392 
MR. J. EVERSHED OX WAVE-LENGTH DETERMINATIONS, ETC., 
although clearly visiljle, are not nearly so strongly marked as in the corresponding 
negatives of the east limb before totality. 
All the more conspicuous lines Avhich are characteristic of the flash spectrum can 
be distinguished along the south edge of the cusp in Ijoth No. 9 and No. 10 spectra. 
General Results and Conclusions. 
The Flash Spectrum. 
In comparing the wave-length values of No. 3 and No. 7 S 2 :iectra given in Table I. 
with Rowland’s wave-lengths of the absorption lines in the solar spectrum, it is at 
once apparent that practically every strong line in the latter is present in the lower 
chromosphere as a Ijright line. In the region Ijetween XX 3340 and 4410 there are 
58 strong dark lines with an intensity exceeding 8 on Rowland’s scale of intensities. 
In the flash spectrum (No. 3 photograph) 44 of these lines are certainly present as 
bright lines ; 0 are })rohahly pi'esent, 6 are too near to strong hydrogen lines to he 
separately distinguishable, and 1 is obscured l)y H. One line only of the 58 is 
unaccountably absent, that at 3788‘040 (Fe, intensity 9). 
It is further to he observed that of the Ijright lines of the lower chromosphere 
(hydrogen and lielium lines l)eing excluded) the great majority ajjpear to be coinci¬ 
dent with dark lines liaving an intensity on Rowland’s scale not less than 3, and 
two lines only X 3584‘37 and 3812'79 occur in a blank space in the solar spectrum 
where the lines are weaker than intensity 0. 
It may he said generally therefore, with regard to the ultra-violet region, that the 
bright lines of the flash spectrum are reversals of Fraunhofer lines, including all the 
very strong lines (intensity 10 and upwards). 
Whilst the positions of almost all the bright lines appear to coincide with dark 
lines in the solar spectrum, the relative intensities of the lines in the latter are 
widely de^iarted from in the flash spectrum. A negative of No. 3 spectrum is there¬ 
fore very unlike a positive of the solar spectrum. 
When, however, the flash spectrum is analysed into its separate constituents it is 
found that the relative intensities of the lines of any one element correspond very 
closely with the intensities of the dark lines of tliat element. In the ii’on and 
titanium spectra, whicli claim more lines of the flash spectrum than any other 
elements, this correspondence is most clearly shown. There are, as might he 
expected, many cases Avhere tlie intensities are alinoiinal, Init Iw taking tlie average 
intensity on Rowland’s scale of all the dark lines corres})onding to each unit of 
intensity in tlie flash spectrnm the eflects of these are eliminated. These almormal 
intensities are })rol)ahly due to tlie su})erposition of closely adjacent lines. 
The following tables prove the general close correspondence of intensities in the 
flash and solar spectrum for iron and titanium. The first column gives the number 
of flash lines having the estimated Intensity given In column 2, whilst the average 
