OBTAINED AT THE TOTAL SOLAR ECLIPSES OF 1900, 1901 AND 1905. 
449 
Aluminium, magnesium, barium, zinc and lead appear to show the arc lines, but 
not the enhanced lines, or at most very faintly. They are exceptions to the very 
general rule, and the important part the enhanced lines and strong spark lines take 
in the chromospheric spectrum is amply demonstrated for the different metals dis¬ 
cussed wherever it has been possible to compare with both an arc and spark spectrum, 
particularly for titanium, iron, chromium, scandium, yttrium and zirconium. 
The extent of spectrum considered and the accuracy with which the wave-lengths 
have been determined makes the identification of nearly all the brighter lines tolerably 
certain. I have compared the results with those obtained by Sir N. Lockyer, 
Mr. Evershed, Professor Frost, Professor Lord, Dr. Humphreys, Dr. Mitchell 
and Dr. Jewell, and have without scruple availed myself of their opinions of the 
identification of lines which I might otherwise have overlooked. The method of 
identification of lines pursued has been, generally speaking, by comparison with 
the strongest spark lines given by Exner and Haschek. When the enhanced 
lines as given in Sir N. Lockyer’s identification of the chromospheric spectrum 
obtained in the 1898 eclipse are added, the principal lines are well accounted for. 
Spectrum of the Higher Chromosphere. 
At the eclipse of 1905, August 30, the photographs taken for the spectrum of the 
corona contain a number of chromospheric lines. The slit of the spectroscope which 
was set nearly tangential to the sun passed through the large prominence which was 
near the point of second contact. 
The following table gives the observed wave-lengths determined by means of 
Hartmann’s formula. One photograph extends from 4026 to 4501, and the other 
from 4685 to 5875. It will be seen that the helium lines and the line 4685 - 86 are 
stronger in the higher than the lower chromosphere. The enhanced iron lines appear 
to be weakened in the higher chromosphere in comparison with the Mg arc lines and 
the enhanced titanium lines. 
3 M 
VOL. ccvi.—A. 
