earth

COMPASS;
A device for determining the direction of margnetic north.But usually we use it for finding the basic directions NORTH, SOUTH,EAST and  WEST. The magnetic compass which has been in use as an aid to navigation probaly since the 2nd century BC, consists of a magenetic needle balanced on a point allowing it to pivot freely.The south end of the magnet indicates magnetic north as shown on a card called a compass card marked with the points of the compass and fixed beloww it .
For more detail about a comapass; See appendix-1

LATITUDE AND LONGITUDE;
These are the imaginery reference lines.The location of any place can be fixed by known as latitude and longitude.
LATITUDEshown as a horizontal lines is the angular distance in degrees minutes and seconds of a point north or south of the equator.They are the imaginery parellel lines around the earth in the east to west  direction.
LONGITUDE shown as a vetical line is the angular distance in degreed minutes and seconds of a point east or westt of the prime greenwich meridian.
The vertical londitude lines are also known as meridians.They converage at the poles and are widest at the equator about 111 km apart.Zero degrees longitude is located at greenwich england 0 degree.The degree continue 180 degree east  and 180 degree west where they meet and form the international date line in the pacific ocean.
DISTANCE BETWEEN LINES;
If you divide the cirumference of the earth apporximately 25,000 miles by 360 degree, the distance on the earth's surface for each one degree of latitude or longitude is just over 69 miles 111 km at equator.
As you move north or south of the equator distances between the lines of longitude gets shorter until they actually meet at the poles.
MINUTES AND SECONDS;
For precision purposes degree of longitude and latitude have been divided into minutes ' and seconds ".There are 60 minutes in each degree.Ech minute is divided into 60 seconds.For example S.M.A/C college at karachi,sindh pakistan is located at 24 degrees 51 minutes and 05 seconds north of the equator latitude reading and 67 degrees 00 minutes and 10 seconds east of the prime meridian.....