1888.] of the various Species of Heavenly Bodies. 



39 



between this and the 486 line is not due to absorption of the light 

 from the meteorites by any vapour aronnd them, but rather to the 

 absence of any radiation except that from the meteorites themselves 

 at this part of the spectrum. 



The carbon at 564 raises the curve at that point, and this bright- 

 ness with the bright 570 line produces the appearance of a dark 

 space between those wave-lengths, the band beiug simply due to the 

 contrast of a bright fluting and a bright line lying some distance 

 apart on a faint continuous spectrum. There is therefore no 

 absorption of any kind in this star, all the dark bands being due to 

 absence of radiation. 



Of the bright lines two, the 540 and the 558, are due to manganese, 

 540 being the manganese line visible in the bunsen, while 558 is the 

 strongest of the low temperature flutings of manganese. The line 

 at 581, or thereabouts, is most probably the strongest low temperature 

 line of iron. The line at 569 is most probably the green sodium 

 line, while the 486 line is assigned by Yogel to hydrogen. The faint 

 line at 507 has been observed in the flame spectra of several meteor- 

 ites, and is in the exact position of the strongest line of cadmium 

 at the temperature of the bnnsen burner. 



This star, therefore, gives a spectrum, which is short and faintly 

 continuous, due to radiation of meteorites, but has light from carbon 

 added, with a separate band appearing in the blue ; while the strongest 

 low-temperature lines of manganese, iron, and cadmium, with a 

 strong manganese Anting, and the green sodium line, appear bright 

 on the continuous spectrum. There is no absorption of any 

 kind. 



Wolf and Rayet's discovery of bright lines is recorded in ' Comptes 

 Rendus,' vol. 65, p. 292, and confirmed in vol. 68, p. 1470, vol. 69, 

 pp. 39 and 163. Vogel's observations are given in the 1 Publicationen 

 des Astrophysikalischen Observatoriums zu Potsdam,' vol. 4, No. 14, 

 p. 17, and shown in a sketch at the end of that number. 



2nd Cygnus.—B.D. + 35°, No. 4013.— Messrs. Wolf and Rayet, in 

 1867, first observed the spectrum of this star, and measured the 

 positions of the bright lines. Micrometer readings and reference 

 lines are given by them from which a wave-length curve has been 

 constructed. The wave-lengths of the bright lines in the star thus 

 ascertained are > 581 (7), 573 (/3), 540 (£), and 470 O) ; the 

 relative intensities being shown by the Greek letters. They state 

 that : — 



" La ligne est suivie d'un espace obscur ; un autre espace tres- 

 sombre precede a." 



Vogel afterwards examined the spectrum, measured the positions 

 and ascertained the wave-lengths of the bright lines, drew a sketch 



