1889.] of the various Species of Heavenly Bodies. 185 



Fraunhofer lines. Some of the bright lines observed are described 

 as being to the redward side of dark lines. These are 



547-4, 



542-8, 



539-5, 



536-9, 



582-9, 



526-9 (E), 



517-6. 



In the green there were two bands, one at 560*1, and the other at 

 557, both as broad as the interval of D, which had sharp dark line 

 on their redward sides. 



In all probability these two bands were the first two maxima of the 

 manganese fluting at 558. 



The dark lines which Copeland saw were no doubt partly due to 

 the spectrum of daylight, but some were also due to the absorption 

 taking place in the comet itself. The evidence for this conclusion is- 

 that some of the dark lines recorded in the cometary spectrum are 

 altogether absent, or are exceedingly faint in the solar spectrum. 



Thns there are no dark lines in the solar spectrum to correspond 

 with the dark lines in the spectrum of the comet at 547'4, 539'5, 

 and 517'6. The lines in the spectrum of the comet at 526'9 (E) 

 532*9, 536-9, 542*8, D lt and D 2 , which also occurs in the solar spec- 

 trum, are probably common to both the spectrum of the comet and 

 the daylight spectrum. These are lines which would be likely to 

 appear in the absorption spectrum of the comet, and hence it is 

 highly probable that Copeland observed an integration of the radiation 

 and absorption spectra of the comet and that of daylight. 



A comet gives bright lines at perihelion because there is an action 

 which drives the vapours away from the meteorites. 



The vapours being driven away with great velocity, the lines in 

 their spectra are displaced if the resolved part of the velocity in the 

 line of sight be sufficiently great. The vapours, however, would 

 surround the meteorites at the moment they were produced by the 

 heat due to impacts, and there would therefore be dark absorption 

 lines which would not suffer displacement. The total result would 

 accordingly be bright lines and flutings corresponding to them 

 arranged alongside each other. This, no doubt, was what Copeland 

 observed in the Great Comet of 1882, the vapours of sodium, iron, 

 and lead were being driven away from the earth, the dark lines being 

 on the more refrangible sides of the bright lines, while the man- 

 ganese vapours were driven towards the earth, the dark flutings being 



