But
the most accurate counts of stars that have been made fail to show
any difference in their general arrangement in the two
hemispheres. They are just as thick around the south galactic
poles as around the north one. They show the same tendency to
crowd towards the Milky Way in the hemisphere invisible to us as
in the hemisphere which we see. Slight differences and
irregularities, are, indeed, found in the enumeration, but they
are no greater than must necessarily arise from the difficulty of
stopping our count at a perfectly fixed magnitude. The aim of
star-counts is not to estimate the total number of stars, for this
is beyond our power, but the number visible with a given
telescope. In such work different observers have explored
different parts of the sky, and in a count of the same region by
two observers we shall find that, although they attempt to stop at
the same magnitude, each will include a great number of stars
which the other omits. There is, therefore, room for considerable
difference in the numbers of stars recorded, without there being
any actual inequality between the two hemispheres.
A corresponding similarity is found in the physical constitution
of the stars as brought out by the spectroscope.
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