1888.] of the various Species of Heavenly Bodies, 



35 



580 — 585, evidently when using a wide slit, while in a later account ot 

 his observations he fixes the wave-length at 580. The line is 

 probably 579, the strongest line of iron at a low temperature. Vogel 

 mentions a bright band extending from 470 to 461 with a maximum 

 between these limits- Pickering measures this as commencing at 

 473. This band is evidently the bright band of carbon commencing 

 at 474, with a maximum about 468 as observed and photographed at 

 Kensington. Between this band and 486 Vogel has shown a dark 

 band in the spectrum. This appearance is due not to any absorption 

 but to the continuous spectrum being short, ending evidently at 486, 

 while the bright carbon appearing beyond this in the blue, leaves 

 a dark band due to absence of radiation. 



Vogel has not noticed any other bright lines, bat Pickering " sus- 

 pected" a brightening at 540. This would be the only line of 

 manganese which appears in the bunsen burner. Vogel may have 

 noticed this line and yet not given any wave-length of it in his list, 

 just as he indicates one bright line in 2nd Cygnus, and two bright 

 lines in 3rd Cygnus in his light curves of those stars, without men- 

 tioning them in any list of bright lines observed. 



Pickering suspected the presence of several other lines, but was 

 unable to obtain any measurements of them. 



Vogel's results are given in the ' Publicationen des Astrophysikal- 

 ischen Observatoriums zu Potsdam,' vol. 4, ]STo. 14, p. 15, and in the 

 sketch at the end of that number. 



Pickering's are in ' The Observatory,' vol. 4, p. 82 ; the ' American 

 Journal of Science and Art,' No. 118, 1880 ; ' Copernicus,' vol. 1, 

 p. 86; and ' Astronomische Nachrichten,' 2376. 



Lalande 13412 — Both Vogel and Pickering have observed the 

 spectrum of this star and have measured the wave-lengths of the 

 bright lines. 



Vogel gives a sketch of the spectrum as well as a list of wave- 

 lengths. 



Vogel mentions a dark band at the blue end of the spectrum, and 

 gives the wave-length in his sketch as from 486 to 473. 

 i Both observers measure the bright 486 hydrogen (F) line. 



Vogel measures a bright line at 540, while Pickering's measure is 

 545; but Pickering in another star, Arg.-Oeltzen 17681. has measured 

 a line at 540, so there can be little doubt that is the correct wave- 

 length. 



Vogel measures a line at 581, but this has not been noticed by 

 Pickering. 



The bright part of the spectrum extending from 473 towards the 

 blue with its maximum at 468 is, I would again suggest, the carbon 

 band appearing beyond the continuous spectrum, the rest of tli3 carbon 



D 2 



