ME. J. N. LOCKYEE ON SPECTEOSCOPIC OBSEEVATIONS OE THE SUN. 435 
Eeceived November 26, 1868. 
Additional Note on the Chromosphere. 
Since my last communication to the Eoyal Society I have received, through the kind- 
ness of Admiral Manners, the following extract of a note from Father Secchi, in which, 
although the existence of the new continuous envelope is not announced, important 
corroboration of its existence is contained. Father Secchi says : — 
“Borne, 15 Nov. 1868. 
“ I have been able to verify the observations of Mr. Lockyer on the sun, but I find 
that, even where the lines do not become brilliant, their blackness vanishes by a partial 
inversion. I have found also some luminous lines which become exceedingly brilliant 
near the edge of the sun. One is near the ray D, and the other in contact almost with 
the line B on the side of C. 
“ I find that all around the full limb of the sun the inversion takes place. If the slit 
, of 
10" or 15", but if the slit is parallel to the edge then the inversion is complete. It is a very 
beautiful fact. It is perhaps one that will modify our ideas on the origin of these lines.” 
I have italicized the most important part of the letter. 
Since the 20th of the present month, in consequence of a conversation on that day 
with Mr. De La Eue, I have gone over my observations of the sun’s limb with great 
care, and have also reexamined Mr. De La Eue’s photographs with a view to ascertain 
the evidence which they give of the continuity of the envelope. The result strongly 
confirms my former views. It is true that the photographs do not show a continuous 
chromosphere of anything like uniform thickness ; but that arises from the fact that the 
only part of the sun’s limb where the envelope was visible at all during totality 
happened to be covered by irregular prominences, which were probably very abundant 
at the time. In fact, owing to the relative sizes of the sun and moon during the eclipse 
of 1860, and the direction of the moon’s motion, the top and bottom of the sun’s limb, 
as shown in plate 15 of Mr. De La Eue’s memoir, were considerably within the moon’s 
limb during the totality ; only small portions of the sun’s limb on the preceding and 
the following sides were uncovered, and there the chromosphere is seen to be almost 
continuous, though, as I have said, very irregular. The absolute want of continuity in 
the photographs, which, as far as I recollect, is not observable in Mr. De La Eue’s hand 
drawing, is not a final argument against its real spectroscopic continuity. On the 24th 
of November 1868, when I had an opportunity of observing the sun, I employed the whole 
time in examining into the absolute continuity of the chromosphere; I was enabled, 
until interrupted by clouds, to examine continuously and carefully about 300 degrees 
of the sun’s contour, and during the time I did not for one moment lose sight of the 
chromosphere spectrum. It is very gratifying to find that photographs taken many 
3 M 2 
is perpendicular to the edge the inversion is a very short part, so 
