214 



Mr. F. McClean. 



1 



The diagram shows the position of the eight areas consisting 

 of— 



Two upper galactic polar regions, viz., A and AA. 



„ zones „ B „ BB. 



Two lower galactic zones „ C ,, CC. 



polar regions „ D „ DD. 



The galactic zones extend to 30° from the galactic plane. 



The object of the division into equal areas is to bring out roughly 

 any differences of distribution of the different types of spectra in 

 relation to the galactic plane. 



The areas A, B, C, D, and AA are included in the present series 

 of photographs. Of these the first four constitute a complete hemi- 

 sphere, symmetrically divided by the galactic plane, and the deduc- 

 tions as to distribution have been made from them, 



The stellar spectra have been arranged in series, and classed 

 separately in the respective areas to which they belong. It appears 

 at once that Secchi's Type I requires further subdivision into dis- 

 tinct classes. To effect this, a series of divisions in parallel to 

 Secchi's types have been adopted, in which Divisions I, II, and III 

 correspond to Type I, and Divisions IY, V, and VI to Types II, III, 

 and IV respectively. 



Classified tables of the stellar spectra are given, and previous 

 classifications by Secchi, Vogel, Pickering, and Lockyerare indicated 

 in separate columns. 



Three lines of evidence are adduced to show that the helium stars 



