x of alpha Centauri, a fine double star of the Southern
Hemisphere, at present considered to be the nearest of the fixed stars,
was first determined by Henderson and Maclear at the Cape of Good Hope
in 1832-'33. It is about nine-tenths of a second. Hence this star is
almost two hundred and thirty thousand times as far from us as the sun.
Seen from it, if the sun were even large enough to fill the whole orbit
of the earth, or one hundred and eighty million miles in diameter,
he would be a mere point. With its companion, it revolves round their
common centre of gravity in eighty-one years, and hence it would seem
that their conjoint mass is less than that of the sun.

The star 61 Cygni is of the sixth magnitude. Its parallax was first
found by Bessel in 1838, and is about one-third of a second. The
distance from us is, therefore, much more than five hundred thousand
times that of the sun. With its companion, it revolves round their
common centre of gravity in five hundred and twenty years. Their
conjoint weight is about one-third that of the sun.

There is reason to believe that the great star Sirius, the brightest
in the heavens, is about six times as far off as alpha Centauri. His
probable diameter is twelve million miles, and the light he emits two
hundred times more brilliant than that of the sun. Yet, even through the
telescope, he has no measurable diameter; he looks merely like a very
bright spark.

The stars, then, differ not merely in visible magnitude, but also in
actual size. As the spectroscope shows, they differ greatly in chemical
and physical constitution. That instrument is also revealing to us the
duration of the life of a star, through changes in the refrangibility of
the emitted light. Though, as we have seen, the nearest to us is at
an enormous and all but immeasurable distance, this is but the first
step--there are others the rays of which have taken thousands, perhaps
millions, of years to reach us! The limits of our own system are far
beyond the range of our greatest telescopes; what, then, shall we say of
other systems beyond? Worlds are scattered like dust in the abysses in
space.

Have these gigantic bodies--myriads of which are placed at so vast a
distance that our unassisted eyes cannot perceive them--have these no
other purpose than that assigned by theologians, to give light to us?
Does not their enormous size demonstrate that, as they are centres of
force, so they must be centres of moti