CHAPTER II 
THE GENERAL FEATURES OF THE EARTH 
The Earth a Planet. — The earth is a great spherical 
body with an equatorial diameter of about 7926 miles, 
and a circumference of nearly 25,000 miles. It is one 
of a family of bodies in space, which journey about a 
central member, the sun. These planets all rotate on 
axes and revolve about the sun, being kept in their 
places by the action of gravitation, which governs all 
bodies in the universe. 
Hach member of this solar family is exerting some 
influence on the earth; but two, the moon and the 
sun, are the most important in their effect; the moon 
because it is so near, and the sun because it is so large 
and hot. From the sun are obtained the heat and light 
which render possible the life on the earth; and by far 
the greater number of geological changes which are 
in progress upon the surface of the earth, are derived 
from solar energy. 
Condition of the Earth. — There are three parts to 
the earth —a solid portion, or the earth itself; a liquid 
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