464 



jVA rURJi 



[March 16, 1899 



S lUthern stars, lliut one of llieiii on tlie poop of llie 

 ship which forms the constellation Argo, hence called 

 f Pappis, contained a system of lines not hitherto recog- 

 nised, and he naturally concluded that it indicated a new 

 element.' On further inquiry he found reason to suppose 

 that this new series was in some way connected with 

 hydrogen, since the lines occupied the same positions as 

 those computed from the same formula and constants 

 from which the ordinary series of hydrogen was calcu- 

 lated, the only difference in the employment of the 

 formula being that even values of n were used instead 

 of odd values. 



Profs. Pickering and Kayser both concede that this 

 new form of hydrogen is due most probably to a high 

 temperature, and Prof. Kayser expressly states " that 

 this series has never been observed before can perhaps 

 be explained by insufficient temperature in our Geissler 

 tubes and most of the stars." 



If, as suggested both by Prof. Kayser and myself, this 

 new series and the one previously known are probably 

 of the subordinate type, the principal series of hydrogen 

 is still beyond our ken, unless indeed one of the still 

 "unknown" lines represents it, as suggested by Prof. 

 Rydberg. Another possibility is that, even in the hottest 

 stars so far considered, the temperature is not high 

 enough to allow its molecule to exist uncombined. 



On the view that the new series of probable hydrogen 

 lines in f Puppis represents the effect of a transcendental 

 temperature, an attempt has been made to produce this 

 spectrum in the laboratory. In the high-tension spark 



his admirable work on the brightest stars of the southern 

 hemisphere, has obtained photographs of the spectrum 

 of y Argus, and on which the new series appears. 



From a discussion of these stars in relation to the 

 others photographed, there can be little doubt that we 

 are here face to face with the very hottest stars so far 

 known, and that the new series of hydrogen lines repre- 

 sents one among the last stages of chemical simplifica- 

 tion so far within our ken. 



We are, therefore, now in a better position to de- 

 termine the relation of this new gas to other gases, both 

 known and unknown, appearing in stars of nearly equal 

 temperature. 



Other Neiv Gas Lines. 



But even with our present knowledge of stellar spectra' 

 we find that in relation to the hottest stars there are still 

 some gaps in our chemical knowledge : not only is this 

 so, but have we any right to assume, taking into account 

 the limitations of our means of observation and of the 

 strict limitation of our observations to the relatively 

 small part of space nearest us, enormous though it is, 

 that we are as yet really in touch with the highest stellar 

 temperatures ? 



Again, we cannot be certain that the small number of 

 stars as yet studied puts us in presence of the highest 

 stellar temperatures. Those stars which apparently are 

 at the very apex of the temperature curve are involved 

 in unknown lines, and require a special study. 



Two typical unknown lines have wave-lengths at 



COMPARISON OF ENHANCCD LINES WITH 

 CHROMOSPHERE AND « CYCNI 



CHROMOSPHERE 



in hydrogen at atmospheric pressure the ordinary series 

 of hydrogen lines is very broad. The use of the spark 

 with large jars in vacuum tubes results in the partial 

 fusion of the glass and the appearance of lines which 

 have been traced to silicium, but the new series has 

 not yet been observed. 



In his first communication. Prof. Pickering mentions 

 lines at 4698, 4652, 4620, and 4505, but he does not refer 

 to them in his second paper, which has special reference 

 to the new series. The line 4505 was at first taken to be 

 one of the components of the new series, but this seems 

 to have been subsc(|uently superseded by the employ- 

 ment of the line about 4544, which agrees better both as 

 regards intensity and the calculated position 45436. 



As this new hydrogen series seems to bear the same 

 relation to the well-known one as the proto-metallic lines 

 bear to the metallic, I call the gas which produces it 

 proto-hydrogen for the sake of clearness. 



The new series of lines discovered by Prof. Pickering 

 has been found in the spectra of f, «, S and k Orionis 

 photographed at Kensington in 1892. 



Prof. Pickering himself has since found this system of 

 lines in other stars than f Puppis, and Mr. McClean, in 



* Stc AitrophyiUal Journal, iv. p. 369. and v. p. 95. 



NO. 1533, VOL. 5q] 



40892 and 4649-2,' and besides these three other \\x. 

 known lines occur in y Argus. 



As these most probably reveal still undiscovered gasc 

 I include them in the following table showing the limit - 



Origii 



Unknown. 



Hydrogen 



(New). 



Unknown. 



Unknown. 



Helium. 



Aslerium. 



Hydrogen. 



4457) 

 4451 ■ 

 1.^876 ) 

 f 45440 

 \ 4200'4 



4089 2 



4649 -2 



f 4471 -6 

 (4026-3 



(4388 



U009 



(Complete 

 V Series. 



Seen only in 7 Argus. 



f Orionis to 7 



Argus, 

 a Crucis to (," 



Orionis. 



Rigel to 7 .-Xrgus 



Rigel to y Arciis 



Aldcbaran to 7 

 Argils. 



No stars avail- 

 able. 



a Kiidani. 

 a Eridani to 7 



Lyr.v. 

 a Eridani to 7 



Lyr.v. 



o Eridani to 



Arclurus. 



I Pnc. Key. St(., vol. Ltii. p. jj. 



