(199 ) 
on each side, so that there is still light of a somewhat considerable 
intensity in the intervening space. 
If the rays whose wave-lengths are less than A are on the average 
of the same intensity as those with wave-lengths greater than A (this 
case is shown in the figure), the „centre of gravity” of the chromosphere 
line is shifted a little to the convex side of the image with respect 
to the place belonging to the absorption line of wavelength A. If, 
on the contrary, we consider the inner limit of the crescent, it 
appears that the line has shifted to the other side. This must involve 
us in difficulties when trying to find the exact wave-length of a 
chromosphere line. 
Moreover, all kinds of variations may be expected in the intensity 
distribution. The ray group whose wave-lengths are greater than A, may 
be intenser or vice versa. In such a case the displacements of the 
chromosphere line, both with regard to limit and to position of centre 
of gravity, may assume quite other values. Such displacements of 
variable character are actually often observed (by CAMPBELL, FROST, 
Lorp ia.) 
The figure represents a case where on the convex side of the 
erescent the intensity of the system decreases faster than on the concave 
side (just otherwise than we should expect from a cursory exami- 
nation; indeed the chromosphere crescent, observed without a spec- 
troscope, is sharply limited on the concave side). This peculiarity 
too has been often seen in the chromosphere spectrum (cf. FRost, 
Astroph. Journ. XII, p. 315, Dec. 1900). In general, many of the 
irregularities in the form of the lines of the chromosphere and the flash, 
as given by Mascari!), CAMPBELL *), Brown °), Lorp*), Frosr ®), 
and also the principal features of the chromosheric spectrum, recently 
once more discussed by Sir Norman Lockyer‘), can be easily 
explained if we suppose the lines to be produced by anomalous 
dispersion. 
A convincing argument for the correctness of our explanation 
would be obtained if it appeared, that all chromosphere lines were 
really double lines of the above described character. 
1) Mascari, Mem. Spettr. 27, p. 88—89; Ref. Naturw. Rundsch, 13, 8, 618. 
2) CAMPBELL, Astroph. Journ. XI, p. 226—233. 
3) Brown, Astroph. Journ. XII, p. 61—63. 
*) Lorp, Astroph. Journ. XII, p. 66—67. 
5) Frost, Astroph. Journ. XII, p. 307—351. 
5) Lockyer, Recent and coming Eclipses, Chapter X and XVIII, London 1900, 
