LATITUDE, LONGITUDE AND ZONES 31. Telling where places are.—How do we tell someone where a house is located in a city? First we need a starting point of some kind. In the city of Washington this starting point is furnished by two streets which cross each other, one going east and west, and the other going north and south. Name these streets. (Fig. 43.) All that part of the city north of East Capitol Street and east of North Capitol Street is called Northeast. The streets named with numbers run parallel to North Capitol, and the streets named with letters run parallel to East Capitol. The houses in the block from East Capitol Street to A Street have num bers below 100, those between A and B Streets have numbers beginning with 100, and so on, each block beginning with a new hundred. The same thing is true of the house numbers on the streets with letter names. Therefore a house numbered 220 Third Street, N. E., must be on Third Street between B and C. Thus we can locate a house in Washington by number, street, and section.
In much the same way we locate a city, a lake, or a river, that is, by giving its dis tance north or south from the equator and its distance east or west of some particular place. (Fig. 44.) 32. you look at the map (Fig. 45.) you will see some lines running across the map. All parts of each line are the same distance from the equator. These are called parallels and are used as a means of telling how far a place is north or south of the equator. The distance from the equator to the North Pole or from the equa tor to the South Pole is divided into ninety equal parts, and each part is called a degree of latitude. A degree of latitude equals about seventy miles. Each parallel on the map marks a certain degree of latitude, or distance from the equator. Twenty de grees north latitude means twenty degrees north of the equator. Twenty degrees south latitude means twenty degrees south of the equator. How many miles north or south would that be? 33. Longitude.—Now look for the lines on the map that run north and south. These are called meridians. We use them to measure distances east and west of some particular place. Take a ball or some other round object and mark on it the places for the north pole and for the south pole. Now draw some straight lines from pole to pole. You see that they all come together at the poles and become farther and farther apart as they come near the equator. We can draw a meridian from pole to pole on the map, and make it pass through some city which we will choose as a point from which to measure. Then we say that the meridian of some other place is so many degrees east or west of the city whose meridian we have marked.
When distance is measured in degrees north or south it is called latitude; when. it is measured in degrees east or west, it is called longitude. The numbers of degrees of latitude are on the sides of maps, and the numbers of the degrees of longitude are at the top and bottom. Look on the globe
or at a map (Fig. 48) and see the parallels of latitude and the meridians of longitude. One degree of longitude is about seventy miles wide at the equator. As we go toward the poles, the meridians draw closer and closer together until they all meet at the poleS.
The longitude on our maps is counted east and west of the meridian that passes through an observatory in the city of Greenwich, now a part of the city of London, England. (Fig. 40.) If a place is seventy degrees west of the meridian of Greenwich, we say it is seventy degrees west longitude, or 70 degrees W. If it is thirty degrees north of the equator we say it is thirty degrees north latitude or 30 degrees N. See how much this is like the location of houses in Washington City.
There are 360 degrees of longitude around the world, going from Greenwich around to Greenwich again. How many degrees of latitude are there in going around the world, by passing through both poles? 34. Zones.—There is still another way of locating places. The surface of the earth is divided into five wide belts run ning around the earth east and west, just as the parallel lines do. These belts are called zones. When we say that a place is in the Temperate Zone or in the Frigid Zone or in the Torrid Zone, we mean that it is on that part of the earth's surface.
Look at the map (Fig. 45) and name the zones.
You have noticed that in our part of the country the sun is higher in the sky at noon in summer than it is in winter. If we went far enough south, we should reach a place where, on at least one day in the summer time, the sun would be directly overhead at noon. All the land on which the sun shines directly down at noon at some time in the year is called the Torrid Zone, meaning hot. The Torrid Zone extends 231 degrees, or about 1600 miles, on each side of the equator. The lands in this zone are hot, and there is no winter there. In some places the trees stay green all the year. No part of the United States is in the Torrid Zone.
In Eskimo land, the sun shines all night in the summer time, while in winter there are some days when the sun does not rise at all. All that part of the world in which there are days, .or even one single day when the sun does not rise at all, is called the Frigid Zone, meaning cold. There are a North Frigid Zone and a South Frigid Zone, of which the centers are the North and South Poles. The land between each of the two Frigid Zones and the Torrid Zone is called the Temperate Zones, be cause the climate here is not so hot as in the Torrid Zone nor so cold as in the Frigid Zone. As a matter of fact, some parts of the Temperate Zones are as hot during part of the summer as the Torrid Zone, and in winter are cold like the Frigid Zone. There is a North Temperate Zone and a South Temperate Zone. Which Temperate Zone has the most land?