16 PHYSICAL GEOGRAPHY.

 

as at the equator, and consequently any portion
of the earth’s surface represented on such a chart,
if situated toward the poles, will be dispropor-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 10, The Earth on Mercator's Projection.

tionally large. In order to avoid the distortion
in the shape of the land and water areas, the dis-
tance between successive parallels is increased as

 

they approach the poles. The dimensions of the
land or water, however, are greatly exaggerated
in these regions. The immediate polar regions
are never represented on such charts, the poles
being supposed to be at an infinite distance.

Mercator’s charts are generally employed for physical
maps, on account of the facility they afford for showing
direction. The distortion they produce in the relative
size of land or water areas must be carefully borne in
mind, or wrong ideas of the relative size of various parts
of the world will be obtained.

Mercator’s charts make bodies of land and
water situated near the poles appear much larger
than they really are.

In an Equatorial Projection of the entire earth
the equator passes through the middle of each
hemisphere, and a meridian circle forms the
borders.

In a Polar Projection of the entire earth the

 

 

 

 

 

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poles occupy the centres of each hemisphere, and
the equator forms the borders.
In a Conical Projection the earth’s surface is

 

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Fig. 11, The Earth on an Equatorial Projection.

represented as if drawn on the frustum of a cone
and afterward unrolled. This projection is. suit-
able where only portions of the earth’s surface,

Fig. 12, The Earth on a Polar Projection.

and not hemispheres, are to be represented. The
cone is supposed to be placed so as to touch the
earth at the central parallel of the country to be
represented.

In maps as ordinarily constructed it is not true that the
upper part is north, the lower part south, the right hand
east, and the left hand west, except in those on Merca-
tor’s projection. Jn all maps due north and south lie along
the meridians, and due east and west along the parallels, since