SPECTRA OF SOME OF THE BRIGHTER STARS. 
701 
The photographs already taken do not generally extend beyond K, and hence the 
fluting in question is not open to investigation. In the spectrum of Arcturus, however, 
this region has been photographed, and the fluting is apparently present, but its 
intensity does not differ greatly from its intensity in the solar spectrum. 
In a photograph taken by the Brothers Henry two years ago, there is a decided 
darkening in the region of another group of carbon flutings commencing at \4215, 
but this does not appear in the Kensington photographs. 
VII.—DISCUSSION OF STARS IN TABLE C. 
In all the stars included in this Table there is a very considerable amount of 
continuous absorption in the violet, extending to about G. Long exposures are 
therefore required, in order that their spectra may be photographed. The brightest 
star in the Table is a Orionis, and even this requires an exposure of 35 minutes with 
the instrument A to give a spectrum one-tenth of an inch wide, extending to the K 
line. With the 30-inch reflector and slit spectroscope, an exposure of one hour is 
barely sufficient. It is accordingly a matter of considerable difficulty to photograph 
the spectra of these stars, as most of them are below the third magnitude. 
(1.) Sub-division a. 
Characteristics of the Speetr^a. 
Notwithstanding the fact that the visual spectra of these stars are characterised by 
conspicuous flutings, the region more refrangible than F consists almost entirely of 
dark lines. Indeed the only indication of flutings in this region in any of the stars 
named are near wave-lengths 4763 and 4585, and these vary in intensity in the 
different stars. The flutings are stronger in a Herculis than in any of the other stars 
in the Table, as will be seen on reference to Plate 26, and they are still stronger in the 
I spectrum of Mira Ceti, as seen in a photograph kindly forwarded to me by Professor 
Pickering. So far as the line spectrum is concerned, a Orionis may be taken as a 
type of the remainder. Lines of hydrogen, iron, manganese, calcium, chromium, 
cobalt, titanium, and strontium are common to them all. The calcium lines, it will 
be seen, are considerably intensified as compared with the corresponding lines seen in 
the solar spectrum. This applies also to the lines of chromium and manganese, so 
that the spectrum presents a very different appearance from that of the Sun. Many 
of the lines are at present unidentified. There is a remarkable difference in the lines 
at G, the grouping of which is so characteristic of the solar spectrum. This will 
appear from fig. 5. 
