OF THE TERRESTRIAL GLOBE.

1. THE terrestrial globe is a representation of the earth, having the seas and different countries depicted on it, exactly as they are on the surface of the earth.

2. The spindle on which the globe turns is called its axis; but in nature this axis is only imaginary.

3. The extreme points of the axis are called the poles; the one is the north, or arctic; the other the south, or antarctic.

4. The earth is divided into FIVE ZONES ; namely, one torrid, two temperate, and two frigid zones.

5. The torrid zone extends from the equator to the tropic of Cancer northward, and to the tropic

of Capricorn southward; including twenty-threeand-a-half degrees on each side of the equator, making in the whole forty-seven degrees.

6. The two temperate zones lie between the tropics and polar circles, on each side of the equator, being forty-three degrees each; and,

7. The two frigid zones embrace the regions from the polar circles to the poles, extending in each direction twenty-three-and-a-half degrees.

8. The earth is supposed to be surrounded with several imaginary circles, which are actually drawn on the artificial globe, or expressed by wooden or brass work.

9. The equator is a supposed circle of the earth, equidistant from both poles; and it divides the globe into two equal hemispheres, one north and the other south.

10. Meridians are imaginary great circles passing from pole to pole, or over head from north to south.

11. The ecliptic is a great circle in the heavens, in which the sun, or rather the earth, performs its annual revolutions.

12. The ecliptic is divided into twelve signs, which are marked as follows:

13. These signs refer to stars, among which the sun is seen to pass; and the signs, as well

as the ecliptic itself, are drawn on the terrestrial globe only for the convenience of working some problems.

14. The tropics are two circles parallel to, and each twenty-three-and-a-half degrees distant from, the equator; one to the north and the other to the south.

15. The polar circles are parallel to the tropics, and twenty-three-and-a-half degrees distant from the poles.

16. The horizon is expressed by the upper surface of the wooden circle in which the globe stands, and it divides the globe into two equal parts.

17. The zenith of any place is a point in the heavens directly overhead, or above that place, and the nadir is the point opposite to the zenith.

18. The wooden horizon of the globe is divided into three parts: the innermost is marked with all the marks on the mariner's compass; the next has the names, characters, and figures, of the twelve signs; and the third is a calendar of months and days. By the last two are instantly seen the sign and degree the sun is in, during every day in the year.

19. The circumference of the earth and heavens is divided into three hundred and sixty degrees, and each degree is divided into sixty minutes. Half the circumference is one hundred and eighty degrees, and a quarter is ninety degrees.

20. The LATITUDE of any place is its distance from the equator towards either pole, reckoned in degrees and minutes, and may be ninety degrees north or south.

21. The LONGITUDE of any place is its dis

tance from the meridian of London, reckoned in degrees and minutes, and it may be one hundred and eighty degrees east or west.

PROBLEM I.—To find the latitude of any place.

Rule.-Turn the globe, and bring the place to the graduated edge of the brazen meridian; and the degree on the meridian is the latitude north or south, as it may be on the north or south side of the equator.

Ex. Thus the latitude of London is fifty-oneand-a-half north, and of St. Helena nearly sixteen degrees south.

Examples for practice.

What is the latitude of Alexandria in Egypt ?—of Athens? -of Bengal ?-of the Cape of Good Hope?-of Cape Horn? -of Constantinople?-of Edinburgh? of Ispahan?-of Madras?-of Moscow?-of Paris?-of Philadelphia?-of Prague?of Stockholm?-of Teneriffe?-of Vienna ?-of Port Jackson?-and of Mexico?

PROBLEM II.-To find the longitude of any place.

Rule. Bring the place to the brazen meridian, and the degree on the equator shows the longitude from London.

Ex. Thus the longitude of Madras is eighty degrees east; of Lisbon nine degrees west.

Examples for practice.

What is the longitude of Amsterdam?-of Archangel?— of Babelmandeb?-of Bengal?-of Dublin?-of Gibraltar? -of Jerusalem ?-of Quebec?-of Syracuse?-of Tunis? of Turin ?-of Upsal?

PROBLEM III.-The longitude and latitude of any place being given, to find that place.

Rule.-Look for the longitude on the equator, and bring it to the brazen meridian, then under

the given degree of latitude will be the place required.

Ex. Thus the place whose longitude is 80° 10' east, and latitude 31° 11' north, is Alexandria; and the place which has nearly 6° west longitude, and 16° south latitude, is St. Helena.

Examples for practice.

Name the places of which the following are the longitude and latitude-Longitude 30° 17' east, latitude 31° 11' north. -Longitude 79° 50' west, latitude 33° 22' north.-Longitude 8° 30' west, latitude 51° 54' north.-Longitude 4° 5' west, latitude 56° (nearly) north.-Longitude 76° 50' west, latitude 12o south.-Longitude 8° 35' west, latitude 40° 53' north.-Longitude nearly 71° west, no latitude.

PROBLEM IV.-To find the difference of latitude of any two places.

Rule.-If the places are in the same hemisphere, bring each to the meridian, and subtract the latitude of the one from that of the other; if in different hemispheres, add the latitude of the one to that of the other.

Ex. Thus the difference of latitude between London and Madras is 38° 28'; between Paris and Cape Horn is 104° 49'.

Examples for practice.

What is the difference of latitude between Copenhagen and Gibraltar?-between London and the Cape of Good Hope?-between Berlin and Bristol?-between Bengal and St. Helena?-between Madrid and Moscow ?-between Leghorn and Liverpool?-between Pekin and Philadelphia? -How many degrees colder is St. Petersburg than Naples? PROBLEM V.-To find the difference of longitude between any two places.

Rule.-Bring one of the places to the brazen meridian, and mark its longitude: then bring the other place to the meridian, and the number