244 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. 
Janssen impatiently waited for the total solar eclipse of 1868, for 
it was to furnish him the opportunity of studying for the first time 
with the spectroscope these solar envelopes. In order to prepare him- 
self in some manner for the observation of this important phenome- 
non Janssen asked that he might be sent, in 1867, to Trani, in Italy, 
to observe an annular eclipse of the sun. His purpose for studying 
the spectrum of the sun during the annular eclipse was to see if he 
could then detect any trace of absorption due to the solar envelopes. 
But he found the spectrum of the annulus the same as that from the 
central part of the sun’s disk. During this same eclipse he unsuc- 
cessfully tried to see the corona. 
But the eclipse of 1868 had in store for him the honor of making 
a great discovery. We know that, after having seen in his spectro- 
scope the brilliant rays of the protuberances, which appeared during 
the totality, that he did not hestitate to affirm, with all the authority 
which his great experience in spectroscopy allowed, that he would 
-be able to see these same rays without an eclipse. On the next day 
he had the joy of confirming his predictions. 
We know that Sir Norman Lockyer made the same discovery 
independently in England, so that the names of these two scientists 
are associated with this so fertile application of spectrum analysis. 
Janssen appeared to realize from the very first day all the importance 
of the discovery which he had just made. Of this we find the proof 
in a letter which he sent to his mother and in which he said: “ I read 
to-day from a book which, until now, was closed to all and from 
which but glimpses could be got during the few short moments of 
a total eclipse.” 
The results obtained from the eclipse of 1868 were too enticing 
for Janssen to stop on the path which he had just opened for 
astronomers, and so he decided to go to Algeria for the total eclipse 
of December, 1870. He was unfortunately prevented from observing 
this eclipse on account of bad weather, but it furnished remarkable 
evidence of his devotion to his work. Apparently imprisoned in 
Paris by the siege, Janssen did not fear to risk the dangers of a 
balloon voyage in order to break through the lines of the enemy. 
This act of courage did more to make him popular than his beauti- 
ful discovery about the prominences and, for the public which 
realized the real dangers of that time in daring a voyage through 
the air, this audacious way of escaping from the beleagured capital 
gave a measure of the devotion to stience of which Janssen was 
capable. Janssen retained from this aerial trip, made under such 
perilous conditions, a sincere love for aerial navigation. Many 
occasions came for proving his interest in this science in giving to 
aeronauts valuable counsel, in consenting to preside over various 
