565th OBDINABY GENERAL MEETING, 



HELD IN THE CONFERENCE HALL, THE CENTRAL HALL 

 WESTMINSTER, ON MONDAY, MARCH 1st, 1915, 

 AT 4.30 p.m. 



The Rev. Prebendary H. E. Fox occupied the Chair at 



THE OPENING OF THE MEETING, AND WAS FOLLOWED BY 



Sir Frank W. Dyson, F.R.S., Astronomer Royal, at 4.45 p.m. 



The Minutes of the preceding Meeting were read and confirmed. 



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

 M.A., B.D., and of the Rev. George Campbell Morgan, D.D., as Members 

 of the Institute. 



The Chairman, the Rev. Prebendary Fox, invited Professor Alfred 

 Fowler, F.R.S., Secretary of the Royal Astronomical Society, and 

 Professor of Physics in the Royal College of Science, to address them on 

 the subject of " The Spectra of Stars and Nebula?." 



The lecture was illustrated throughout by lantern slides. 



THE SPECTRA OF STARS AND NEBULA. 

 By Professor A. Fowler, F.R.S. 



IN this lecture it will be my endeavour to give some indica- 

 tion of the way in which the wonderful power of the 

 spectroscope has been utilized in investigations of the chemistry 

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

 the question of celestial evolution. 



The only intelligible message that a star sends to the earth 

 is borne on its rays of light, and if we are to learn anything at 

 all of the composition and physical state of the star, it must be 

 by the analysis of that light. The spectroscope is an instru- 

 ment which enables us to make such an analysis, by taking- 

 advantage of the dispersive power of a prism or diffraction 

 grating, whereby a complex beam of light is separated into its 

 component parts. 



Before we can understand the language of the spectroscope it 

 is necessary to study very carefully the sources of light which 

 can be artificially produced. If we examine the light from an 

 incandescent solid body, such as a gas mantle or the filament of 



