366 
NATURE 
[Fed. 3, 1870 
travelling load in addition to the fixed load ; and he finds the 
results of the two methods to agree in every respect. 
“Remarks on the recent eclipse of the sun as observed in the 
United States,” by J. N. Lockyer, F.R.S. 
By the kindness of Professors Winlock, Morton, and New- 
ton, I have been favoured with photographs, and as yet un- 
published accounts, of the results of the recent total eclipse of 
the sun observed in America. I am anxious, therefore, to take 
the opportunity afforded by the subject being under discussion, to 
lay a few remarks thus early before the Royal Society. 
‘The points which I hoped might be more especially elucidated 
by this eclipse were as foilows :— 
I. Is it possible to differentiate between the chromosphere and 
the corona ? 
2. What is the real photographic evidence of the structure of 
the base of the chromosphere in reference to Mr. W. De Ja Rue’s 
enlarged photographs of the eclipse of 1860 ? 
3. What is the amount of the obliterating effect of the illumi- 
nation of our atmosphere on the spectrum of the chromosphere ? 
4. Is there any cooler hydrogen above the prominences ? 
5. Can the spectroscope settle the nature of the corona during 
eclipses ? 
With regard to 1, the evidence is conclusive. The chromo- 
sphere, including a ‘‘radiance,” as it has been termed by Dr. 
Gould (the edge of the radiance as photographed being strangely 
like the edge of the chromosphere in places viewed with the open 
slit), is not to be confounded with the corona. 
On this subject, in a letter to Professor Morton, Dr. B. A. 
Gould writes :—‘‘ An examination of the beautiful photographs 
made at Burlington and Ottumwa by the sections of your party 
in charge of Professors Mayer and Haines, and a comparison of 
them with my sketches of the corona, have led me to the con- 
viction that the radiance around the moon in the pictures made 
during totality is not the corona at all, but is actually the image 
of what Lockyer has called the chromosphere. 
“This interesting fact is indicated by many different con- 
siderations. The directions of maximum radiance do not 
coincide with those of the great beams of the corona 8 
they remain constant, while the latter were variable. There isa 
diameter approximately corresponding to the solar axis, near 
the extremities of which the radiance upon the photographs is a 
minimum, whereas the coronal beams in these directions were 
especially marked during a great part of the total obscuration. 
The coronal beams stood in no apparent relation to the pro- 
tuberances, whereas the aureole seen upon the photographs is 
most marked in their immediate vicinity; indeed the great 
protuberance, at 230° to 245°, seems to have formed a southern 
limit to the radiance on the western side, while a sharp northern 
limit is seen on all the photographs at about 350°, the inter- 
mediate are being thickly studded with protuberances which the 
moon displayed at the close of totality. The exquisite masses of 
flocculent light on the following limb are upon the two sides of 
that curious prominence at 93°, which at- first resembled an ear 
of corn, as you have said, but which, in the later pictures, after 
it had been more occulted, and its southern branch thus rendered 
more conspicuous, was like a pair of antelope’s horns, to which 
some observers compare it. Whatever of this aureole is shown u pon 
the photographs was occulted or displayed by the lunar motion, 
precisely as the protuberances were. The variations in the form 
of the corona, on the other hand, did not seem to be dependent 
in any degree upon the moon’s motion. The singular and elegant 
Structural indication in the special aggregations of light on the 
eastern side may be of high value in guiding to a further know- 
ledge of the chromosphere. They are manifest in all the photo- 
graphs by your parties which I have seen, but are especially 
marked in those of shortest exposure, such as the first one at 
Ottumwa. In some of the later views they may be detected on 
the other side of the sun, though less distinct ; but the very 
irregular and jagged outline of the chromosphere, as described 
by Janssen and Lockyer, is exhibited in perfection.” 
