osely similar to that of sunlight, in being ruled
throughout by innumerable fine dark lines; and they share its yellowish
tinge.

The third class includes most red and variable stars (commonly
synonymous), of which Betelgeux in the shoulder of Orion, and "Mira" in
the Whale, are noted examples. Their characteristic spectrum is of the
"fluted" description. It shows like a strongly illuminated range of
seven or eight variously tinted columns seen in perspective, the light
falling from the red end towards the violet. This _kind_ of absorption
is produced by the vapours of metalloids or of compound substances.

To the fourth order of stars belongs also a colonnaded spectrum, but
_reversed_; the light is thrown the other way. The three broad zones of
absorption which interrupt it are sharp towards the red, insensibly
gradated towards the violet end. The individuals composing Class IV. are
few and apparently insignificant, the brightest of them not exceeding
the fifth magnitude. They are commonly distinguished by a deep red tint,
and gleam like rubies in the field of the telescope. Father Secchi, who
in 1867 detected the peculiarity of their analyzed light, ascribed it to
the presence of carbon in some form in their atmospheres; and this was
confirmed by the researches of H. C. Vogel,[1370] director of the
Astro-physical Observatory at Potsdam. The hydro-carbon bands, in fact,
seen bright in comets, are dark in these singular objects--the only ones
in the heavens (save one bright-line star and a rare meteor)[1371] which
display a cometary analogy of the fundamental sort revealed by the
spectroscope.

The members of all four orders are, however, emphatically suns. They
possess, it would appear, photospheres radiating all kinds of light, and
differ from each other mainly in the varying qualities of their
absorptive atmospheres. The principle that the colours of stars depend,
not on the intrinsic nature of their light, but on the kinds of vapours
surrounding them, and stopping out certain portions of that light, was
laid down by Huggins in 1864.[1372] The phenomena of double stars seem
to indicate a connection between the state of the investing atmospheres,
by the action of which their often brilliantly contrasted tints are
produced, and their mutual physical relations. A tabular statement put
forward by Professor Holden in June, 1880,[1373] made it, at any rate,
clear that inequality of magnitude between the components of bin