on particles which bear
the marks of having experienced a high temperature.

The earth draws in this cosmic dust continuously, but the earth now
never parts with a particle of its mass. The consequence is inevitable;
the mass of the earth must be growing, and though the change may be a
small one, yet to those who have studied Darwin's treatise on
"Earth-worms," or to those who are acquainted with the modern theory of
evolution, it will be manifest that stupendous results can be achieved
by slight causes which tend in one direction. It is quite probable that
an appreciable part of the solid substance of our globe may have been
derived from meteoric matter which descends in perennial showers upon
its surface.

CHAPTER XVIII.

THE STARRY HEAVENS.

The Constellations--The Great Bear and the Pointers--The Pole
Star--Cassiopeia--Andromeda, Pegasus, and Perseus--The Pleiades:
Auriga, Capella, Aldebaran--Taurus, Orion, Sirius; Castor and
Pollux--The Lion--Booetes, Corona, and Hercules--Virgo and
Spica--Vega and Lyra--The Swan.

The student of astronomy should make himself acquainted with the
principal constellations in the heavens. This is a pleasing acquirement,
and might well form a part of the education of every child in the
kingdom. We shall commence our discussion of the sidereal system with a
brief account of the principal constellations visible in the northern
hemisphere, and we accompany our description with such outline maps of
the stars as will enable the beginner to identify the chief features of
the starry heavens.

In an earlier chapter we directed the attention of the student to the
remarkable constellation of stars which is known to astronomers as Ursa
Major, or the Great Bear. It forms the most conspicuous group in the
northern skies, and in northern latitudes it never sets. At eleven p.m.
in the month of April the Great Bear is directly overhead (for an
observer in the United Kingdom); at the same hour in September it is low
down in the north; at the same hour July it is in the west; by Christmas
it is at the east. From the remotest antiquity this group of stars has
attracted attention. The stars in the Great Bear were comprised in a
great catalogue of stars, made two thousand years ago, which has been
handed down to us. From the positions of the stars given in this
catalogue it is possible to reconstruct the Great Bear as it appeared in
those early days. This has been d