1895.] On the new Gas obtained from Uraninite. 119 



glimpsed, have already in all probability supplied us with many 

 points of contact between our own planet and the hottest part of our 

 central luminary that we can get at, and stars like Bellatrix, are full 

 of hope for the future, not only in relation to the possibility of more 

 closely correlating celestial and terrestrial phenomena, but in indi- 

 cating that terrestrial chemistry, founded on low density surface pro- 

 ducts in which non-solar gases largely enter, is capable of almost 

 infinite expansion when the actions and reactions of the new order of 

 gases, almost, it may be said, of paramount importance in certain 

 stages of stellar evolution, shall have been completely studied. With 

 regard to the differences indicated between the results of the 

 chromospheric and eclipse observations in the above table, it may 

 be useful to remark that Professor Young's " frequencies," invaluable 

 though they are, must necessarily be of less importance from the 

 present point of view than the eclipse observations obtained, it may 

 almost be said, at the same instant of time. There may be, and 

 doubtless are, two perfectly distinct causes for the appearance of the 

 so-called chromospheric lines. First, the tranquil condition of the 

 lower strata of the sun's atmosphere, which gives us the pure spectrum 

 produced at a constant and the highest that we know of in the sun 

 temperature. Secondly, the disturbed condition which fills the 

 spectrum with lines of a so-called prominence. Formerly it was 

 universally imagined thai the prominences were shot up from below, 

 and, in that case, the lines added would indicate a temperature 

 higher than the normal. But I have sent many papers in to the 

 Society indicating the many arguments against this view,* and to me 

 at the present time this view is almost unthinkable. If these dis- 

 turbance lines are produced from above, they may represent the effect 

 of many stages of lower temperature. Hence a list of chromo- 

 spheric lines loses most of its value, unless the conditions of each 

 observation are stated, and the phenomena appearing at the same 

 place at the same instant of time are recorded. 



Now this same place and same time condition is perfectly met by 

 eclipse photographs, and hence I attach a great value to them ; but 

 the comparison between such eclipse observations and the spectra of 

 certain stars indicates that the latter afford the best criteria of all. 



* They are set out at length in the ' Chemistry of the Sun,' which I published 

 in 1887. 



