144 REPORT—1868. 
The upper one represents the spectrum of Aldebaran, and the other that 
of Betelgeux, the star marked a in the constellation of Orion. 
The positions of all these dark lines, about eighty in each star, were 
determined by careful and repeated measures. These measured lines form 
but a small part of the numerous fine lines which may be seen in the spectra 
of these stars. 
Beneath the spectrum of each star are arranged the bright lines of the 
metals which have been compared with it. These terrestrial spectra appeared 
in the instrument, as they are represented in the diagram, in juwtaposition 
with the spectrum of the star. By such an arrangement it is possible to 
determine with great accuracy whether or not any of these bright lines 
actually coincide with ¢ any of the dark ones. 
The results on these stars are given in the following Table :— 
ELEMENTS COMPARED WITH ELEMENTS COMPARED WITH 
ALDEBARAN. BEreLeEevx. 
Coincident. Coincident. 
1, Hydrogen with lines C and F. 1. Sodium with double line D. 
2. Sodium with double line D. 2. Magnesium with triple line 0. 
3. Magnesium with triple line 0. 3. Calcium with four lines. 
4. Calcium with four lines. 4. Iron with three lines and E. 
5. Iron with four lines and E. 5. Bismuth with four lines. 
6. Bismuth with four lines. 6. Thallium (?). 
7. Tellurium with four lines. 
8. Antimony with three lines. Not coincident. 
9. Mercury with four lines. Hydrogen compared with C and F. 
sade Nitrogen F », three lines. 
Not coincident. Tin cs ” five lines. 
Nitrogen compared with three lines. Lead ¥, », two lines. 
Cobalt a 5, two lines. Gold (?). 
Tin : », five lines. Cadmium aj », three lines. 
Lead - » two lines. Silver + », two lines. 
Cadmium ,, ,, three lines. Mercury a », four lines. 
Barium “a » two lines. Barium Pe », two lines. 
Lithium om 5, one line, Lithium Pi » one line. 
Now, in reference to all these elements, the evidence does not rest upon 
the coincidence of one line, which would be worth but little, but upon the 
coincidence of a group of two, three, or four lines, occurring in different 
parts of the spectrum. Other corresponding lines are probably also present, 
but the faintness of the star’s light limited the comparisons to the stronger 
lines of each element. 
What elements do the numerous other lines in the star represent? Some 
of them are probably due to the vapours of other terrestrial elements which 
we have not yet compared with these stars. But may not some of these 
lines be the signs of primary forms of matter unknown upon the earth? 
Elements new to us may here show themselves, which form large and 
important series of compounds, and therefore give a special character to the 
physical conditions of these remote systems. In a similar manner the spectra 
of terrestrial substances have been compared with several other stars. 
B Pegasi contains sodium, magnesium, and perhaps barium. 
Sirius contains sodium, magnesium, iron, and hydrogen. 
a Lyre (Vega) contains sodium, magnesium, iron. 
Pollux contains sodium, magnesium, iron. 
About sixty other stars have been examined, all of which appear to have 
some elements in common with the sun and earth, but the selective grouping 
of the elements in each star is probably peculiar and unique. 
