stars
appear to flow from the circumference of some; and, in other instances,
fantastic appendages of stars project outwards from the parent cluster.
There doubtless exists much variety in the structural arrangement of
these clusters, and an equal diversity in the magnitude and number of
the stars which enter into their formation. The stars in some clusters
may equal those of the first magnitude, and in others they may not
exceed in dimensions the minor planets. In the telescope they vary in
size from the eleventh to the fifteenth magnitude; the smaller stars
occupy the centre of a cluster, whilst the larger ones are found near
its circumference. Globular clusters are more condensed towards their
centre than those of irregular shape, and some have a nucleated
appearance. This apparent condensation is not altogether owing to the
depth of star strata as viewed from the circumference of the cluster,
but there appears to exist an attractive force (probably gravitational)
which draws the stars towards its centre, and if this 'clustering power'
were not opposed by some other counteracting force, those bodies would
coalesce into one mass. It may be 'that a centrifugal impulse
predominates by which full-grown orbs are driven from the nursery of
suns in which they were reared to seek their separate fortunes and enter
on an independent career elsewhere.'

It is not known how the dynamical equilibrium of a star cluster is
maintained; and on account of its extreme distance no motion is
perceptible among its component stars. The laws by which those stellar
aggregations are produced and governed are wrapped in obscurity, and the
nature of the motions of their stars, whether towards concentration or
diffusion, cannot at present be ascertained. If those globular clusters
could be observed sufficiently near, they would most probably expand
into vast systems of suns occupying immense regions of space.

The largest and most magnificent globular cluster in the heavens is
Omega Centauri, in the Southern Hemisphere. To the naked eye it
resembles a round, indistinct, cometary object, about equal to a star of
the fourth magnitude; but when observed with a powerful telescope it
appears as a globe of considerable dimensions composed of innumerable
stars of the thirteenth and fifteenth magnitudes, all exceedingly minute
and gathered into small knots and groups. A remarkable cluster in
Toucani is described by Sir John Herschel as 'most magnificen