eighbourhood) is least in the pole of the Galactic circle [_i.e._, the
great circle to which the course of the Milky Way most nearly conforms:
_gala_ = milk], and increases on all sides down to the Milky Way itself,
where it attains its maximum. The progressive rate of increase in
proceeding from the pole is at first slow, but becomes more and more
rapid as we approach the plane of that circle, according to a law from
which it appears that the mean density of the stars in the galactic
circle exceeds, in a ratio of very nearly 30 to 1, that in its pole, and
in a proportion of more than 4 to 1 that in a direction 15 degrees
inclined to its plane.

As we ascend from the galactic plane we perceive that the density
decreases with great rapidity. So far we can perceive no flaw in this
reasoning if only it be granted (1) that the level planes are continuous
and of equal density throughout; and (2) that an absolute and definite
limit is set to telescopic vision, beyond which, if stars exist, they
elude our sight, and are to us as if they existed not. It would appear
that, with an almost exactly similar law of apparent density in the two
hemispheres, the southern were somewhat richer in stars than the
northern, which may arise from our situation not being precisely in the
middle of its thickness, but somewhat nearer to its northern surface.

_II.--Penetrating Infinite Space_

When examined with powerful telescopes, the constitution of this
wonderful zone is found to be no less various than its aspect to the
naked eye is irregular. In some regions the stars of which it is
composed are scattered with remarkable uniformity over immense tracts,
while in others the irregularity of their distribution is quite as
striking, exhibiting a rapid succession of closely clustering rich
patches separated by comparatively poor intervals, and indeed in some
instances absolutely dark and _completely_ void of any star even of the
smallest telescopic magnitude. In some places not more than 40 or 50
stars on an average occur in a "gauge" field of 15 minutes, while in
others a similar average gives a result of 400 or 500.

Nor is less variety observable in the character of its different
regions in respect of the magnitude of the stars they exhibit, and the
proportional numbers of the larger and smaller magnitudes associated
together, than in respect of their aggregate numbers. In some, for
instance, extremely minute stars, though never altogethe