Map Distances

Distance on a map is the interval between two points on a map. It can either be straight or curved.

MEASUREMENT OF STRAIGHT DISTANCES

(i)         Locate the places involved on the map.

(ii)        Use long ruler to measure the distance between the two points or places. 

(iii)       Relate the distance measured on the map to the scale given and get the ground distance.

MEASUREMENT OF CURVE DISTANCES

This can be done through three methods:

(i)        The use of a pair of divider.

(ii)       The use of a piece of thread.

(iii)      The use of straight edge of a paper.

Among the three methods, the easiest and the best is the use of thread.                   

Use of a piece of thread: Stretch a piece of white thread along the route or curve that is to be measured gradually, carefully and accurately. Carefully follow the curve and do not allow the thread to move out of the curve. Mark the end of the distance on the thread with a biro or a pencil and transfer it to the linear scale or calculate the distance in statement or R.F Scale.

Evaluation Questions:

1. What is a distance?
2. How do we measure distance on map?

DIRECTION: The direction of one place or object from another is expressed by means of compass points or cardinal points. There are 4 cardinal points namely: North, South, Eastand West. But for better accuracy in the measurement of direction, eight cardinal points are used. These include North, North‑East, North‑West, South, South‑East, South‑West, East and West.

PROCEDURES FOR MEASURING DIRECTION                                                                                                                                                (i)        Locate the two places involved on the map.

(ii)       Place your four cardinal points at the location or places given.

(iii)      Use your ruler to join the place you wish to find its direction from the location or reference point.

(iv)       The cardinal point on that line or near it is the direction.

BEARING: The location of one place from another is described as its bearing.

Bearing is expressed in degrees using a protractor, measured from North in a clockwise direction.

Procedures for Measuring Bearing

(i)        Locate the two places involved on the map.

(ii)       Place your four cardinal points at the reference pointbecause you are looking for the bearing of the other town.

(iii)      Use your ruler to join the two places.

(iv)      Place your protractor on the side of the line and the degrees which falls on that line represents the bearing.                    

Evaluation Questions

1. Differentiate between location and bearing.

2. Explain the method of measuring bearing.

General Evaluation Questions:

1. What is bearing?
2. How can you measure a curved distance?
3. Draw the four cardinal points.
4. Describe the shape of the earth.
5. State four proofs of earth sphericity.

Reading Assignment

Read on measurement of direction and bearing in Essential Geography Pgs. 163-164

WEEKEND ASSIGNMENT 

1.         The interval between two points on the map is known as (a) bearing (b) distance

            (c) grid system (d) cardinal points

 2.        One of these is not used for measuring distance (a) straight edge of a paper

            (b) ruler (c) nylon (d) thread

 3.        The first step in the calculation of straight distance is? (a) locate the places involved on the map (b) use a ruler to measure the distance between the two points or places  (c)           relate the distance measured on the map to the scale given and get the ground distance (d) use a thread to get the distance

4.         The cardinal interval between North and East is (a) North – South (b) North – West (c) West – South (d) North – East

5.         The cardinal interval between East and South is (a) North – South (b) East – South (c) South – East (d) North – East

THEORY

1. State the procedures for measuring bearing.

Draw the four cardinal points.