186 
NATURE 
| Dec. 21, 1882 
(x.) If the terrestrial elements exist at ‘all in the sun’s atmo- | 
sphere they are in process of ultimate formation in the cooler 
parts of it. | 
(2.) The sun’s atmosphere is not composed of strata which 
thin out, all substances being represented at the bottom ; but of | 
true strata like the skins of an onion, each different in compo-i- | 
tion from the one either above or below. ‘Thus, taking the sun 
in a state of quiescence and dealing only with a section, we shall 
have as shown in (Fig. 1) C say containing neither D nor B, 
and B containing neither A nor C, 
“FiGe 16 
(3.) In the lower strata we have not elementary substances of 
high atomic weight, Aut those constituents of all the elementary 
bodies which can resist the greater heat of these regions. 
4. The conditions under which we observe the phenomena of 
the sun’s atmosphere have not, as a rule, been sufficie itly borne 
in mind, and it is quite possible that the notion of the strata 
thinning out has, to a certain extent, been based more upon the 
actual phenomena than upon reasoning upon the phenomena. 
5. Take three concentric envelopes of the sun’s atmosphere, 
6. Now take three concentric envelopes, A, B, C, so that 
only A restson the photosphere. The phenomena will 7 the 
main be the same as in the former case, z.e. the line C will still 
| appear to rest on the spectrum of the photosphere, for it will be 
| fed, so to speak, fron C’ and C”, though absent along the line 
CBA at Band A. 
7. Thus much having been premised with regard to the 
| observations as conditioned by the fact that we are observing a 
sphere, we can now proceed to note how the two hypotheses deal 
with the facts. 
Spectrum 
Old Hypothesis. 
I. The spectrum of each 
element as seen in our labora- 
New Hypothesis, 
The spectra should xo/ re- 
semble each other. 
' tories should be exactly repre- 
sented in the solar spectrum. 
Fact.—There is a very wide difference between the spect-a. 
Motion should be unequaily 
indicated because the lines are 
due to divers constituents which 
2. Motion in the iron vapour, 
é.g. Ma spot or a prominence, 
should be indicated by the con- 
tortion of all the iron lines exist in different strata accord- 
equally. ing as they can resist the higher 
temperatures of the i) terior 
regions. 
Fact.—The indications show both rest and motion. 
A, B, C, so that C extends to the base of A, and B also to the 
base of A, that is, in both cases to the photosphere. Then, 
whether we deal either with the sphere or a section of it, the 
lengths of the lines in the spectrum of the strata C, B, A will 
give the heights to which the strata extend from the sun, and 
show whether B and A respectively thin out. As the material 
is by hypothesis continuous down to the sun, the lines will be 
continuous down to the spectrum of the sun seen below as 
shown, 
The spectrum of iron in a 
prominence should be vastly 
different from the spectrum of 
iron in a sun- spot, because a 
spot is cooler than a promin- 
ence, 
3. The spectrum of iron ina 
prominence should be the same 
as the spettrum of iron in a 
sun-spot, 
as dissimilar as those of any two 
elements, 
Fact,—The spectra are 
