1888.] of the various Species of Heavenly Bodies. 61 



with, more bright lines than indications of absorption ; and, in fact, 

 the chief difference between the spectra of these swarms and of those 

 still sparser ones which we call nebulae lies in the fact that there are 

 a few more bright metallic lines or remnants of flutings; those of 

 magnesium, in the one case, being replaced by others of manganese 

 and iron. 



If my view be correct — if there are stages preceding those recorded 

 by Duner in which we get both dark and bright flutings — it is among 

 bodies with spectra very similar to these that they should be found. 



The first stage exhibited in the objects observed by Duuer is 

 marked by flutings 7, 3, and 2 (omitting the less refrangible one not 

 yet allocated), representing the flutings Mg, Mn, and Fe visible at the 

 lowest temperatures. 



The stars which I look upon as representing a prior stage should 

 have recorded in their spectra the flutings 7 and 3 (without 2), re- 

 presenting Mg and Mn. 



Classification into Species. 



We are now in a position to apply all that has gone before in sum- 

 marised statements of the various spectral changes, including those 

 connected with hydrogen, which take place not only in these objects 

 studied by Duner, but in those others to which I have referred as 

 forming the true beginning of the group. 



The following statements and tables, however, must not be taken 

 as anything else than a first approximation to the real criteria of 

 specific differences. I am convinced that further thought is required 

 on them, and that such further thought will be well repaid. 



The Sequence of the Various Bands in the Spectra of the Elements 

 indicated by Bodies of the Group. 



In comparing the spectrum of an element which has been mapped 

 in the laboratory with the absorption bands in the spectrum of a 

 "star," we need only consider those bands and flutings which stand 

 out prominently and are the first to flash out when there is only a 

 small quantity present. Thus, in the flame spectrum of barium there 

 is an almost continuous background of flutings with a few brighter 

 bands in the green, and it is only important to consider the bands, as 

 the flutings would, mainly produce a general dimming of the continu- 

 ous spectrum. In order to show at a glance what portions of the 

 spectrum of an element it is most important for us to consider in this 

 discussion, I have reconstructed the map of low-temperature spectra 

 which I gave in my previous paper, with reference to those elements 

 which are indicated in the spectra of bodies of Group II. Five orders 

 of intensities are represented, the longest lines, flutings, or bands 



