The
learned hydrographer Fleurieu has very justly named this
p 289
vast oceanic basis, which, under the tropics, extends over 145??degrees of
longitude, the 'Great Ocean', in contradistinction to all other seas. The
southern and western hemispheres (reckoning the latter from the meridian of
Teneriffe) are therefore more rich in water than in any other region of the
whole earth.
These are the main points involved in the consideration of the relative
quantity of land and sea, a relation which exercises so important an
influence on the distribution of temperature, the variations in atmospheric
pressure, the direction of the winds, and the quantity of moisture contained
in the air, with which the development of vegetation is so essentially
connected. When we consider that nearly three fourths of the upper surface
of our planet are covered with water,* we shall be less surprised at the
imperfect condition of meteorology before the beginning of the present
century, since it is only during the subsequent period that numerous
accurate observations on the temperature of the sea at different latitudes
and at different seasons have been made and numerically compared together.
[footnote] *In the Middle Ages, the opinion prevailed that the sea covered
one seventh of the surface of the globe, an opinion which Cardinal d'Ailly
('Imago Mundi', cap.
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