Map reading and field study

Give direction in terms of compass bearing and the 16 points of the compass;

FOCUS QUESTIONS

I What is a compass? I How to give compass direction. I How to give direction in terms of compass bearing.

A compass is a device that indicates direction. It is one of the most important instruments for navigation.

Magnetic compasses consist of a magnetized needle that can rotate so it lines up with the Earth’s magnetic field. The ends point to what are known as magnetic north and magnetic south.

COMPASS DIRECTION

There are four cardinal points of the compass: north, east, west and south. They are constant.

HOW TO REMEMBER

With north pointing ahead, ‘west’ and ‘east’ make the word ‘we’.

I The direction halfway between north and west is described as north-west.

I The direction halfway between south and east is described as south-east. I The direction halfway between south and west is south-west. I The direction halfway between north and east is north-east. These are four primary intermediate or intercardinal points NE, SE, SW, NW.

THERE ARE ALSO SECONDARY INTERCARDINAL POINTS

I Halfway between each cardinal point and intercardinal point. I These are north-northeast, east-northeast, east-southeast, south-southeast, ... and so on. Eight of them.

FINDING COMPASS DIRECTION STEPS

1. Read the question carefully. 2. Locate both places on the map. 3. Connect both places, using a straight line.

4. Draw the cardinal points through the starting point.

5. Give the compass direction using the 16-point compass.

COMPASS BEARING

A bearing is a measurement of direction between two points. Bearings are a more precise way to indicate direction, with the use of a protractor. Bearings are generally given in one of two formats, an azimuth bearing or a quadrant bearing.

A compass quadrant bearing have both numbers and names.

To find compass quadrant bearing, it requires three steps.

I First, decide whether the arrow is closer to N or to S. I Next, decide whether it’s closer to the E or the W. I Finally, measure the angle. I Now you have the compass quadrant bearing. For example, S 77° E.

Please note that you always write the N or S first, then the angle, and then the E or W.

The advantage of the compass quadrant bearing is that it gives you the old-fashioned sense of north, northeast, etc. together with a precise angle. We will look at the azimuth bearing in this lesson. An azimuth bearing uses all 360° of a compass to indicate direction. As you know, a circle has 360°, with 180° in each half of the circle.

A bearing will be a number, between 0 and 360°, which represents the direction that one location is when viewed from a starting location.

The compass is numbered clockwise with north as 0°, east 90°, south 180°, and west 270°. So, a bearing of 42° would be north-east and a bearing of 200° would be south-west, and so on.

Bearings are always calculated based on north being zero degrees, and degrees are then counted moving clockwise around the circle from there.

As was said, bearings can be done using a protractor.

This is the steps involved in calculating bearing between two points is as follows:

I Draw a line between the two points which will be long enough to see using your protractor.

I Place the protractor on the map, with 0 degrees pointing north, and the centre of the protractor on the starting location.

I Read on the protractor the degrees that the line between the two points follows.

I If your protractor only has 180°, where the bearing is greater than 180°, you may need to measure the angle from 360 to your line, and then subtract that from 360° in order to calculate the bearing.

COMMON ERRORS IN FINDING COMPASS BEARING

A common error with directions is forgetting to use the ‘Never Eat Soggy Weetabix’ and getting the north, south, east and west labels in the wrong points on the compass.

FOR BEARINGS, COMMON ERRORS ARE:

I Not placing the protractor on the starting point for determining the bearing of the second point. I Not placing the protractor with zero pointing north, as indicated by the orientation on the map. I Incorrectly calculating a bearing when it is greater than 180 degrees. If the direction is between south and north on the western side, the bearing must be greater than 180° and less than 360°. Please bear in mind that these steps must be followed. Steps that must be followed: 1. Connect the two points with a pencil line. 2. Draw a north line FROM the point where there needs to be measured.

3. Position the protractor with 0° towards the north line and the medium to be the point where it should be measured from.

4. Measure the angle from the north line to the right (clockwise) to the connecting line (pencil line from step 1). Finding the bearing of A from B Here is an example. Imagine that you are at point B. You need to travel to point A. On which bearing should you travel? 1. Start by facing north. 2. Move clockwise to face A. 3. Measure the clockwise angle between the north line and the line AB. Next lesson, we will look at reducing and enlarging a section of the map.