IO 



NA TURE 



limit at 473. In the light curve Vogel not only shows the 

 582 and 570 lines, but also bright lines in positions which 

 by a curve have been found to correspond to wave-lengths 

 540 and 636. Vogel indicates in his sketch a dark 

 band extending from 486 to the bright band 473, and an 

 apparent absorption on the blue side of the 570 line, this 



[May 3, 1888 



absorption being ended at 564. These two bands agree 

 in position with the dark spaces observed by Messrs. 

 Wolf and Rayet. The bright band in the blue at 473 is 

 most probably the carbon band appearing bright upon a 

 faint continuous spectrum, this producing the apparent 

 absorption from 486 to 473. If the bright carbon really 



Fig. 4. — Map showing the probable origin of the spectrum of Lalande 13412. 



2 3 4 5 6 7 



;0NTINU0U5 SPECTRUM 



HOT CARBON 



MANCANESE LINE 



SODIUM(CREF_IM),, 



LIMERICK METEORITE 



RESULT, 2?PCYGNUS 



VOCELS LIGHT CURVE 



Fig. 5.— Map showing the probable or'gin of the spectrum of Wolf and Rayet's 2nd star in Cygnus. 



KB 



accounts for the appearance of a dark band between the 

 bright 570 and 564 in this star, all the apparent absorp- 

 tion is explained as due to contrast of bright bands on a 

 fainter continuous spectrum due to red-hot meteorites. 



The line at 540 is the only line of manganese visible in 

 the bun sen burner, and the 580 line is the strongest low- 



temperature iron line. The 570 line is most probably the 

 green sodium line 569, the absence of the yellow sodium 

 being explained by the half-and-half absorption and 

 radiation mentioned in the discussion of the causes which 

 mask and prevent the appearance of the lines in a 

 spectrum. 



