438 ME. J. N. LOCKYEE ON SPECTEOSCOPIC OBSEEVATIONS OE THE SUN. 
“If, then, we conceive that a stratum of cloudy matter surrounds the sun, of which 
the red prominences are the higher portions, the serrated appearance of the long range 
of prominences, seen by Mr. Dawes and Mr. Hind, sufficiently indicates that its general 
surface is exceedingly uneven, presenting the appearance of being covered with numerous 
eminences or ridges. But these irregularities are small when compared with the large 
hook-shaped prominence, and its companion the detached cloud, which were seen by 
most of the observers of the eclipse 
Now, as the spots have been supposed to arise from upward currents causing apertures 
in the sun’s luminous atmosphere, I conceive the higher red prominences, or those which 
remain visible at the middle of the total phase of a central eclipse, may in like manner 
be formed by the same, or similar, currents in the sun’s atmosphere, breaking through 
the envelope of cloud that surrounds him, bending back the edges of the apertures 
they have formed, and sometimes carrying up detached masses of cloud, such as that 
which was seen at the late eclipse. We may, however, suppose the envelope of cloud 
to be sometimes simply raised, without being broken through ; and in that state it may 
form the conical prominences which were observed at the late eclipse. 
“ Since the prominences reflect, they must also absorb light ; and thus the hypothesis 
which has been proposed regarding them assumes the presence of an envelope of cloud 
surrounding the sun’s luminous atmosphere , capable of absorbing part of his light and 
subject to occasional interruptions of its continuity .” 
Mr. Swan thus formally sums up his most important addition to our knowledge of the 
solar envelopes, agreeing with An ago that the Corona is also a solar appendage. We 
have now four envelopes. 
I. The dark cloud below the photosphere. [The cloudy stratum of Hersciiel.] 
II. The photosphere itself. 
III. The envelope of cloud so often referred to. 
IY. The sun’s atmosphere surrounding all, in which the other envelopes may be sup- 
posed to float 
Littrow, who observed the same eclipse, after describing some of the observations, 
goes on to say : — 
“Tout cela me fortifie dans l’opinion concue deja par mon observation seule, que ce 
bord rouge forme une couche environnant toute la photosphere du soleil, et gonflee §a 
et la en protuberances”*. 
Arago in his ‘ Astronomie’f defends his first view, and criticises Mr. Swan’s hypothesis. 
He remarks : — 
“ Tout s’explique dans l’hypothese de nuages flottants dans l’atmosphere diaphane qui 
entoure le soleil. 
“ J’avais cherche de rendre compte des protuberances lumineuses en les assimilant a 
des nuages flottants dans 1’atmosphere diaphane dont je supposais la photosphere 
* Astr. Nachrichten, t. xxxiv. p. 31, and Comptes Eendus, Eeb. 22, 1869. 
t Ed. 1856, t. iii. p. 623. 
