Fuly 1, 1886] 
area, which, let us say, is a couple of hundred times greater, 
in that case we shall be bound to have bright lines from 
the exterior regions mixing with the dark lines coming from 
the interior regions. Hence we see that the spectra which 
we may get from stars will not depend upon the diameter of the 
stars at all, but may depend upon the difference of area simply 
which we should get by cutting a section at right angles to the 
line of sight from the earth through the star and its whole 
atmosphere. 
It comes to this : Suppose some stars have very large coronal 
atmospheres ; if the area of the coronal atmosphere is small 
compared with the area of the section of the true disk of the sun, 
of course we shall get an ordinary spectrum of the star; that is 
to say, we shall get the indications of absorption which 
make us class the stars apart; we shall get a continuous 
spectrum barred by dark lines. But suppose that the area of 
the coronal atmosphere is something very considerable indeed, 
let us assume that it has an area, say fifty times greater than the 
section of the kernel of the star itself ; now, although each unit 
of surface of that coronal atmosphere may be much less luminous 
than an equal unit of surface of the true star at the centre, yet if 
the area be very large, the spectroscopic writing of that large 
area will become visible side by side with the dark lines due to 
the brilliant region in the centre where we can study absorption ; 
other lines (bright ones) proceeding from the exterior portion of that 
fod HERCULIS 
[2 PECASI 
‘i 
b 
0 ORIONIS. a 
NATURE 207 
star will be visible in the spectrum of the apparent foén¢ we call 
a star.} 
Those things, then, being premised, we are now in a position 
to approach the subject of stellar spectra. Much work is now 
being done in this direction, but we must not forget the early 
workers. We must not forget that it was Fraunhofer at the 
beginning of this century who first saw and carefully observed 
several spectra of stars, and we must be all the more careful to 
remember that, since really more than half a century passed 
before anybody took the trouble either to repeat his observations 
or to extend them. Some twenty years ago, however, several 
observations had been brought together by the labours of Italian 
and American men of science (scarcely a stellar spectrum had 
been observed in England). This enabled a distinguished 
American, Mr. Rutherfurd, to begin to put a little order into the 
facts which had so far been acquired. 
He pointed out that it was easy to arrange these stars ito 
classes—that all the spectra were not alike. There was a won- 
derful family likeness among three groups of them, and he 
showed that you might divide these spectra into three very 
definite classes. After him came two countrymen of our own, Dr. 
Huggins and Dr. Miller, who, when they did begin their work, 
certainly put into it an amount of vigour and assiduity which 
had never been approached before their time. They not only 
gave us careful drawings of the spectra of the stars which they 
Fic. 21.—Various types of stellar spectra 
observed, but with infinite care and patience they made com- 
parisons, as we may say, to determine the origin of the lines in 
exactly the same way as I have pointed out that Kirchhoff, 
ngstro u, and Thalén discovered the origin of the lines in the 
spectrum of the sun. Indeed, they did not rest here, or rather, 
one of them did not rest here, for Dr. Huggins subsequently 
introduced a system of photography, and now, thanks to his 
skill, we have several photographs, of priceless value, of some 
of the brighter stars. And while I am lecturing to you here 
in London there is one observer in Berlin, Dr. Vogel, and 
another in the north of Europe, Dr. Dunop, doing all they can 
to give us a complete and perfect spectroscopic catalogue of 
every star that shines in the northern heavens, so that you can 
see that the work is going on. 
Now, before I say any more about it, I will refer to a diagram 
which gives an idea of the kind of thing that one sees when 
these observations are being made. 
We will just run through them one by one. There is a very 
rough and general view of the spectrum of the sun. The actual 
spectrum of the sun has been thrown on the screen before you, 
and therefore it will be quite understood that there we have a 
very rough copy of it for diagrammatic purposes, indicating merely 
the most obvious among the Fraunhofer lines. When we pass 
from the sun to a Lyra, we pass from a star having a relatively 
large number of lines to one having a small number; and this 
small number of lines is further remarkable from the fact that 
the lines are much thicker than those seen ordinarily in the solar 
spectrum. Keeping to the stars which give us spectra of lines, 
here in a Orionis we get another case in which the lines do not 
occupy the places occupied by lines in the spectrum of the sun, 
nor, at the same time, are they so thick as the lines in stars of 
the Lyra type. We can also learn from this diagram, by the 
examination of the spectra of a Herculis and 8 Pegasi, that we 
get flutings from stars as well as lined spectra. We also see that 
these flutings are not all exactly in the same place, by which we: 
can infer that the flutings are not all probably of the same chemical: 
origin. Of that further by and by. The use of the diagram is. 
to give a general idea. |. NorMAN LOCKYER 
(To be continued.) 
SCIENTIFIC SERIALS 
The American Fournal of Science, June.—The Biela meteors: 
of November 27, 1885, by H. A. Newton. From a general 
survey of the observations made in various places, the author 
infers that the maximum of the shower was about 6h. 15m. 
Greenwich mean time ; that the total hourly number of meteors 
visible at one place in a clear sky was at the utmost 
75,000; that the densest part of the stream was not over 
100,coo miles in thickness ; that the meteors of November 27, 
t Proc. Roy. Soc , No. 185, 1878 
