( 201 ) 
in the following exposures and which is probably owing to a small 
depression in the moon’s edge or to a projecting part of the apparent 
sun’s edge. In the fifth exposure, below the light band so produced 
there appears a similar streak. These bands give so to say repeated 
spectra of the flash (a fortunate circumstance, for the totality was 
over sooner than was calculated and the exposures were thus a 
little later than was intended) so that we obtain at one and the same 
exposure both the pure flash spectrum and the continuous spectrum 
of the sun’s limb. 
Prof. Nyzanp and I have discussed together the possibility of 
ascribing the origin of double lines to disturbing circumstances, such 
as irregular motion of the siderostat, vibrations of the prismatic camera, 
light reflections etc. 1), but we were not able to find any disturbaties 
which could account for the observed phenomena and we must conclude 
that here we really have a property of the chromospheric lines. 
The Fraunhofer lines in the continuous spectrum are weak. This 
may in part be due to the diffusion of light by the clouds. For 
the just appeared edge of the photosphere, which plays the same 
part with the prismatic camera as the illuminated slit with an ordinary 
spectroscope, was not darkly limited, but surrounded by a marked 
aureole (this can be seen in some of our corona photographs). The 
clouds, however, cannot have been the only cause of the faintness 
of the absorption lines in the first stage after totality, this pheno- 
menon having been also observed in a clear sky *). There must therefore 
be another reason for the partial absence of the lines. Our theory 
gives such a reason immediately. For the chromosphere spectrum 
will at the end of totality become more and more like a continuous 
spectrum, because more bright lines will continually appear, each 
of which, according to our hypothesis, forms a double band in which 
the absence of the absorbed waves is not easily perceived. But as 
soon as a portion of the photosphere appears, the already existing, 
apparently continuous spectrum will be dominated by a more really 
continuous spectrum, the source of light of which is limited by two 
nearly sharp edges (those of the photosphere and of the moon). 
In this spectrum the absence of absorbed rays must show in 
the usual way as Fraunhofer lines. The light of the chromospheric 
ares will, of course, partially overlap those lines, but compared with 
1) The mounting of the instruments will be fully discussed in the report of the 
expedition. 
2) CAMPBELL, Astroph Journ. XI, p. 228, April 1900. 
