10: COSMICAL ASPECTS OF GEOLOGY.  [Boox I. 
of the elements of which our earth is composed must exist in the 
state of incandescent vapour in the atmosphere of the sun. Thirty- 
two metals have been thus identified, including aluminium, barium, 
manganese, lead, calcium, cobalt, potassium, iron, zine, copper, nickel, 
sodium and magnesium. ‘These elements, or at least substances 
which give the same groups of lines as the terrestrial elements with 
which they have been identified, do not occur promiscuously diffused 
throughout the outer mass of the sun. According to Mr. Lockyer’s 
observations they appear to succeed each other in relation to their 
respective densities. Thus the coronal atmosphere which, as seen in 
total eclipses, extends to so prodigious a distance beyond the disc of 
the sun, consists mainly of subincandescent hydrogen and another 
element which may be new. Beneath this external vaporous en- 
velope lies the chromosphere where the vapours of incandescent 
hydrogen, calcium, and magnesium can be detected. Further 
inward the spot-zone shows the presence of sodium,’ titanium, &e. ; 
while still lower, a layer (the reversing layer) of intensely hot vapours, 
lying probably next to the inner brilliant photosphere gives spectro- 
scopic evidence of the existence of incandescent iron, manganese, 
cobalt, nickel, copper, and other well-known terrestrial metals.' 
It is to be observed, however, that in these spectroscopic researches 
the decomposition of the elements by electrical action was not 
considered. ‘The conclusions embodied in the foregoing paragraph 
have been founded on the idea that the lines seen in the spectrum of 
any element are all due to the vibrations of the molecules of that 
element. But Mr. Lockyer has quite recently suggested that this 
view may after all be but a rough approximation to the truth, and 
that it may be more accurate to say, as a result of the facts already 
acquired, that there exist basic elements common to calcium, iron, 
&e., and to the solar atmosphere. | 
The spectroscope has likewise been successfully applied by Mr. 
Huggins and others to the observation of the fixed stars and nebule, 
with the result of establishing a similarity of elements between our 
own system and other bodies in sidereal space. In the radiation —— 
spectra of nebule Mr. Huggins finds the hydrogen lines very 
prominent ; and he conceives that they may be glowing masses of 
that element. Professor Tait has suggested, on the other hand, that 
they are more probably clouds of stones frequently colliding and 
thus giving off incandescent gases. Sir William Thomson appears 
to favour this view. Among the fixed stars absorption spectra have 
been recognised, pointing to a structure resembling that of our sun, 
viz., an incandescent nucleus which may be solid or liquid or of 
very highly compressed gas, but which gives a continuous spectrum, 
* On spectroscopic research as applied to the sun, see Kirchhoff and Bunsen. Re- 
searches on Solar Spectrum, &c., Macmillan, 1863; Angstrom, Recherches sur le Spectre 
normal du Soleil; Lockyer, Solar Physics, 1873, and Studies in Spectrum Analysis (Inter- 
national Series), 1878; Huggins and, Miller, Proc. Roy. Soc. xii. Phil. Trans. 1864: 
Roscoe’s Spectrum Analysis, with authorities there cited. : 

Pe 


