Barker.] ' 1«U [April 1, 



first annual report has just been issued by Prof. Pickering and con- 

 tains an account of the investigations thus far made, together with tlie re- 

 sults obtained. It is illustrated with a plate (which I have the pleasure of 

 placing before you) illustrating the rapid progress which has been made 

 within the past few years in photographing stellar spectra. The first 

 figure, which is a direct copy of the spectra obtained in 1885, was taken 

 with the Voigtl3,nder lens of two inches aperture having a 30° prism in 

 front of it and shows the spectra of a. Lyr*, « Aquilae, a Bootis and /9 

 and Y Urste Majoris ; the instrument having been directed successively to 

 these stars and the plate exposed five minutes on each. The longest of 

 these spectra is not over four millimeters in length. The second figure is 

 the spectrum f Ursff Majoris accompanied by that of an adjacent fifth 

 magnitude star. It was taken with the larger VoigtlJinder lens, with an ex- 

 posure of five minutes. It is about nine millimeters long and one wide, 

 and illustrates the size of spectra used in preparing the catalogue of spec- 

 tra of the brighter stars, one or two hundred of these being sometimes 

 photographed on a single plate. The third figure represents the spectrum 

 of a Lyrre, and was taken with the Draper eleven-inch telescope with 

 two prisms, on November 5, 1886, with an exposure of fifty-nine minutes. 

 This spectrum is a little more than fifty millimeters long and about two 

 and a half millimeters wide. The fourth spectrum, taken on January 21, 

 1887, represents /? Geminorum. The exposure was fifty minutes, four 

 prisms being used with the eleven-inch Draper telescope. This spec- 

 trum is nearly eighty millimeters long. All these now described are 

 original negatives printed by contact. The fifth figure in this plate 

 represents a little more than half of the spectrum of /5 Geminorum (as 

 given in figure four) enlarged by Prof. Pickering's special process 

 above described. This spectrum is 220 millimeters long and seventy-five 

 wide, and shows a mass of dense lines irregularly distributed. Below this 

 Is a narrow strip, fifteen millimeters wide, of the spectrum of the same 

 star taken on January 12th. It is given for comparison and shows that 

 practically all of the lines shown belong really to the star itself and are 

 not produced in the photographic processes. 



It is gratifying to know that Mrs. Draper has been so well satisfied with 

 these splendid results that she has decided greatly to extend the original 

 plan of the work and to have it conducted in the future on a scale suited 

 to its importance. The attempt will be made to include all portions of the 

 subject so that the final results shall form a complete discussion of the 

 constitution and conditions of the stars as revealed by their spectra, so far as 

 scientific methods at present permit. It is expected that a station will be 

 established in the southern hemisphere, so as to permit the work to be so 

 extended that a similar method of study may be applied to stars in all 

 parts of the sky. The investigations already undertaken include (1) a 

 catalogue of the spectra of all stars north of 24^, of the sixth magnitude 

 or brighter, (2) a more extensive catalogue of spectra of stars brighter 

 than the eighth magnitude, and (3) a detailed study of the spectra of the 



