144 
POPULAR SCIENCE REVIEW 
the bright lines (though much enfeebled) of hydrogen gas, 
which forms the principal element of the prominences and 
sierra ; the bright green line which has already been noted 
during the eclipses of 1869 and 1870, as well as some other 
fainter lines ; and the dark lines of the ordinary solar spectrum, 
notably that of sodium. These dark lines are much more 
difficult to perceive. These facts prove the existence of matter 
in the sun’s neighbourhood — matter revealing itself in total 
eclipses by phenomena of emission, absorption, and polarisation. 
But the discussion of the facts leads us yet further. Besides 
the cosmical matter independent of the sun, which must exist 
in the neighbourhood of that orb, the observations demonstrate 
the existence of an atmosphere of excessive rarity, mainly 
composed of hydrogen, extending far beyond the chromato- 
sphere and protuberances, and fed from the very matter of 
these — matter erupted with great violence, as we perceive, 
every day. The rarity of this atmosphere, at a certain distance 
from the chromatosphere, must be excessive ; so that its existence 
is not in disagreement with the observations of the passage of 
certain comets close to the sun.” In a letter to Professor De 
La Rive,* Janssen proposes to call the atmosphere which he 
and Respighi have thus independently recognised the coronal 
atmosphere, a title which indicates that it is this atmosphere 
which produces the chief part of those luminous phenomena 
which have been designated hitherto by the name of the solar 
corona. 66 In announcing this result ,” he adds, “ I do not for 
my own part forget all we owe to those labours ivhich have 
prepared the way for it, notably those of the American astro- 
nomers during the eclipses of 1869 and 1870” — a worthy 
-declaration, and likely to remove in a great degree the im- 
pression produced by the somewhat too persistent doubts which 
had been suffered to rest on the accuracy of the results obtained 
by the American observers. 
In the above summary of Janssen’s observations, the chief 
place must be assigned, I conceive, to his recognition of the 
■existence of dark lines in the spectrum of the corona. The fact 
that faint bright lines were perceived other than those belonging 
to hydrogen and the 1474-matter, is interesting and significant, 
while the recognition of the hydrogen lines is an important 
result, the credit of which, however, M. Janssen must share 
with Respighi ; f but the recognition of the dark lines was a 
* “ Bibliotheque Universelle,” January 15, 1872, p. 103. 
t Perhaps also with Mr. Lockyer; hut on this point, until a more exact 
account of his observations has been rendered, I am uncertain. Mr. Lockyer 
has not definitely stated the height at which he recognised the hydrogen 
lines ) and his own statement that he had independently proved the existence 
