The same may be said of the brilliant Nova Persei, brighter at its
best than Capella, and discovered also by Dr. Anderson on February
22nd, 1901. It increased in brightness as it reached the densest part
of the nebula, then it varied for some weeks by a couple of
magnitudes, up and down, as if passing through separate nebular
condensations. In February, 1902, it could still be seen with an
opera-glass. As with the other Novae, when it first dashed into the
nebula it was vaporised and gave a continuous spectrum with dark lines
of hydrogen and helium. It showed no bright lines paired with the dark
ones to indicate a train left behind; but in the end its own
luminosity died out, and the nebular spectrum predominated.

The nebular illumination as seen in photographs, taken from August to
November, seemed to spread out slowly in a gradually increasing circle
at the rate of 90" in forty-eight days. Kapteyn put this down to the
velocity of light, the original outburst sending its illumination to
the nebulous gas and illuminating a spherical shell whose radius
increased at the velocity of light. This supposition seems correct, in
which case it can easily be shown from the above figures that the
distance of this Nova was 300 light years.

_Star Catalogues._--Since the days of very accurate observations
numerous star-catalogues have been produced by individuals or by
observatories. Bradley's monumental work may be said to head the list.
Lacaille's, in the Southern hemisphere, was complementary. Then
Piazzi, Lalande, Groombridge, and Bessel were followed by Argelander
with his 324,000 stars, Rumker's Paramatta catalogue of the southern
hemisphere, and the frequent catalogues of national observatories.
Later the Astronomische Gesellschaft started their great catalogue,
the combined work of many observatories. Other southern ones were