1889.] Nebulas and Stars with those of Comets and Aurora?. 29 



In cases where any of these higher temperature lines correspond to 

 lines in the comparison spectrum, however, they have been added to 

 the list of cometary lines, in brackets, as sometimes the phenomena 

 compared may attain a temperature slightly higher than that of 

 comets at mean temperature. 



For the nebulae, all the lines recorded in the visible spectrum by 

 Messrs. Huggins, Yogel, Copeland, Taylor, and Fowler are given. 

 The list of lines has been considerably extended since my preliminary 

 discussion of the spectra of nebulae in November, 1887. D 3 and a 

 line at 447 have been observed in the spectrum of the nebula in Orion 

 by Copeland, and Mr. Taylor has also recorded D 3 and lines, or 

 remnants of flutings, at 559 and 520. In the nebula in Andromeda, 

 carbon flutings and the lead flutings at 546 have been observed by 

 Mr. Fowler and confirmed by Mr. Taylor ; since these observations 

 were made, I find that Yogel* has observed a line at 518, probably 

 carbon 51 7, in nebulae numbered in Sir J. Herschel's General Cata- 

 logue 4234, 4373, and 4390. 



Other nebula lines with which I was not previously acquainted 

 are 479, 509, and- 554. All these lines were observed by Yogel in 

 the nebula G.C. 4378.f 



With reference to the appearance of D 3 in nebulae and bright-line 

 stars, I wrote, in November, 1887 J: — "It is right that I should here 

 point out that some observers of bright lines in these so-called stars 

 have recorded a line in the yellow which they affirm to be in the 

 position of D 3 ; while, on the other hand, in my experiments on 

 meteorites, whether in the glow or in the air, I have seen no line 

 occupying this position. 



" I trust that some observer with greater optical means will think 

 it worth his time to make a special inquiry on this point. The argu- 

 ments against this line indicating the spectrum of the so-called helium 

 are absolutely overwhelming. The helium line so far has only been 

 seen in the very hottest part of the Sun which we can get at. It is 

 there associated with b, and with lines of iron which require the 

 largest coil and the largest jar to bring them out, whereas it is stated 

 to have been observed in stars where the absence of iron lines and of 

 b shows that the temperature is very low. Further, no trace of it 

 was seen in Nova Cygni, and it has even been recorded in a spectrum 

 in which C was absent, and once as the edge of a fluting. § 



"It is even possible that the line in question merely occupies the 



* ( Bothkamp, Beob.,' Heft I, 1872, p. 57. 

 f ■ Bothkamp, Beob.,' Heft 1, 1872, p. 57. 

 i ' Roy. Soc. Proc.,' vol. 43, p. 139. 



§ " . . . . The spectrum is very bright : two strong bands are seen in the 

 red, then the D line, followed by a bright line (D 3 ) as the edge of a band . . . ." 

 (Konkoly, " Neuer Bternr bei % Orionis," ' Astr. Nachr.,' No. 2712) . 



