114 RECORD OF SCIENCE FOR 1886. 



at the Harvard Observatory. Provision has been made by Mrs. Dra- 

 per for meeting the expenses of this work, as a memorial to her hus- 

 band, the late Dr. Henry Draper. 



Three researches are now in progress. 



The first includes a general survey of stellar spectra. Each spectrum 

 is photographed with an exposure of not less than five minutes, and 

 these photographs generally exhibit the spectra of all stars brighter 

 than the sixth magnitude with sufficient distinctness for measurement. 

 The greater portion of the sky north of —30° has been surveyed in this 

 work, which will be repeated during the coming year. One hundred 

 and fifty-one plates have been measured and 5,431 spectra examined 

 and classified. Of these 4,148 have been identified and the name and 

 position of the corresponding star entered opposite each. The com- 

 pleted work will form a catalogue probably containing three or four 

 thousand stars, each photograjihed on several plates. 



The second research relates to a determination of the spectra of the 

 fainter stars. Each photograi)h taken in the course of this research 

 receives an exposure of one hour, so that the spectra of all the stars 

 not fainter than the eighth or ninth magnitude, and included in a region 

 ten degrees square, are represented upon the plate. On fifty-eight 

 plates 2,416 spectra have been measured, and of these 2,359 have been 

 identified. 



In both of these investigations the 8-inch Bache telescope has been 

 employed. 



The third research relates to a more careful study of the spectra of 

 the brightest stars. For this work Mrs. Draper has lent the 11-inch 

 photographic lens employed by her husband. She has also furnished 

 an admirable mounting for the instrument and a small observatory to 

 contain it. Two prisms have been constructed to i^lace in front of the 

 object-glass, the large one having a clear aperture of 11 inches square 

 and an angle of nearly 15°, the other being somewhat smaller. The 

 preliminary results attained with this apparatus are highly promising. 



A recent photograph of the region in Cygnus where four stars were 

 known, exhibiting the interesting i^eculiarity of bright-line spectra, 

 brought out four more spectra of the same kind. One of these is the 

 comparatively bright star P Cygni, in which bright lines, apparently 

 due to hydrogen, are distinctly visible. This phenomenon recalls the 

 circumstances of the outburst of light in the star T Coronie, especially 

 when the former history of P Cygni Ts considered. According to Schou- 

 feld, it first attracted attention as an apparently new star in 1600, and 

 fluctuated greatly during the seventeenth century, finally becoming a 

 star of the fifth magnitude, and so continuing to the present time. 

 Another of the stars shown by the photograph to have bright lines is 

 DM. + 37°, 3821, where the lines are unmistakably evident. 



