716 
PROFESSOR J. N. LOCKYER ON THE PHOTOGRAPHIC 
(h.) There can l^e no question as to the continuous spectrum being brighter in 
bright-line stars than in nebulm. 
(c.) The hydrogen lines also are decidedly less prominent. Indeed thev were 
not recorded at all in the eye observations of y Argus (Arg.-Oeltz., 17681), 
or Wolf and IIayet’s 2nd and 3rd stars in Cygnus,* * * § but they are shown 
in Professor Pickering’s photographs. 
Stars of Increasing Temperature. 
Stage 1.—We should expect the spectra to show : — 
{a.) Absence of bright lines, 
(h.) The presence of dark metallic liutings. 
(c.) The presence of bright carbon liutings. 
{d.) Continuous absorption in the violet. 
We know that there are spectra—those of stars in Table C, Sub-division a —which 
answer these requirements. 
{a.) They show no bright lines under normal conditions, but if the stars are 
variable, the disturbances which bring about the change of luminosity at maximum, 
produce bright lines in the spectrum as in the case of the spectrum of Mira Ceti 
photographed by Professor Pickering. 
[h.) In my discussion of Duner’s observationst I showed that most of the dark 
liutings observed in the part of the spectrum visible to the eye approximated very 
closely to the liutings seen in the llame spectra of manganese, lead, and iron. As 
already stated (p. 702) some of these dark liutings have been photographed at 
Kensington, but they have not yet been completely investigated. 
(c.) In my discussion of D[JNEr’s| eye observations, I also showed that in addition 
to dark metallic liutings we had to deal with radiation liutings of carbon.§ Tlie 
evidence afforded by the photographs has already been referred to (p. 704) and 
although there is now no reason to doubt the actual presence of carbon radiation, 
further photographs are being obtained to carry on the inquiry. 
The stars of this class which have already been photographed at Kensington are 
well advanced in condensation, as indicated by the numerous dark lines, and all the 
liutings, both liright and dark, are conlined to the region less refrangible than G. 
We should therefore not expect to get the more refrangible carbon liutings, as I have 
* ‘ Roy. Soc. Proc.’ vol. 44, pp. 33-43. 
t Ihid., p. 49. 
t Ibid., p. 62. 
§ Subsequent observations by myself and Mr. Fowler seemed to leave no doubt as to the 
