50 F. W. Very — A Cosmic Cycle. 



exceedingly prolonged series of changes, slowly moving 

 onward to a final dissipation. The great aggregates of elemen- 

 tary, atomic, and molecular movements, which we call suns and 

 planets, may endure ; but the parts of which they are composed, 

 though their existence may comprise ages of the natural life of 

 man, seem to be, in the nature of things, limited both as to 

 time and as to space. A limit in space we see in the respect 

 that matter, as such, is not infinitely subdivisible, but at certain 

 limiting orders of magnitude critical points are reached at which 

 the mode changes, pointing to an ultimate limit of dimension 

 at which matter may be said to originate. 



It would take too long to discuss the rich material, bearing on 

 the subject of atomic resolution, which Sir Norman Lockyer 

 has been accumulating for many years; nor does it seem 

 necessary to do so in this connection, since the present sug- 

 gestion, while deriving support from these valuable observations, 

 is to a certain extent independent of them. 



Lockyer's spectral researches indicate modifications in the 

 spectra of the elements at certain stages of stellar evolution. 

 The whitest stars have extensive outer envelopes of hydrogen 

 and helium, but simplified metallic spectra. Mr. Frank 

 McClean adds oxygen to the list of constituents in the atmos- 

 pheres of the helium stars,* and the photographs of stellar 

 spectra by Sir William and Lady Huggins confirm this, the 

 oxygen triplet {X 4070, 4072, 4076), and the strong nitrogen 

 line, X 3995, appearing plainly in the spectrum of y Orionis, 

 and other lines faintly in this and other stars of McClean's 

 Div. 1, o. The modified spectra which Lockyer attributes to 

 proto-elements, may be phenomena analogous to allotropism, 

 dependent on temperature conditions, but at any rate they 

 demonstrate a lack of fixity in elemental characteristics at tem- 

 peratures which forbid all union of unlike elements, so that the 

 only changes possible are supra-elemental. 



The peculiar spectra of the white stars also show a special 

 arrangement of their constituents, or at least a special condition 

 which prevents the exhibition of a large number of elements. 

 We are thus compelled to include both chemical and physical 

 facts in our classifications. 



Stellar Classifications. 



The arrangement of stars proposed by Mr. Frank McClean 

 contains the essential features of a natural system, and is not 

 too complex for the presentation of a few leading principles. 

 Omitting minor details, we have six groups : Div. 1. Orion 



* " Comparison of Oxygen with the Extra Lines in the Spectra of the Helium 

 Stars, etc." Astrophysical Journal, vol. vii, p. 367, 1898. 



