OF SPECTRA AT THE SOLAR ECLIPSE OF JANUARY 22, 1898. 
387 
The continuous spectrum of the corona is strongly marked on this photograph, ljut 
only one true corona line is visible, the green line at X 5303. This line can be traced 
only on the eastern portion of the moon’s limb, and, unlike the cliromosphere arcs, it 
is very variable in intensity, being strongly marked about the position angles 60° to 
70°, and 100°, where the continuous spectrum is also strong, but extremely weak or 
entirely absent in other parts of the limb. 
The results of measures of the corona line on this plate and No. 7 spectra are given 
on p. 401. 
[In the reproductions of the bright-line spectra shown in Plate 11, the position 
angles may be inferred from the fact that the direction of dispersion is also the 
direction of the moon’s path across the sun, the point of second contact (P.A. 56°) 
being at the centre of the arcs on the right-hand side, and third contact (P.A. 236°) 
at tlie centre on the left. The angles are reckoned from the north point through 
east, south, and west. 
The upper edge of each spectrum, therefore, represents the south-east limb, and the 
lower edge the north-w^est limb. The diagram below, showing the prominences in 
their correct positions, will make this clear. The broken lines indicate the positions 
where the green corona line is strongest on the negatives. In the reproductions it 
can be faintly traced on the east liml), where it persists throughout totality, thus 
proving it to be a true coronal radiation, since the chromosphere on this limb was 
entirely hidden l)y the moon after mid-eclipse. 
S=iao° 
In tig. 5 the interi-ujjted coronal arc is perhaj^s best seen ; it almost meets the 
oppositely curved chromosjihere arc Y)'". 
The wave-length scale at the top of Plate 1 1 must be understood as applying only 
to fig. 1, for which it was constructed. The designation of the principal lines in the 
spectra are given underneath fig. 5, at the bottom of the plate. 
3 ]) 2 
