ASTRONOMY — CAMPBEI,!/. 87 



ments and reductions of 156 spectrograms, made definite measures and 

 reductions of 40 spectrograms, and prepared seven short papers for publi- 

 cation. 



Mr. Burns secured 43 spectrograms with the Mills spectrograph, made first 

 measures and reductions of 100 spectrograms, and definitive measures and 

 reductions of 313 spectrograms. He also completed an extensive study of 

 the orbit of the spectroscopic binary I Andromedae, and his manuscript is 

 now in the printer's hands. 



The one mouth of Dr. Newkirk's service has been devoted to the meas- 

 urement of planetary, lunar, and standard-star plates in order to train his 

 judgment in selecting suitable lines and to acquire fairly constant habits of 

 measurement. 



Experience has demonstrated that this preliminary training can not be 

 neglected. In measuring ordinary and isolated stellar images we have a 

 simple problem in comparison with that of measuring spectral absorption 

 lines whose appearances differ for the various lines in the same star and for 

 the same lines in different stars. There is an embarrassing scarcity of well- 

 trained men and women available for service in this work. At no time has it 

 been possible to secure as many assistants as desired. Good progress has 

 been made, but relatively to the needs of the case it should be more rapid. 



Mr. R. F. Sanford has been engaged since June 18, 1906, as assistant to 

 Professor Tucker in meridian-circle work. He has taken part in computa- 

 tions upon observations of a long list of latitude stars made for the use of 

 Prof. C. Iv. Doolittle, and after acquiring consistent habits of measurement 

 is assisting Professor Tucker in observing his carefully prepared program 

 of stars by fundamental methods. 



(Jj) A grant of $3,000, made in December, 1904, was available for the meas- 

 urement and reduction of Eros photographs, secured by Dr. Perrine with 

 the Crossley reflector, for the purpose of improving our knowledge of the 

 sun's distance from the earth. Miss Fredrica Chase, formerly of Vassar 

 College, and Miss A. M. Hobe, formerly of the Students' Observatory, 

 University of California, have been engaged on this work since December i , 

 1905, under the supervision of Dr. Perrine. Five hundred and twenty-five 

 photographs have been selected as suitable for the investigation. Of these, 

 487 have been measured definitively, and 38 remain to be measured as soon 

 as the comparison stars for them shall have been selected. Half the work 

 of taking differences, forming means, and checking for the plates measured 

 has been done. Extensive auxiliary tables to facilitate the final reductions 

 have been completed and are ready for use. The progress made has been 

 more rapid than was anticipated. The methods employed in this investi- 

 gation are designed primarily for a differential determination of the sun's 

 distance, based upon the Mount Hamilton observations alone ; but second- 

 arily, the measures obtained will be available for combining the Crossley obser- 

 vations with those made at other stations. Mr. A. R. Hinks, chief assistant 



