Solar Spectrum analogous to the Fixed Lines of Fraunhofer. 363 
map is so adjusted, in the plate, as to have its lines by the 
side of those of Fraunhofer which have the same name. Re- 
ferring, therefore, to the Plate, it will be seen that there are 
beyond the red ray three extra-spectral lines which I have 
marked «, 8, y. ‘These, however, I have only occasionally 
found, for from the general diminution of effect in that region 
they do not always come out in a plain and striking manner. 
None of Fraunhofer’s lines in the yellow and green are given, 
but G and its companions are very strongly marked, as is also 
the group about 7. But by far the most striking in the whole 
tithonograph are those marked H and 4; and now, passing 
beyond the violet, and out of the visible limits of the spectrum, 
four very striking groups make their appearance. ‘The first 
line of each of these groups I have marked in continuation of 
Fraunhofer’s nomenclature, M, N, O, P. In L there are three 
lines, in M five, in N three, in O three, and in P five. 
10. Besides these larger groups the whole tithonograph is 
crossed by hundreds of minuter ones, so that it is utterly im- 
possible to count them. If, as it has been said, nearly 600 
have been counted between A and H, I should think there must 
be quite as many between H and P. In speaking, therefore, 
of these lines as though they were strong individual ones, the 
expression is to be taken with some limitation. It is quite 
likely that each of those bolder lines is made up of a great 
number that are excessively narrow and close together. 
11. If the absorptive action of the sun’s atmosphere be the 
cause of this phenomenon, that action takes place much more 
powerfully on the more refrangible and extra-spectral region. 
The lines exhibited there are bold and strongly developed; 
they are crowded in groups together. 
12, I cannot doubt, judging from analogy, that, by proper 
modes of investigation, similar lines might be detected in the 
calorific extra-spectral region. 
13, The contrast between the visible and tithonographic 
spectra is maintained by the non-appearance of lines in the 
yellow and green regions. Once only I thought I perceived 
a line corresponding to Fraunhofer’s F’, but it was exceedingly 
faint and on the whole doubtful, 
14, Fraunhofer’s lines which occur on the orange, yellow, 
and green spaces, thus leaving no corresponding impression, 
another argument is furnished of the independence of the 
tithonic and Juminous rays. It is probable that more perfect 
arrangements than I have used would give the whole spectrum 
as though it were full of these inactive spaces, and in stating 
that nothing like Fraunhofer’s lines exist in those medial re- 
gions, I therefore simply wish “A to be understood that I can 
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