THE AREQUIPA STATION. 517 



Draper, The funds for this research were furnished by Mrs. Draper. 

 From a study of the spectral peculiarities of the stars thus photo- 

 graphed, Mrs. Fleming has discovered a large number of variable stars 

 and several new stars. Charts of the southern sky are made with this 

 instrument each year. This work is in extension of that done in Cam- 

 bridge for the northern sky. This collection is now of great value 

 in tracing the history of any newly discovered celestial object. 



The Bru< e Photographic Telescope. 



A similar but more frequent photographic survey of the sky is 

 also made by means of a Cooke lens with an aperture of about one inch. 

 Photographs are made each month with this instrument of the available 

 sky. An exposure of one hour shows stars to about the eleventh magni- 

 tude, and a plate eight inches by ten covers a region more than thirty 

 degrees square, or about one fortieth part of the whole sky. 



The thirteen-inch Boyden telescope has been used photographically 

 for the detailed study of the spectra of the brighter stars, and for 

 charts of special regions. The power of this instrument is such that, 

 by the use of a battery of two or three prisms, spectra of the bright 

 stars are obtained several inches in length, which show hundreds of 

 lines. By an examination of these spectra several spectroscopic 



