NATURE 
321 

THURSDAY, FEBRUARY 23, 1871 


THE MEDITERRANEAN ECLIPSE, 1870 
II. 
N my former article under the above title, written from 
Venice, I gave as shortly as I could the conclusions 
at which I had arrived as to the results of the various 
Eclipse expeditions as gathered from the very imperfect 
information then at my disposal. Since I returned home, 
I have naturally become possessed of more facts, though 
even yet the time has not arrived for discussing all the 
observations as they must be discussed before an absolutely 
final verdict can be given. 
Still, there is so much general interest taken in the 
recent work, that I venture to return to it at the present 
time, more especially as I can now print a letter from a 
distinguished American astronomer, giving his view of 
the work done, and also as I am anxious to refer to Prof. 
Young’s article which has recently appeared in NATURE. 
Prof. Peters, whose long and laborious researches on 
the sun are well known to all of us, thus writes in reference 
“to my former article :— 
“Tts perusal has been to me a source not only of plea- 
sure but of much instruction. You have placed on record, 
with great lucidity, the question as it stood before the 
Eclipse, and the points to be examined by the various 
ways of observation for bringing the question nearer to 
its solution. Although the unfavourable state of the 
weather over the entire zone of totality, as it seems, 
from Spain to Sicily, has greatly obstructed the execu- 
tion of the plans and the extensive preparations made 
with the liberal aid of our respective governments ; and 
although hitherto, of course, only imperfect, mostly verbal, 
information has reached us of what the parties really did 
succeed in obtaining—still the result that is to be drawn 
from the sum total, as you are showing, seems of impor- 
tance. The spectroscopic, polariscopic, and telescopic 
observations altogether agree in demonstrating an interior 
portion of the corona to belong to the sun. The existence 
of such a so/ar stratum is sustained also by my researches 
on the motion of spots when near the limb, pointing to a 
refraction on, or rather above, the sun’s surface. I concur 
further in your opinion that the outer, more irregular radi- 
ating portion of the corona very likely owes its origin to 
our atmosphere. It is highly to be regretted that our 
Etna parties, in elevations respectively of 3,100, 5,500 and 
8,000 feet, suffered disappointment from a heavy cloud at 
the critical moment of totality. Their observations would 
have been decisive as to the local and atmospheric cause 
of the radiating coronal phenomenon.” 
One more extract before I proceed. With reference to 
the suggestion (based on my observations of injections 
into the chromosphere) contained in my article, that 
probably the green line seen in the spectrum of the 
Corona might indicate a new element lighter than hy- 
drogen, Prof. Young, claiming priority in the suggestion, 
‘writes :— 
“In Silliman’s Fournal, November 1869, I wrote, 
“should it turn out that this line in the spectrum of the 
-aurora does actually coincide with 1474, it will be of 
‘interest to inquire whether we are to admit the presence 
-of zvon vapour in and above our atmosphere, or whether 
in the spectrum of iron this line owes its origin to some 
‘foreign substance, probably some occluded gas as yet 
-unknown, and perhaps standing in relation to the mag- 
netic powers of that metal.’ 
“This is the only reference Iam able to make here. 
In my paper published in the Proceedings of the American 
VOL. *U 

Association for 1869, the same thing is, I think, more 
forcibly expressed. I think you will find it also in my 
Eclipse Report in the ‘ Journal of the Franklin Institute’ 
(and in my letter to NATURE last spring). 
“The idea that 1474 might represent some new element 
occurred to me at once when I found it in the Corona, 
but of late I own I have more inclined to the opinion 
that it might possibly be a true iron line, and caused by 
meteoric iron dust of almost infinitesimal fineness ; yet 
I have always felt the difficulty of supposing the com- 
plicated iron spectrum reducible to this one line.” 
I feel it due to Prof. Young to give this extract, though 
I confess I do not see that the suggestions are similar, 
nor do I see anything similar in the letter referred to, 
though I have lighted upon this passage which I had for- 
gotten, which shows the great advance that has been 
made. Prof. Young last year wrote* “ It is not impossible 
that the so-called corona may be complex. Some portion 
of its radiance may, Zerhaps, originate in our own atmo- 
sphere, although I do not yet find myself able to accord 
with the conclusions of Dr. Gould and Mr. Lockyer in 
this respect, and am strongly disposed to believe that the 
whole phenomenon is purely solar.” His present views 
were given to the readers of NATURE three weeks ago, 
as in the main concurring with my own. 
With reference to Prof. Young’s article, 1 am anxious 
to say one word on the “ sudden reversal into brightness 
and colour of the countless dark lines of the spectrum at 
the commencement of totality,” witnessed by himself and 
Mr. Pye. I have seen this once, and only once, during 
all my observations, and Professor Young (who enjoys 
better atmospheric conditions than I do) has never seen 
it when working with the new method. Now, I hold that 
the new method is competent to pick up such an envelope 
as the one referred to by Mr. Longley, if it can pick up an 
uprush similarly composed ; and although of course the 
vapours competent to give such lines are not far off, as 
the ordinary observations prove, I do not think they are 
ordinarily high enough above the level of the photosphere 
to be seen in this manner. That the number of lines is 
largely increased when the atmospheric glare is withdrawn, 
was proved during the American Eclipse. 
But to return to the Corona, the main point of attack 
during the last Eclipse. Since my last article was written I 
have had an opportunity of inspecting copies of the beauti- 
ful photographs taken by Mr. Brothers at Syracuse, and also 
one of the photographs taken by the Americans in Spain, 
These, compared with the sketches taken at the respective 
stations, are very curious, In the Spanish photograph there 
is avery distinct “rift,” or dark space in the coronal region, 
extending, I believe, almost to the sun, and fainter indica- 
tions of two other such rifts in another region, not extend- 
ing so low down in the Corona. So far asthe facts have 
yet been before me, only one of these rifts was sketched. 
Now, at Syracuse Mr. Brothers also photographed rifts— 
three rifts ; but the sketches did not record a single one. 
In Prof. Watson’s drawing, a copy of which I have now in 
my possession, there is no indication whatever of them. 
But there is a much more important factbehind. Of course, 
if these rifts had been in the same positions in the two 
photographs, taken at stations so wide apart as Spain 
and Sicily, the presumptive evidence in favcur of the solar 
nature of the Corona for a distance outside the sun equal to 
* NaTUuRE, Vol. i. p. 533- 
iS) 
