spectra may be made with a degree of accuracy not otherwise
obtainable; and, in case of the stars, whole clusters of spectra
may be placed on record at a single observation.

As the examination of the sun and stars proceeded, chemists were
amazed or delighted, according to their various preconceptions,
to witness the proof that many familiar terrestrial elements are
to be found in the celestial bodies. But what perhaps surprised
them most was to observe the enormous preponderance in the
sidereal bodies of the element hydrogen. Not only are there vast
quantities of this element in the sun's atmosphere, but some
other suns appeared to show hydrogen lines almost exclusively in
their spectra. Presently it appeared that the stars of which
this is true are those white stars, such as Sirius, which had
been conjectured to be the hottest; whereas stars that are only
red-hot, like our sun, show also the vapors of many other
elements, including iron and other metals.

In 1878 Professor J. Norman Lockyer, in a paper before the Royal
Society, called attention to the possible significance of this
series of observations. He urged that the fact of the sun showing
fewer elements than are observed here on the cool earth, while
stars much hotter than the sun show chiefly one element, and that
one hydrogen, the lightest of known elements, seemed to give
color to the possibility that our alleged elements are really
compounds, which at the temperature of the hottest stars may be
decomposed into hydrogen, the latter "element" itself being also
doubtless a compound, which might be resolved under yet more
trying conditions.