428 
ME. W. HUGGINS AND DE. W. A. MILLEE ON 
(3) Hydrogen. — Both the lines corresponding to F and C have intensely strong lines 
in the star-spectrum. 
(4) Iron. — No direct comparison with this metal was made ; hut the cross wires having 
been set to a position corresponding with E of the solar spectrum, a faint line in the 
star was seen exactly to bisect the wires when the telescope was turned upon Sirius. 
The whole spectrum of Sirius is crossed by a very large number of faint and fine 
lines. 
It is worthy of notice that in the case of Sirius, and a large number of the white stars, 
at the same time that the hydrogen lines are abnormally strong as compared with the 
solar spectrum, all the metallic lines are remarkably faint. 
On the 27th February, 1863, and on the 3rd of March of the same year, when the 
spectrum of this star was caused to fall upon a sensitive collodion surface, an intense 
spectrum of the more refrangible part was obtained. From want of accurate adjust- 
ment of the focus, or from the motion of the star not being exactly compensated by the 
clock movement, or from atmospheric tremors, the spectrum, though tolerably defined 
at the edges, presented no indications of lines. Our other investigations have hitherto 
prevented us from continuing these experiments further but we have not abandoned 
our intention of pursuing them. 
15. a Lye^e (Vega). — This is a white star having a spectrum of the same class as 
Sirius, and as full of fine lines as the solar spectrum. Many of these we have measured, 
but our investigation of this star is incomplete. 
We have ascertained the existence, in the stellar spectrum, of a double line at D 
corresponding to the lines of sodium , of a triple line at b coinciding with the group of 
magnesium , and of two strong lines coincident with the lines of hydrogen C and F. 
16. Capella. — This is a white star with a spectrum closely resembling that of our 
sun. The lines are very numerous ; we have measured more than twenty of them, 
and ascertained the existence of the double sodium line at D,but we defer giving details 
until we have completed our comparison with the spectra of other metals. 
From this star we obtained (on February 27, 1863) a photograph of the more refran- 
gible end of the spectrum ; but the apparatus was not sufficiently perfect to exhibit any 
stellar lines. 
17. Aectueus (aBootis). — This is a red star the spectrum of which somewhat resem- 
bles that of the sun. In this also we have measured upwards of thirty lines, and have 
ascertained the existence of a double sodium line at D ; but our comparisons with other 
metallic spectra are not yet complete. 
18. Pollux. — In the spectrum of this star, which is rich in lines, we have measured 
twelve or fourteen, and have observed coincidences with the lines of sodium , magnesium, 
and probably of iron. At any rate there is a line which we believe occupies the posi- 
tion of E in the solar spectrum. 
a Cygni and Procyon are both full of fine lines. In each of these spectra we observed 
a double line coincident with the sodium D. 
