Map reading skills
Marjorie Henry, Contributor

In an attempt to review some of the skills that you are required to have in map reading, I have been discussing the map reading question of the June 2008 examination. In the event that you missed the earlier lessons, the map extract used in this examination was that of Port Antonio, Jamaica. If you have access to one, please refer to it as I go through the question. If you have none, use any available map extract you may have and apply the skills.

Six-figure grid reference

Section (a) of the question is being discussed. Subsection (i) tested six-figure grid reference and (ii) tested measurement. The remaining two sub-sections of part (a) are as follows:

(iii) Measure the bearing from the lighthouse at Folly Point to the rock on the north coast, called Ship Rock (near Easting 04).

(iv) Determine the approximate compass direction of the hotel at Daniels Harbour (near Easting 11) from the Folly Point Lighthouse.

You should have noticed that (iii) is testing angular bearings and (iv) is testing compass direction. Both are ways in which direction of one point from another may be expressed. Let me revise each of these.

Angular bearings

Angular bearings are measured from the north round towards the east, that is, in a clockwise direction. It follows then that the bearing of a point due east is 90º and of a point dues west is 270º. There are a few simple steps to follow in measuring bearings. Begin by drawing a short north-south line (a vertical line) at the point from which the measurement is to be done.

Use a sharp-pointed pencil please. In this test, it would be at the lighthouse at Folly Point (088707). Draw also a west-east line (a horizontal line) across the vertical line at the same point. Locate the other point between which the bearing must be obtained. In this exercise, it is Ship Rock (041730). Draw a line from where the two lines intersect and extend it to the next point. This would be from the lighthouse at Folly Point to the rock called Ship Rock on the map for this question. Use your protractor to measure the angle made. Remember, you go in a clockwise direction. The answer for this question would be 294º, plus or minus 1.

You must know the correct positions of the cardinal points in order to give the compass direction. They are north, south, east and west. So many students tend to confuse these. To simplify things a bit for those of you who are still in doubt, north is towards the top of the map while south is at the opposite end. When you are indicating west and east, they spell the word WE. North is always shown on the Ordnance Survey map by an arrow. Look for it usually at the bottom of the map extract.

The points halfway between the cardinal points are named by combining the two points that they come between. For example, the point between north and east becomes north-east. There are other points found halfway between these as well. Their names are combinations of the two points they divide. For example, between north and north east is the point north-north east and between east and north-east, the point is east-north east.

When asked to give the compass direction of a place, the same procedure is followed, as for angular bearing, to the point where the line is drawn between the two points. After this, you state the direction. Notice that in the question above, Folly Point lighthouse is the base. Locate Daniels Harbour at 107703. The approximate compass direction would be east-south east.

A word of caution to you. Whenever you are asked to state directions in the examination, it is advisable to give the compass direction as your response. Give angular bearing only if this is asked for.

Consultant in the Protected Agriculture Unit of the Rural Agricultural Development Authority, Webster McPherson, demonstrates popular hydroponics and grow-box techniques to students of Knockalva Agricultural School in Hanover, recently. The Food and Agriculture Organisation officially launched the hydroponics project at the school. - FILE