, keeping a watch, after it had
vanished, upon the place where it had appeared, saw it again come into
view nine months after its disappearance. Since then it has been known
as a variable star with a period of about 331 days 8 hours. When
brightest this star is of the second magnitude. It indicates a somewhat
singular remissness on the part of the astronomers of former days, that
a star shining so conspicuously for a fortnight, once in each period of
331-1/3 days, should for so many years have remained undetected. It
may, perhaps, be thought that, noting this, I should withdraw the
objection raised above against Sir J. Herschel's idea that the star in
Cassiopeia may return to view once in 156 years, instead of once in 312
years. But there is a great difference between a star which at its
brightest shines only as a second-magnitude star, so that it has twenty
or thirty companions of equal or greater lustre above the horizon along
with it, and a star which surpasses three-fold the splendid Sirius. We
have seen that even in Tycho Brahe's day, when probably the stars were
not nearly so well known by the community at large, the new star in
Cassiopeia had not shone an hour before the country people were gazing
at it with wonder. Besides, Cassiopeia and the Whale are constellations
very different in position. The familiar stars of Cassiopeia are visible
on every clear night, for they never set. The stars of the Whale, at
least of the part to which the wonderful variable star belongs, are
below the horizon during rather more than half the twenty-four hours;
and a new star there would only be noticed, probably (unless of
exceeding splendour), if it chanced to appear during that part of the
year when the Whale is high above the horizon between eventide and
midnight, or in the autumn and early winter.

It is a noteworthy circumstance about the variable star in the Whale,
deservedly called Mira, or The Wonderful, that it does not always return
to the same degree of brightness. Sometimes it has been a very bright
second-magnitude star when at its brightest, at others it has barely
exceeded the third magnitude. Hevelius relates that during the four
years between October 1672 and December 1676, Mira did not show herself
at all! As this star fades out, it changes in colour from white to red.

Towards the end of September 1604, a new star made its appearance in
the constellation Ophiuchus, or the Serpent-Bearer. Its place was near
the