es Observatory.[1408] Their
genuineness was shortly afterwards visually attested by Keeler,
Campbell, and Duner;[1409] but no chemical interpretation has been found
for them.

A fairly complete preliminary answer to the question, What are the stars
made of? was given by Sir William Huggins in 1864.[1410] By laborious
processes of comparison between stellar dark lines and the bright rays
emitted by terrestrial substances, he sought to assure his conclusions,
regardless of cost in time and pains. He averred, indeed, that--taking
into account restrictions by weather and position--the thorough
investigation of a _single_ star-spectrum would be the work of some
years. Of two, however--those of Betelgeux and Aldebaran--he was able to
furnish detailed and accurate drawings. The dusky flutings in the
prismatic light of the first of these stars have not been identified
with the absorption of any particular substance; but associated with
them are metallic lines, of which 78 were measured, and a good many
identified by Huggins, while the wave-lengths of 97 were determined by
Vogel in 1871.[1411] A photographic research, made by Keeler at the
Alleghany Observatory in 1897, convinced him that the linear spectrum of
third-type stars of the Betelgeux pattern essentially repeats that of
the sun, but with marked differences in the comparative strength of its
components.[1412] Hydrogen rays are inconspicuously present. That an
exalted temperature reigns, at least in the lower strata of the
atmosphere, is certified by the vaporisation there of matter so
refractory to heat as iron.[1413]

Nine elements--among them iron, sodium, calcium, and magnesium--were
recognised by Huggins as having stamped their signature on the spectrum
of Aldebaran; while the existence in Sirius, and nearly all the other
stars inspected, of hydrogen, together with sundry metals, was rendered
certain or highly probable. This was admitted to be a bare gleaning of
results; nor is there reason to suppose any of his congeners inferior to
our sun in complexity of constitution. Definite knowledge on the
subject, however, made little advance beyond the point to which it was
brought by Huggins's early experiments until spectroscopic photography
became thoroughly effective as a means of research.

In this, as in so many other directions, Sir William Huggins acted as
pioneer. In March, 1863, he obtained microscopic prints of the spectra
of Sirius and Capella.[1414] But the