262 
NATURE 
[Fed. 2, 1871 


some of its angular prolongations, more upon the observa- 
tions of 1869, when the sky was exceptionally clear, than 
upon anything seen at this time; and yet all the obser- 
vations of this year, so far as I can see, accord well 
enough with the idea. 
The two faint lines which I saw last year between D 
and 1474, and which I thought might also be corona | 
lines, were not seen this year by any one, so far as I can 
learn, 
not then at all positive about their belonging to the corona 
(I have felt somewhat annoyed by finding them put on 
the same footing as 1474 in several publications of the 
last year or two), and my present impression is that they 
were two of the faint iron lines that often appear in 
protuberances in that portion of the spectrum. 
The question has been raised whether the corona line 
exactly coincides with the 1474 dark line in the solar 
spectrum. The difference, if any (and I have not found 
the sligktest reason to suspect the least want of coincidence 
in observations with the whole dispersive power of 13 
prisms), is less than ,', of one division of Kirchhoff’s scale, 
Just before the totality began, 1 placed the slit of my 
spectroscope exactly tangential to the sun’s limb at the 
point which would be last covered, and brought the 1474 
line, already bright, as is usually the case at the base of | 
the chromosphere, exactly to the cross hairs. After the 
totality had fairly begun, I moved the equatorial in right 
ascension until the slit was more than 16’ east of the 
sun’s limb, and the line remained continually visible, 
though of course growing fainter as the distance from 
the sun increased. There is not the slightest possibility 
of mistake, nor of error beyond the limit named, 2.z., 5 of 
one division of Kirchhoff’s scale. 
And now a few words in relation to the nature of the 
Corona. It seems to me to be a complex phenomenon, 
made up of at least four, perhaps five different elements ; 
and in the main I concur with the views put forth by Mr. 
Lockyer in a recent number of NATURE, with the excep- 
tion that I should be disposed to assign a greater relative 
importance to the truly solar portion of the phenomenon 
than he appears to do. 
1st. We have, I think, surrounding the sun, beyond any 
further reasonable doubt, a mass of selt-luminous gaseous 
matter, whose spectrum is characterised by the green 
1474 line. The precise extent of this it is hardly yet pos- 
sible to consider as determined, but it must be many times 
the thickness of the red hydrogen portion of the chromo- 
sphere : perhaps, on an average, 8’ or ro’, with occasional 
horns of twice that height. It is not at all unlikely that 
it may even turn outto have zo upper limit, but to ex'end 
from the sun indefinitely into space. 
2nd. This region undoubtedly reflects to us a cer- 
tain amount of the ordinary photospheric sunlight. 
This reflected light is of course polarised radially toa 
considerable extent. Its spectrum ought to show the 
ordinary dark Ines, but they are parily masked in the 
minner Mr. Lockyer has so happily explained, and partly 
by the faintness of the spectrum. 
3rd. Our own atmosphere, even when clearest, must 
apparently extend this corona, both outwards, and inwards 
upon the moon’s disc. Since, however, the inner edge of 
the coronal ring is far the brightest, the inward extension 
of the corona should be most marked, except at the very 
I certainly saw two such lines last year, but I was | 
| 
beginning or end of totality, and I have no doubt it is: 
that 1s to say, at the middle of totality the illumination 
of the moon's disc gives a somewhat exaggerated measure 
of the effect of our own atmosphere in extending the 
corona outwards. Accordingly, I am disposed to think 
the effect of the atmosphere (when clear) is a very 
subordinate one, since in 1869 the light upon the moon’s 
| disc was only very trifling compared with that evena 
whole degree from the sun. This atmospheric light would 
also be polarised radially. Its spectrum would be mainly 
that of the chromosphere, prominences, and “leucosphere” 
combined, a discontinuous bright line spectrum. 
4th. There must be a large subjective element, for two 
even skilled observers, standing side by side, describe 
phenomena differing in very essential points. 
5th. I am somewhat inclined to think with Oudemans 
(see his paper published in NATURE Nov. 10) that possibly 
cosmical dust between us and the moon may play an im- 
portant part. Assuming alight cloud of such matter, one 
or two hundred thousand miles above the earth’s surface 
and of great thickness, it becomes easy to account for the 
straight dark streaks, the varying form (if it does vary), and 
many other puzzling phenomena of the corona-phenomena 
which can hardly be produced by portions of our own 
atmosphere deeply immersed in the lunar shadow, but 
which, I own, seem to me now less aurora-like and less 
certainly solar than they did a yearago. I do not see 
how optical tests by polariscope and spectroscope could 
discriminate between the effects of such a cloud and those 
of our own atmosphere. C. A. YOUNG 


POPULAR NAMES OF BRITISH PLANTS 
The. Popular Names of British Plants. By R. C. A. 
Prior, M.D., F.L.S. Second Edition. (Williams and 
Norgate.) 
HERE are many botanists who know little of the 
English names of Plants ; and there are many who 
know these intimately, yet are not botanists. Bothclasses 
will welcome this comprehensive volume: and those who 
possess neither a philosophical nor a popular knowledge 
of the subject, will yet find abundant interest in a book, 
which is the work of an accurate scholar and philologist, 
as well as of a scientific botanist. 
Most interesting, and perhaps least expected, is the 
light which these names throw upon the history of early 
civilisation. Many of them date from a period antece- 
dent to the European settlement of the Aryan race, and 
enlighten us as to the habits of our remote ancestors 
some thousand years ago. We discover from them that 
the men who continuously advanced through many coun- 
tries, from the confines of India to the British Islands, 
were norace of savages, but a comparatively civilised 
community : that they understood letters ; that they had 
a knowledge of the useful metals ; that they possessed 
the principal domestic animals ; that they cultivated the 
oak, the beech, the birch, the hawthorn, the apple; grew 
wheat, barley, oats, rye, beans; built timber houses and 
thatched them; hedged their fields and fenced their 
gardens. 

In a later class of names, which betray the intercourse 
of our forefathers with Roman cultivation and Grecian 
| poetry, many a strange piece of myth or history lies em- 
