Page:Maury's New Elements of Geography, 1907.djvu/138

From Wikisource
Jump to navigation Jump to search
This page has been validated.
134
LATITUDE AND LONGITUDE; REVIEW.

the United States. Most of the land is owned by Americans. The natives are civilized. There are schools and churches. The products of the islands are sugar, rice, and coffee. Honolulu is the capital.

For Recitation.—For what is Australia noted? What are the chief products of New Zealand? Name the chief exports of the East India islands. What islands in the Pacific belong to the United States?


LATITUDE AND LONGITUDE.

In measuring the length of your schoolroom you find yards and feet very convenient measures. For measuring the distance from one town to another miles are convenient. But for measuring great distances on the surface of the earth another measure is used called degree.

Let me explain what a degree is. If you should travel round the earth from east to west, you would go in a ring or circle. If you went round it from north to south, and from south to north again, you would also go in a circle.

Such circles are not really drawn on the surface of the earth. We only imagine them, and they are called imaginary circles. They are represented by the lines that you see on the map of the hemispheres, and on other maps. These lines are drawn from north to south, and from east to west. Those drawn from north to south are called meridians. Those from east to west are called parallels.

Every circle is supposed to be made up of 360 equal parts. Each one of the parts is called a degree.

Distance north or south is called latitude. Distance east or west is called longitude.

In measuring all distances, we need, of course, a line or a point from which to reckon.

We measure longitude from the meridian that passes through Greenwich, near London. We reckon it east and west halfway round the earth.

The starting line for measuring latitude is the equator, and, therefore, when we speak of the latitude of a place, we mean that it is so many degrees north or south of the equator.

On page 124 you will see the meridians drawn across the map from north to south. On the top margin find the meridian numbered 0. This is the meridian of Greenwich. All places through which this meridian passes are said to have no longitude. This is only another way of saying that they are neither east of the line nor west of it. The next meridian west of this line of no latitude is marked 10. This number means that all places on this meridian are 10 degrees westward of the Greenwich meridian.

Now look to the east of the Greenwich meridian on map, page 124. You see a number of meridians here also. Each one is 10 degrees from its neighbor. They might be drawn one or two or any number of degrees apart.

Look again on map on page 124, and notice the parallels. They also are drawn 10 degrees apart, though they, too, might be drawn any other number of degrees apart.

Now suppose I should say that a ship had sailed to some islands in the Pacific ocean that are 180 degrees from Greenwich. Looking at the map, you would see that the meridian of 180 passes through two groups of islands, the Fiji and the Aleutian. But here you would be puzzled. How could you tell whether I meant the Aleutian or the Fiji islands. I must tell you the latitude as well as the longitude. If I say a ship sailed to the islands in the Pacific that are 180 degrees westward from Greenwich, and nearly 20 degrees south of the equator, you can find the exact place on the map, and you see that the islands meant are the Fiji islands.

Just so any place whatever may be found, if we know its latitude and longitude.

TOPICAL REVIEW.

Topical Review.—Let pupils write or tell what they know about any one of the following topics:

Direction—Measurement of distance—Maps—Shape of earth—Forms of land and of water—Rotation of earth —Revolution of earth—Zones—Occupations of men— Government—Religion—Races of men—Conditions of society.

Early settlement of North America—Surface of the United States—Occupations in the United States—Great crops of different portions of United States—The great cities (Seaports—Inland—Lake Ports).

The climate of Europe—Products—Manufactures— Exports—Imports. The products of Asia—Its exports —Animals, wild and useful. Climate and products of Africa—Exports, Plants and animals of Australia. Products and exports of Oceania.