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1. Geography is the scientific description of the earth, considered as the habitation of mankind. is closely related to astronomy, geology, natural history, political history, and statistics: hence it is usually distributed under three heads-astronomical, physical, and political. Astronomical geography treats of the figure, magnitude, and motions of the earth, together with her place in the solar system. Physical geography treats of the great natural phenomena of the earth's surface, together with the distribution of vegetables, animals, and mankind. Political geography treats of the civil and ecclesiastical condition, the resources, industry, and commerce of the various nations and people of the earth, at any given time, and chiefly as determined by natural





2. Figure of the Earth.-The general figure of the earth is that of a sphere or globe. This truth is proved by such arguments as the following: (1.) As a ship recedes from the shore, she diminishes in apparent size, yet the whole can be seen until she reaches the visible horizon. When she has passed this limit, the hull begins to disappear, and soon vanishes, although the masts and sails may yet be discerned; but these, too, seem gradually to sink into the water, and the whole at last disappears. Such appearances would not take place if the earth were a flat extended surface: but they are precisely such as would occur if the earth were globular; therefore they render it probable that this is her true figure. (2.) The earth has been circumnavigated, as by Magellan and Drake, who, sailing from Europe in a course always to the west, have arrived at the place whence they had departed, thus proving that the earth's surface is circular in that general direction. Observations on the stars, made by navigators towards the north, and towards the south, establish the truth of this conclusion as regards those directions. Such voyages and observations have been multiplied, and establish the general conclusion that the earth is a globe. (3.) When by a series of observations we have ascertained that the eclipses of the moon are caused by the conical shadow of the earth, which has invariably a circular boundary on the

moon's disc, we have obtained the fullest confirmation of the earth's rotundity, since the body, which, under all circumstances, casts such a shadow, must be globular.

3. While such arguments as these prove that the general figure of the earth is spherical, careful observation and calculation have determined that its exact figure is that of an oblate spheroid; but one which differs so little from a sphere, all whose diameters are equal, that the difference of the two extreme diameters of the spheroid would not, on a 12-inch globe, exceed the thickness of a leaf of common writingpaper.

4. The inequalities of the earth's surface furnish no argument against its general form, since the highest mountains bear a less ratio to the whole earth than a grain of sand to an ordinary artificial globe. The vulgar notions respecting up and down have given rise to untenable objections to the doctrine of the earth's sphericity. How, it is asked by untaught objectors, could our antipodes remain upon the earth if it were spherical; since their feet would be uppermost, their heads hanging down in the air? We reply, that all parts of the earth, all things and persons on its surface, are attracted towards the centre: and that the words up and down properly refer, not to the heavens, but to the earth's centre and surface; from the centre to the surface being up, from the surface to the centre down. Our antipodes are in the same position, relative to the earth, as ourselves : they have the surface of the earth beneath their feet, and the heavens above their heads.

5. Magnitude of the Earth.-The earth's equa

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