2. The second point is also referred to in the same letter. Ithink 
the American photographs afford evidence that certain appear- 
ances in parts of Mr. De la Rue’s photographs, which represent 
the chromosphere as billowy on its under side, are really due to 
Some action either of the moon’s surface or of a possible rare 
lunar atmosphere, so tliat it is not desirable to confound these 
effects with others that might be due to a possible suspension 
of the chromosphere in transparent atmosphere, if only a section 
of the chromosphere were photographed, 
Dr. Gould writes:—‘* You will observe that some of the 
brighter, petal-like flocculi of light have produced apparent 
indentations in the moon’s limb at their base, like those at the 
bases of the protuberances. These indentations are evidently 
due to specular reflection from the moon’s surface, as I stated to 
the American Association at Salem last month. Had any doubt 
existed in my mind previously, it would have been removed by 
an inspection of the photographs. ” 
Where the chromosphere is so uniformly bright that the actinic 
effect on the plate is pretty nearly equal, the base of the chromo- 
sphere is absolutely continuous in the American photographs ; 
but in the case of some of the larger prominences, notably those 
at + 146 (Young) and — 130 (Young), there are strong apparent 
indents on the moon’s limb. 
3. I next come to the obliterating effect of the illumination of 
our atmosphere on the spectrum of the chromosphere. 
This is considerable ; in fact, the evidences of it are very much 
stronger than one could have wished, but hardly more decided 
than I had anticipated. Professor Winlock’s evidence on this 
point, in a letter to myself, is as follows :—‘* T examined the 
principal protuberances before, during, and after totality. I saw 
three lines (c, near D and F) before and after totality, and eleven 
during totality; eight were instantly extinguished on the Sirst 
appearance of sunlight.” 
This effect was observed with two flint prisms and seven inches 
aperture. Professor Young, with five prisms of 45° and four 
inches aperture, found the same result in the part of the spectrum 
he was examining at the end of the totality. 
He writes:—“TI had just completed the measurements of 
2,602, when the totality ended. Zs Zine disappeared instantly, 
but 2,796 [the hydrogen line near G] was nearly a minute in 
resuming its usual faintness.” 
These observations I consider among the most important ones 
made during the eclipse; for they show most unmistakably that, 
as I have already reported to the secretary of the Government- 
Grant Committee, the new method to be employed under the 
best conditions must be used with large apertures and large dis- 
persion. 
On the 4th point the evidence is negative only, and there- 
fore in favour of the view I have some time ago communicated 
to the Royal Society. 
5. We next come to the question of the corona, a question 
which has been made more difficult than ever, in appearance only, 
I think, by the American observations. 
I propose to discuss only the spectroscopic observations of 
Professors Young and Pickering in connection with Dr. Gould’s 
before-quoted remarks, : 
[After this discussion, for which we have not space, the author 
continues :—] 
I have first to do with the continuous spectrum, deduced 
from Professor Pickering’s observations. 
I think in such a method of observation, even if the corona 
were terrestrial and gave a dark line spectrum, the lines visible 
with such a dim light would in great part be obliterated by the 
corresponding bright lines given out by the long are of chromo- 
sphere visible, to say nothing of the prominences, in which it 
would be strange if C, D, E, 2, F, and many other lines were 
not reversed. This suggestion, I think, is strengthened by the 
Statement that two bright lines were seen ‘near C” anc “near 
E;” should we not rather read (for the ‘‘near” shows that we 
are only dealing with approximations) C and F, which is exactly 
what we might expect ? 
But even this is not all that may be hazarded on the subject 
of the continuous spectrum, which was also seen by Prof. Young 
under different conditions, 
Assuming the corona to be an atmospheric effect merely, as I 
have before asserted it to be, in part at least, it seems to me that 
its spectrum should be continuous, or nearly so ; for is it not as 
much due to the light of the prominences as to the light of the 
photosphere, which it may be said roughly are complementary 
to each other ? 
With regard to the aurora theory, I gather from Prof. Young’s 
note that, if not already withdrawn, he is anxious to wait till the 
next eclipse for further facts. I consider the fact that I often 
see the line at 1,474, and often do not, is fatal to it, as it should 
be constantly visible on the proposed hypothesis. The observa- 
tion of iron-vapour, as I hold it to be at this elevation, is of ex- 
treme value coupled with its simple spectrum, seez during an 
eclipse, as it entirely confirms my observations made at a lower 
level in the case, not only of iron but of magnesium, 
