1889.] of Ike various Species of Heavenly Bodies. 



193 



Hot carbon radiation 



Hot C radiation + 

 Mn radiation. 



Hot C radiation -)- 

 Mn absorption. 



Fig. 13. Encke's Comet (P.P., Dec. 28th, 1871). 

 Cornet III, 1881 (P.P., June 16th), 



uh 2 



HotC + Mil -f- Pb 

 (radiation) . 



Hot C (radn.) + Mi 

 + cool C (absrn.). 



1 Diagram showing the Spectrum of Comet III, 1881, on June 28th and July 27tl 

 showing that absorption occurs nearer to perihelion than radiation. 



days after perihelion passage, the spectrum of the comet consisted of 

 the integrated spectra of hot carbon radiation, and the absorption of 

 cool carbon and manganese, as indicated by the masking of the 

 second and dimming of the first maximum of the citron fluting (see 

 fig. 7). A month later still, the absorption bands disappeared, and 

 the spectrum of the comet consisted of the integration of hot carbon, 

 manganese, and lead radiations. On both occasions the blue band 

 had a maximum at 468. 



In the Great Comet of 1882 we have a good example of the passage 

 of the spectrum from that of manganese and hot carbon radiations 

 to that of hot carbon alone as the comet cooled. The spectrum 

 recorded by Copeland on October 22nd showed the first condition, 



Great Comet of 1882 (P.P., Sept. 17th). 



15. -Diagram showing the Spectrum of the Great Comet of 188J at different dates. 



