rth in its orbit. In
nearly a hundred cases, however, small parallaxes have been determined,
some certainly (that is, within moderate limits of error), others more
or less precariously. The list is an instructive one, in its omissions
no less than in its contents. It includes stars of many degrees of
brightness, from Sirius down to a nameless telescopic star in the Great
Bear;[77] yet the vicinity to the earth of this minute object is so much
greater than that of the brilliant Vega, that the latter transported to
its place would increase in lustre thirty-eight times. Moreover, many of
the brightest stars are found to have no sensible parallax, while the
majority of those ascertained to be nearest to the earth are of fifth,
sixth, even ninth magnitudes. The obvious conclusions follow that the
range of variety in the sidereal system is enormously greater than had
been supposed, and that estimates of distance based upon apparent
magnitude must be wholly futile. Thus, the splendid Canopus, Betelgeux,
and Rigel can be inferred, from their indefinite remoteness, to exceed
our sun thousands of times in size and lustre; while many inconspicuous
objects, which prove to be in our relative vicinity, must be notably his
inferiors. The limits of real stellar magnitude are then set very widely
apart. At the same time, the so-called "optical" and "geometrical"
methods of relatively estimating star-distances are both seen to have a
foundation of fact, although so disguised by complicated relations as to
be of very doubtful individual application. On the whole, the chances
are in favour of the superior vicinity of a bright star over a faint
one; and, on the whole, the stars in swiftest _apparent_ motion are
amongst those whose _actual_ remoteness is least. Indeed, there is no
escape from either conclusion, unless on the supposition of special
arrangements in themselves highly improbable, and, we may confidently
say, non-existent.

The distances even of the few stars found to have measurable parallaxes
are on a scale entirely beyond the powers of the human mind to conceive.
In the attempt both to realize them distinctly, and to express them
conveniently, a new unit of length, itself of bewildering magnitude, has
originated. This is what we may call the _light-journey_ of one year.
The subtle vibrations of the ether, propagated on all sides from the
surface of luminous bodies, travel at the rate of 186,300 miles a
second, or (in round num