GEOLOGY 
No study illustrates better than Geology not only the 
advantage but the absolute necessity of general knowledge 
for the thorough understanding of any particular subject. 
Geology means literally a discourse on the earth. The 
student of so vast a theme ought naturally therefore to be 
familiar with at least the general conclusions offered by 
Astronomers, Physicists, Chemists, Mineralogists, Botanists, 
and Zoologists, so far as they relate to the history of this 
planet, since by astronomical data we picture our earth as a 
once gaseous, chaotic mass. The study of the cooling of 
heated bodies under pressure, implying a knowledge of the 
laws of Heat and Chemistry, furnishes the clue to the ex- 
planation of the origin of many formations. Mineralogy 
distinguishes the different rocks of which the crust of the 
earth is composed, while Botany and Zoology supply the 
means by which the life of bygone days is revivified, 
enabling us to interpret the structure and relations of plants 
and animals long since extinct. Geology, therefore, is not 
a separate science, since it consists only of the conclusions 
of many sciences applied to the investigation of the past 
and present history of the earth. As three-fourths of the 
earth are covered with water, with our present resources 
only a very small portion is susceptible of geological ex- 
amination. And notwithstanding the great number of 
surveys and scientific expeditions which have been made 
during the present century, with the exception of Great 
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