human eye saw it
until 1896, when it was rediscovered at the Lick Observatory. Since
then the distance has gradually increased to nearly 5". According to
Burnham, its periodic time is about fifty-three years, and its nearest
approach to Sirius should have taken place in the middle of 1892. Later
calculations reduce the periodic time to forty-eight or forty-nine
years. If we can not see the companion of the Dog Star with our
instruments, we can at least, while admiring the splendor of that
dazzling orb, reflect with profit upon the fact that although the
companion is ten thousand times less bright than Sirius, it is half as
massive as its brilliant neighbor. Imagine a subluminous body half as
ponderous as the sun to be set revolving round it somewhere between
Uranus and Neptune. Remember that that body would possess one hundred
and sixty-five thousand times the gravitating energy of the earth, and
that five hundred and twenty Jupiters would be required to equal its
power of attraction, and then consider the consequences to our
easy-going planets! Plainly the solar system is not cut according to the
Sirian fashion. We shall hardly find a more remarkable coupling of
celestial bodies until we come, on another evening, to a star that
began, ages ago, to amaze the thoughtful and inspire the superstitious
with dread--the wonderful Algol in Perseus.

We may remark in passing that Sirius is the brightest representative of
the great spectroscopic type I, which includes more than half of all the
stars yet studied, and which is characterized by a white or bluish-white
color, and a spectrum possessing few or at best faint metallic lines,
but remarkably broad, black, and intense lines of hydrogen. The
inference is that Sirius is surrounded by an enormous atmosphere of
hydrogen, and that the intensity of its radiation is greater, surface
for surface, than that of the sun. There is historical evidence to
support the assertion, improbable in itself, that Sirius, within
eighteen hundred years, has changed color from red to white.

With either of our telescopes we shall have a feast for the eye when we
turn the glass upon the star cluster No. 1454, some four degrees south
of Sirius. Look for a red star near the center. Observe the curving rows
so suggestive of design, or rather of the process by which this cluster
was evolved out of a pre-existing nebula. You will recall the winding
streams in the Great Nebula of Orion. Another star clu