Sept. 6, 1877] 



NA TURE 



401 



spectrum, " because," says Herr Vogel, " he doubtless 

 observed with a spectroscope of too great a power of dis- 

 persion, and therefore many details escaped his notice. 

 This supposition is confirmed by the drawing, published 

 in the Comptcs Rcndus (t. 83, p. 1,172), where M. Cornu 

 represents the spectrum as consisting of two parts, and, 

 which contains no other details besides the bright lines' 

 As the line 588 wave-length, measured in the star spec- 

 trum, csnesponds closely with D3, also the line 531 wave- 

 length, with thewell-known corona line (531,6 wave-lengths) 

 and finally the line 517 wave-length, with the middle of 

 the magnesium lines b, M. Cornu draws the conclusion 

 th\t with regard to chemical composition the atmosphere 

 of the star coincides completely with the chromosphere 

 of our sun : " en resume, la lumifere de I'tftoile parait 

 possdder exactement la mcme composition que celle de 

 I'enveloppe du soleil, nommee chromosphere." Herr 

 Vogel, however, thinks that this conclusion is not alto- 

 geiher justified, since a line (500 wave-length), which 

 does not occur in the chromosphere was distinctly visible 



with the other bright lines in the spectrum, and it 

 eventually became the hriolitesi line of the whole spec- 

 trum. Comparing his own observations with those of 

 M. Cornu, Herr Vogel points out that they agree per- 

 fectly with regard to the presence of the three hydrogen 

 lines, and that of the brightest line of the atmospheric 

 spectrum, or the principal line of the nebute spectrum 

 (500 wave-length). He could not determine the position 

 of the bright green lines with sufficient exactness ; on 

 one day he found for them 527 and 514 wave-lengths 

 respectively, but these figures differ considerably from 

 M. Cornu's ; this is still more the case with the lines in 

 the blue, for which he finds 466 wave-length, while M. 

 Cornu has 451 wave-length. The line 5SS wave-length 

 of M. Cornu was observed by Herr Vogel on one occa- 

 sion, but was not again seen afterwards. 



Father Secchi, in a short note in the Astronomisch: 

 Naclirichten (No. 2,116), says that M. Cornu's description 

 of the spectrum of the new star is correct, with the 

 exception that the bright lines were not indistinct but 



well defined, like lines in spectra of nebula;. Father 

 Secchi observed on January 7 and 8, when Herr Vogel 

 also saw the lines well defined. He is very positive that 

 one of the bright lines is a hydrogen line, another a 

 magnesium line, and a third a sodium line ; this, in Herr 

 Vogel's opinion, is decidedly a mistake, because on 

 January 8 the lines in the vicinity of the magnesium 

 group were quite faint, and no bright line near D was to 

 be seen. According to Herr Vogel, the bright lines which 

 Father Secchi saw were a considerable distance away 

 from the sodium and magnesium groups respectively, 

 their wave-lengths being 500 and 580. 



Mr. Copeland, who worked with a star spectroscope of 

 Herr Vogel's construction, which was connected with the 

 15-inch refractor of Lord Lindsay's observatory, made the 

 first observation on January 2, when the star was of 7th 

 magnitude. He found the spectrum to be remarkably 

 bright and consisting of a faint, continuous spectrum, 

 crossed by five bright lines, of which he determined the 

 following wave-lengths : — (l) 655, intense bright red ; 

 (2) 581, middle of a rather bright band in the yellow, j 



fading off rapidly on both sides ; (3) 504, and (4) 486, 

 bright, well-defined lines ; (5) 456, faint line in the violet. 

 Nos. I and 4 are the hydrogen lines ; No. 3 is the brightest 

 line of the nebulae spectrum. On January 9, when the atmo- 

 sphere was particularly favourable, Mr. Copeland observed 

 two other lines, of 594 and 414 wave-lengths respectively. 

 The first was a " very narrow line," the second " exces- 

 sively faint, but still certainly and repeatedly seen." In the 

 vicinity of about 525 wave-length, Mr. Copeland observed 

 the maximum of intensity of the continuous spectrum. Mr. 

 Copeland's observations agree very well with those of 

 Herr Vogel ; the only exception being the violet line (456) 

 for which Herr Vogel found a greater wave-length. Line 

 414, observed by M. Copeland, may possibly have been the 

 fourth hydrogen line HS, if 414 is not a mistake of the 

 printer and should be 434, as it would be strange if Mr. Cope- 

 land had not seen the third hydrogen line H y (434) which 

 was distinctly visible. Mr. Copeland pointed out that the 

 line of 580 wave-length corresponds closely withalinewhich 

 Herr Vogel observed in the spectra of three faint stars, also 

 belonging to Cygnus, which, have quite abnormal spectra. 



