1887.] -'■'-'- [Barker. 



bright stars. This hist will include a classification of the spectra, a de- 

 termination of the wave-lengths of the lines, a comparison with terrestrial 

 spectra and an application of the results to the measurement of the ap- 

 proach and recession of the stars. A special photographic investigation 

 will also be undertaken of the spectra of the banded stars and of the ends 

 of the spectra of the bright stars. Beside the instruments already men- 

 tioned, there will be used the twenty-eight-inch and fifteen -inch reflectors 

 constructed by Dr. Draper, which Mrs. Draper has decided to send to 

 Cambridge for this purpose, and also the fifteen-inch refractor belonging 

 to the Observatory. 



From these statements it will appear that photographic apparatus 

 has here been provided on a scale quite unequaled elsewhere. "But," 

 says Prof. Pickering, "Mrs. Draper has not only provided the means 

 for keeping these instruments actively employed, several of them during 

 the whole of every clear night, but also of reducing the results by a 

 considerable force of computors and of publishing them in a suitable 

 form. A field of work of great extent and promise is open, and there 

 seems to be an opportunity to erect to the name of Dr. Henry Draper a 

 memorial such as heretofore no astronomer has received. One cannot but 

 hope that such an example may ])e imitated in other departments of 

 astronomy, and that hereafter other names may be commemorated not by 

 a needless duplication of unsupported observatories but by the more last- 

 ing monuments of useful work accomplished." 



Note added May 1, 1SS7. 



The excellent phototype plate which accompanies and illustrates this 

 paper, shows the enlarged positives of the spectra of a Tauri taken with 

 two prisms and that of o Ceti taken with one. The negatives from which 

 the phototype plate was prepared were kindly furnished me by Prof. 

 Pickering especially for this purpose. My obligations are due to him, 

 therefore, for this courtesy. I am also indebted to ^Mr. Gutekunst for the 

 faithfulness of their reproduction. 



It is a gratifying evidence of appreciation of Prof. Pickering's pho- 

 tographic work, that the National Academy of Sciences, at its meeting in 

 Washington, in April, awarded to him the Henry Draper gold medal, for 

 having in their opinion made the most important progress in Astronomical 

 Physics during the two years which have elapsed since the preceding 

 award. 



Dr. Frazer made the following remarks : 



A question suggests itself in relation to the very important results of Prof. 

 Pickering, which Prof Barker has so lucidlj^ and interestingly described. 



As the extremely minute point of light which is received on the first 

 prism represents the radiation from every part of the star under examina- 

 tion, of course the line of light produced by the prism will represent 

 at any infinitesimal fraction of time, the whole radiation of light from the 



