GENERAL INTRODUCTION
9
involving as it doesthe many branches of knowledge that
_
pertain to a study of the life and conditions of the environ—
ment in the oceans and seas.
The study «of the ocean
currents, the tides, the,temperatures, and the saltness and
other chemical properties, is. approached through pure
physics and chemistry. The charting of the Ocean margins
and the mapping of the relief of the ocean beds are matters
for physical geographers.
Intimately bound up with ”the
great ocean »currents and the tides are meteorological and
'
astronomical phenomena.
The above studies constitùte
,
hydrography, although this term is more usually applied °
to the survey and charting of those features only which have
'
a_direct bearing upon navigation.
There remains the study
'
of the life in the sea, marine biology, which involves zoology,
botany, bacteriology, and includes the study of animal and
plant development, the study of the abundance of life, and
many other problems; to th ese must be added the application
to the shing industry of all knowledge of life and conditions
of life in the sea, shery research.
This composite whole
makes up the science of oceanography, which can“‘be summed
up as the study -of the‘world beneath the surface of the sea.
lt is evident, therefore, that up to 1522 when“ Magellan
sailed into the Pacic ocean the true science of ocean—
_
ography had not begun ; all these exploratory voyages had
but touched the marginbf the geographical side.
It,is'
true that Magellan made a sounding in the Pacic ocean,
but somewhat naïvely he argued that because he could not
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_
‘
touch bottom he had reached the deepest part of the ocean.
_
Soundings are recorded also in ancient times, butas yet—'there'
was 'no systematic attempt to map in'relief the ocean bed ;' \
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in fact it is doubtful whether, oWing to the backward state
of other sciences, it would then have been possible." It is * '
only.within the last few years that _it has been made
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by the introduction of echo sounding.
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,