tars in Ursa Major, and those in Cassiopeia and Aquila are
familiarly known to all observers. Besides these, there are many other
groups and aggregations of stars which adorn the celestial vault and
enhance the beauty of the heavens.

STAR CLUSTERS.--On observing the heavens on a clear, dark night, there
can be seen in different parts of the sky closely aggregated groups of
stars called clusters. In some instances the component stars are so near
together that the naked eye is unable to discern the individual members
of the cluster. They then assume an indistinct, hazy, cloudlike
appearance. Upwards of 500 clusters are known to astronomers, the
majority of which are very remote. Many of them contain thousands of
stars compressed into a very small space, and others are so distant that
the largest telescopes are incapable of resolving their nebulous
appearance into separate stars.

Star clusters have been arranged into two classes, 'irregular' and
'globular;' but no sharp line of demarcation exists between them, though
each have their distinctive peculiarities. Irregular clusters consist of
aggregations of stars brought promiscuously together, and presenting an
appearance devoid of any structural arrangement. They are of different
shapes and sizes, possess no distinct outline, and are not condensed
towards their centre, like those that are globular. On examination, they
present an intricate reticulated appearance; streams and branches of
stars extend outwards from the parent cluster, sometimes in rows and
sinuous lines, and, in other instances, diverging from a common centre,
forming sprays. Sometimes the stars are seen to follow each other on the
same curve which terminates in loops and arches of symmetrical
proportions.

There are three conspicuous clusters in the northern sky that are
visible to the naked eye--viz. the Pleiades in Taurus, the Great Cluster
in the sword-handle of Perseus, and Praesepe in Cancer, commonly called
the Beehive.

The cluster which from time immemorial has had bestowed upon it the
chief attention of mankind are the beautiful Pleiades or Seven Sisters,
and intertwined among its stars are the legendary and mythological
beliefs of ancient nations and untutored tribes inhabiting the different
regions of the globe. When viewed with a telescope of moderate size the
cluster appears as a scattered group, and numerous stars become visible
that are imperceptible to ordinary vision.

In the sword-h