326 Prof. J. N. Lockyer. On the Photographic [Dec. 



December S, 1892. 



The LORD KELVIN, D.C.L., LL.D., President, followed by Sir 

 JOHN EVANS, K.C.B., D.C.L., LL.D., Treasurer, in the Chair. 



A List of the Presents received was laid on the table, and thanks 

 ordered for them. 



The President announced that he had appointed as Vice -Presi- 

 dents 



The Treasurer. 

 Mr. W. T. Blanford. 

 Prof. Gr. C. Foster. 

 Prof. Lockyer. 



The following Papers were read : 



I. "On the Photographic Spectra of some of the Brighter 

 Stars." By J. NORMAN LOCKYER, F.R.S. Received Novem- 

 ber 3, 1892. 



(Abstract.) 



The present communication consists of a discussion of 443 photo- 

 graphs of the spectra of 171 stars, which have been obtained ab 

 Kensington and Westgate-on-Sea daring the last two years. 



The chief instrument employed in this work has been a 6-inch re- 

 fracting telescope in conjunction with at different times objective 

 prisms of 7J and 45 respectively. 



By this method the time of exposure is short, and good definition, 

 with large dispersion, is easily secured. The spectra thus obtained 

 will bear enlargement up to thirty times without much sacrifice of 

 definition. 



The 30-inch reflector and slit-spectroscope at Westgate-on-Sea have 

 also been used in the inquiry. 



My object has not been so much to obtain photographs of the spec- 

 tra of a large number of stars as to study in detail the spectra of 

 comparatively few. 



In the classifications of stars adopted by others from a considera- 

 tion of the visual observations, only the broader differences in the 

 spectra have been taken into account. Professor Pickering has more 

 recently employed a provisional classification in connexion with the 

 Henry Draper Memorial photographs of stellar spectra, but this 

 chiefly relates to photographs taken with small dispersion. With 



