1888.] of the various Species of Heavenly Bodies, 51 



brighter and wider the bright flutings are the more the dark flutings 

 on either side of them will appear to vary, and in two ways : first, 

 they will dim by contrast when the bright fluting is dimmer than 

 ordinary ; and secondly, the one on the side towards which the bright 

 fluting expands from its most decided edge will diminish as the bright 

 fluting expands. See following diagram. 



Fig. 13. — Diagram showing the variation in width of a bright fluting and the conse- 

 quent variation in width of the contrast band at the fainter edge. 



There is also another important matter to be borne in mind. As 

 these spectra are in the main produced by the integration of the con- 

 tinuous spectra of the meteorites, the bright flutings of carbon, and 

 the dark flutings produced by the absorption of the continuous 

 spectra by the vapour surrounding each meteorite \ the proportion of 

 bright fluting area to dark fluting area will vary with the reduction 

 of the spacing between the meteorites. 



If any bright or dark flutings occur in the same region of the 

 spectrum, when the spaces are greatest, the radiation effect will be 

 stronger, and the absorption fluting will be " masked ;" where they 

 are least the radiation itself will be masked. This reasoning not only 

 applies to flutings but to lines also. 



e 2 



