A MAP is a picture of the whole, or of a part, of the Earth’s surface,
on a plane or level. Generally the top of a map represents _north_;
the right hand side, _east_; the bottom, _south_; the left hand side,
_west_. West, east, north, and south, are called the Cardinal Points.
Young persons in studying maps, imbibe an idea that the top of a
map represents the _highest part of a country_; but this is a great
mistake, as will be at once seen, by looking at the maps, and finding
many rivers flow north, and recollecting that water cannot flow up
hill. That part of a country is the most elevated, which contains
mountains, and where rivers have their source.
_Cities_ and _towns_ are represented on maps by an o; _rivers_,
by black lines running irregularly; _mountains_, by dark shades;
_deserts_, by clusters of small dots; _boundaries_, by dotted lines.
The AXIS of the earth is an imaginary line passing through its centre
from north to south. The extremities of the Axis are called the POLES.
The EQUATOR or EQUINOX, is an imaginary circle, surrounding the Earth
from west to east, at an equal distance from the poles. See Map of the
World, fig. 2.
A MERIDIAN, or Line of Longitude, is a circle crossing the equator at
right angles, and passing through the poles. See fig. 4.
PARALLELS OF LATITUDE, are lines, drawn across maps, representing
circles equally distant in every part from the equator. See fig. 3.
The TROPICS are two circles parallel to the equator, at about 23
degrees and 28 minutes from it. The northern is called, the _Tropic of
Cancer_; and the southern, the _Tropic of Capricorn_. See fig. 2.
The POLAR CIRCLES are drawn at 23 degrees and 28 minutes from the
poles. The northern, is the _Arctic_, and the southern, the _Antarctic
Circle_. See fig. 2.
A DEGREE is the 360th part of a circle, and contains 69½ English
miles; each degree is divided into 60 equal parts, called minutes; and
each minute into 60 equal parts, called seconds. They are marked (°)
degrees, (’) minutes, (”) seconds.
The LONGITUDE of a place, is its distance from any given meridian, as
Washington, London, or Greenwich, and is reckoned in degrees, &c. on
the equator. Longitude is marked in figures, either on the equator, or
at the top and bottom of the map, and can be reckoned only 180 degrees
east or west, that distance being half of a circle. _Longitude, on most
of these maps, is reckoned from the meridian of Greenwich, near London._
The LATITUDE of a place is its distance in degrees, &c. north or south
from the equator, and is expressed in figures on the sides of the map.
Latitude can never exceed 90 degrees.
The ZONES are portions of the Earth’s surface divided by the tropics
and polar circles. There are five zones, viz. one torrid, two
temperate, and two frigid zones. See Map of the World, fig. 1.
The _Torrid Zone_ is included between the tropics, and is distinguished
for extreme heat, and luxuriant vegetation; the climate is generally
unhealthy.
The _Temperate Zones_ are included between the tropics and the polar
circles; they have a healthy climate, and produce the greatest
abundance of the most useful commodities.
The _Frigid Zones_ lie between the polar circles and the poles, and are
remarkable for extreme coldness of climate and general barrenness of
soil.
A HEMISPHERE is half a globe. The map of the world is divided into
the western and eastern Hemispheres; and the equator divides it into
northern and southern Hemispheres.
The DIAMETER of the earth, _that is, the distance through its centre_,
is about eight thousand miles; and its CIRCUMFERENCE, _that is, the
distance round it_, is about twenty-five thousand miles.
_In tracing the relative situation of places_, the pupil must remember
to follow the direction of the parallels and meridians, and not be
governed merely by the apparent direction of one place from another.
Thus, on the map of the world, Iceland appears north from Newfoundland,
but it is northeast. Therefore, the direction towards the top and
bottom of maps is not always _exactly_ north and south; but to go north
you must proceed toward the north pole; and south, toward the south
pole;—following the direction of the lines.
The preceding principles should be rendered as perfectly
familiar to the pupil as the letters of the alphabet.
To secure this object, the learner is required, in
the following pages, to define a continent, an ocean,
latitude, longitude, &c. in connexion with the subject
of questions on the maps. It will also be useful, after
the pupil has passed the map of the world, frequently to
require similar definitions to be repeated, when naturally
suggested by the subject, and thus impress the learner
with the necessity of being always prepared to answer
them. This method furnishes a general review of Elemental
Geography through the whole course of studying the maps,
and will give variety and pleasure to the exercise.