460 Proceedings of the Boyal Society 
had anything in this country equivalent to the Fortschrilte dev 
Physik, hut published with considerably less delay. 
Detailed study of Solar Spectrum — mainly due to the labours of 
two men. 
Maps by Kirchhoff and Angstrom, with the number of ele- 
ments proved to exist in the sun’s atmosphere. 
According to Angstrom, the following numbers of bright lines given by 
elements are found exactly coincident with dark lines in the solar 
spectrum : — 
Hydrogen, 
4 
Manganese, 
57 
Sodium, 
9 
Chromium, 
18 
Barium, 
11 
Cobalt, 
19 
Calcium , 
75 
Nickel, 
33 
Magnesium, 
4 + (3 ?) 
Zinc, 
m 
Aluminium, 
2(?) 
Copper, 
7 
Iron, 
450 
Titanium, 
118 
He notes that Thalen has found 200 coincidences with Titanium lines. 
Types of Stars — Secchi. 
I. White stars — Scarcely any absorption lines, except those due to 
Hydrogen, which are strongly marked. Sirius, Yega, &c. 
II. Yellow stars — The Sun, Arcturus, Aldebaran, &c. — multitudes of 
fine lines. 
III. Nebulous bands in addition to the fine lines — « Herculis, « Orionis, 
&c. In Mira Ceti these bands vary with the apparent magnitude. 
Similar appearances are observed in the spectra of sun-spots. On the 
contrary, Algol retains the first type through all its periodic changes. 
IV. Feeble spectrum crossed by bright lines. The stars of this type are 
all of small apparent magnitude ( i.e . of feeble luminosity), and 
usually of a blood-red colour. Temporary Stars — bright lines of 
hydrogen. 
If to these be added 
Y. Resolvable Nebulae — Continuous spectrum, as are those of the 
nebula in Andromeda* and of many others not resolvable ; and 
YI. Planetary Nebulae, and others irresolvable, such as those of Orion, 
Lyra, &c., where the spectrum consists of a very few bright lines 
only. 
it seems to me that we have a series of indications of what (for want of a 
better phrase) may be called the period of life of a star or group ; beginning 
with the glowing gases developed by the impacts of the agglomerating 
cold masses (YI.), * then the almost perfect spectrum of white-hot liquid or 
compressed gas (V., I.), which (as it becomes colder) suffers absorption by the 
rise of still colder vapours (II.) ; then, as it farther cools, nebulous bands 
take the place of sharp lines (III.) ; anon the bursts of glowing gases are 
* See the Abstract of my paper on Comets, Froc. R.S.E., 1868-9. 
