MAP WORK: MAP REDUCTION
THE GRID REFERENCE SYSTEM
A grid is a system of numbered squares, formed by vertical and horizontal lines and usually shown on map surfaces. It enables us to determine the position of a place accurately. They also help the map reader to reduce or enlarge the original map extract to given size.
Vertical grid lines are numbered eastward and called Eastings because they increase in value eastward. Horizontal grid lines are called Northings because they increase in value northward. The combination of eastings and northings produces a four-figure or six – figure grid reference as shown below:
The Grid Reference System
The easting is read first while the northing is read last. E.g. the position of A in the grid system is 8242 (Four – grid system) while the position of B in the grid system is 815415 (Six-grid system)
Map reduction simply means reducing the size of the original map. When a map is reduced, the representative fraction becomes bigger.
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