tendency to a double maximum, and complexity of superposed
periods.[1466] It is impossible to compare the two sets of phenomena
thus graphically portrayed without reaching the conclusion that they are
of closely related origin. But the correspondence indicated is not, as
has often been hastily assumed, between maxima of sun-spots and minima
of stellar brightness, but just the reverse. The luminous outbursts, not
the obscurations of variable stars, obey a law analogous to that
governing the development of spots on the sun. Objects of the kind do
not, then, gain light through the closing-up of dusky chasms in their
photospheres, but by an actual increase of surface-brilliancy, together
with an immense growth of these brilliant formations--prominences and
faculae--which, in the sun, accompany, or are appended to spots. A
comparison of light-curves with curves of spot-frequency leaves no doubt
on this point, and the strongest corroborative evidence is derived from
the emergence of bright lines in the spectra of long-period variables
rising to their recurring maxima.

Every kind and degree of variability is exemplified in the heavens. At
the bottom of the scales are stars like the sun, of which the lustre
is--tried by our instrumental means--sensibly steady. At the other
extreme are ranged the astounding apparitions of "new," or "temporary"
stars. Within the last thirty-six years eleven of these stellar guests
(as the Chinese call them) have presented themselves, and we meet with a
twelfth no farther back than April 27, 1848. But of the "new star" in
Ophiuchus found by Mr. Hind on that night, little more could be learnt
than of the brilliant objects of the same kind observed by Tycho and
Kepler. The spectroscope had not then been invented. Let us hear what it
had to tell of later arrivals.

About thirty minutes before midnight of May 12, 1866, Mr. John
Birmingham of Millbrook, near Tuam, in Ireland, saw with astonishment a
bright star of the second magnitude unfamiliarly situated in the
constellation of the Northern Crown. Four hours earlier, Schmidt of
Athens had been surveying the same part of the heavens, and was able to
testify that it was not visible there. That is to say, a few hours, or
possibly a few minutes, sufficed to bring about a conflagration, the
news of which may have occupied hundreds of years in travelling to us
across space. The rays which were its messengers, admitted within the
slit of Sir William Hug