Grid Reference

Map used in Ireland are drawn up by the Ordnance Survey (O.S.) based in the Phoenix Park, Dublin
The Maps using in the examinations are from the OS series and from all over the country.
To locate a place on the map is the key element of map work.

Aim:
Grid References

Grid references can be given for a point or an area.
Depending on the detail needed the reference to the map can be for an area ( 4 figure grid reference) or a point (6 figure grid reference)
A grid reference can be divided into 3 parts
    Grid letter
    Eastings
    Northings

Grid Letter
Ireland is divided into 25 sub zones.
Each sub zones has a letter of the alphabet
There are 26 letters in the alphabet
One letter is not used this is the i

Eastings
These are the lines on a map, which increase in number as they go towards the east
The lines run DOWN the map
They are the first set of numbers of a grid reference

Northings
These are the lines on a map, which increase in number as they go towards the north
The lines run ACROSS the map
They are the second set of numbers of a grid reference

4 Figure grid
To show an area on a map a 4-figure grid reference is used
What does the grid reference look like?

G 53 07 G = Sub zone letter
53 = 2 numbers from the eastings
07 = 2 numbers from the northings
 
 

The first number of a grid reference is the EASTINGS, followed by the numbers from the northings. This means that you take the numbers from the TOP of the map first and then the numbers along the sides second. An easy way to remember this is the word ATLAS.

AT = Across the Top
AS = Along the Side

The area of E 53 07 is shown below
The bottom left hand corner is the reference used for the area grid reference to be given.

To show a point on a map 6 numbers are used.

            E 530 070

E = The sub zone
530= Eastings
070 = Northings

Tasks

Explain the meaning of Northings and Eastings
Why do we omit the letter i from the sub zones of the national grid?
Using an Ordnance Survey map pick 3 points and 3 areas on the map
Find the grid references.