366 TRANSACTIONS OF SECTION A. 



both these investigations show that very luminous stars are intrinsically some- 

 what bluer than less luminous stars of the same spectral type, the two causes 

 require further research for their disentanglement. The question is of 

 importance, as it may serve in some cases to determine the distances of very 

 remote bodies whose type of spectrum is known. 



It must be admitted that we are as yet very ignorant of the more distant 

 parts of the 'island universe.' For example, we can make little more than 

 guesses at the distance of the Milky Way, or say what part is nearest to us, 

 what are its movements, and so on. But, nevertheless, the whole subject of 

 the Construction of the Heavens has been opened up in a remarkable manner 

 in the last few years. The methods now employed seem competent to produce 

 a tolerably good model showing the co-ordinates and velocities of the stars 

 as well as their effective temperatures and the amount of light they radiate. 

 Industry in the collection of accurate data is required, along with constant 

 attempts to interpret them as they are collected. The more accurate and 

 detailed our knowledge of the stellar system as it is now, the better will be 

 our position for the dynamical and physical study of its history and evolution. 



The following business was then transacted : — 



1. Discussion on Radioactive Elevients and the Periodic Law. 

 Opened by Professor F. Soddy, F.R.S. 



2. Report of the Seismological Committee. — See Eeports, p. 52. 



3. Dr. John Dalfon's Lectures and Lecture Illustrations in Natura,. 

 Philosophy. By Professor W. W. Haldane Gee. 



THURSDAY, SEPTEMBER 9. 



The following business was transacted : — 



1 Discussion on Spectral Classification of Stars and the Order of Stellar 

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



2. Single Line Spectra of the Elements. By Professor J. C. McLennan. 



3. On Prime Numbers. By G. H. Hardy, F.R.S. — See Eeports, p. 350. 



4. Time Space and Relativity. By Professor A. N. Whitehead, F.R.S. 



FRIDAY, SEPTEMBER 10. 

 Th© following business was transacted : 



1. Discussion on Thermionic Emission. 

 Opened by Professor O. W. Eichardson, F.R.S. 



