196 



Mr. J. Norman Lockyer. 



If we are dealing in this case with a single molecule of hydrogen 

 vibrating in a previously unknown way in consequence of a higher 

 temperature, why is it that the molecules of other bodies do not put 

 on similar transcendental vibrations and appear in the same stars so 

 that we shall get new forms of the other chemical elements ? The fact 

 that we do not do so is, T claim, an argument in favour of the view 

 that the principal and subordinate series are produced by molecules 

 of different complexities, and that the finer molecules can alone 

 withstand the action of the highest temperatures. 



In this way we can easily explain the visibility of the new form of 

 hydrogen in connection only or mainly with the lines of the cleveite 

 and other similar gases (for there is already evidence of the existence 

 of other similar gases) in the hottest stars. 



From the admirable work done on such substances as lithium and 

 sodium, which apparently are reduced to their finest atoms at 

 relatively low temperatures, we are bound to consider that when 

 the research includes the complicated spectrum of iron that that 

 also must follow suit ; but it is already obvious that a principal and 

 two subordinate series will never do ; there will be a very long series 

 of series involved. 



Now these series must include both the arc and the enhanced 

 lines, and as these are visible each without the other in stars of 

 different temperatures, in one case associated with the cleveite gases, 

 in another without them, we have another argument in favour of 

 molecular complexity. 



Statement of some Opinions. 



I am glad to know that attention has recently been drawn to the 

 variations in the appearance of the magnesium lines in the celestial 

 bodies by Dr. Scheiner, of the Potsdam Observatory, who is not 

 apparently acquainted with my work of 1879 ; he accepts the idea 

 that the variations furnish us with a precise indication of stellar 

 temperature,* and he is now employing it in the work of the obser- 

 vatory, f 



* ' Astronomical Spectroscopy,' Frost's Translation, p. viii. 



f Dr. Scheiner points out that in the spectra of nearly all stars of Class la 

 (Group 1Y) the line at 4481 " generally appears as a broad line — in some spectra 

 as strong as the hydrogen lines — but its intensity decreases just in proportion as 

 the number of lines in the stellar spectrum increases, so that it is hardly of the 

 average intensity in the solar spectrum, or other spectra of type Ila, and the 

 author is unable to detect it in the spectrum of o Orionis." My prior work, dating 

 from 1879, being probably unknown to Dr. Scheiner, Messrs. Liveing and Dewar 

 are credited with the discovery of the peculiar behaviour of this line in laboratory 

 experiments, and it is added that " the dependence of the line upon the temperature 

 thus readily suggests that the temperature of the absorbing vapours upon the stars 



