565th ORDINARY GENERAL MEETING, 



HELD IN THE CONFERENCE HALL, CENTRAL HALL, 

 WESTMINSTER, ON MONDAY, MARCH 1st, 1915, 

 AT 4.30 P.M. 



Sib Frank \V. Dyson, F.R.S., Astronomer Royal, took the 



Chair. 



The Minutes of the preceding Meeting were read and confirmed. 



The Secretary announced the election of the Rev. Martin Anstey and 

 the Rev. G. Campbell Morgan as Members of the Institute. 



The Rev. Prebendary H. E. Fox, M.A., opened the Meeting and 

 introduced the Lecturer, Professor Alfred Fowler, F.R.S. 



THE SPECTRA OF STARS AND NEBULJE. By Professor 

 A. Fowler, F.R.S. 



[Abstract.] 



THE purpose of this lecture is to give some indication of the 

 way in which the wonderful power of the spectroscope 

 has been utilised in investigations of the chemistry of 

 stars and nebulae, and of the bearing of such knowledge upon 

 the great question of celestial evolution. 



The only intelligible message that a star sends to the earth is 

 borne on its rays of light, and it is only by the analysis of 

 such light that we can learn anything at all as to the chemical 

 composition and physical condition of the star. Such an 

 analysis has been rendered possible by the invention of the 

 spectroscope in its various forms. Each element, and some com- 

 pounds, has its own distinctive family of spectrum lines or bands, 

 by which it can be identified wherever it occurs in the luminous 

 condition. In opposition to earlier ideas, it is now known that 

 the same substance may give different spectra when excited in 

 different ways. Indeed, one of the most prominent landmarks 

 in the recent history of the interpretation of solar and stellar 

 spectra is the investigation of such changes in passing from 

 the moderate temperature of the electric arc to the violent 

 action of the condensed electric spark, which was first made by 



