and 8.807". The probable error is ±0.0025". 



The manuscript copy of a proposed volume embodying the essential meas- 

 ures, computed quantities, and results is nearly ready for the printer, but 

 is retained pending a reinvestigation of an apparent periodic inequality in 

 many of the meridian positions of Eros. There are indications that this 

 inequality may be connected in some way with the period of the light varia- 

 tion of Eros, and this possible connection is under consideration. 



