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Using The Basic Roamer to plot and give a precise location is really very easy.

The Basic Roamer 5 is suitable for use with all 1:50,000 scale maps. In the British Isles we use Ordnance Survey Landranger maps of which there are 204 in total.

Each map covers an area of 25 x 25 miles (40 x 40 Km.) A series of vertical and horizontal numbered lines will be found on these maps, called grid lines they form part of the National Grid, which is based on an imaginary line to the West of Lands End. Further to this, each 10 x 10 Km area has a two letter prefix, which enables a uniqueness when plotting a map reference.

The examples below show how to calculate first a six then an eight figure map reference.

Let us use The Basic Roamer5 to plot the six figure map reference: 093 447

So, with the map open and laid flat, find the vertical grid line (Easting 09) and the parallel grid line (Northing 44) Place The Basic Roamer onto the map, with the top Right hand corner at the point of the grid square where the vertical line (09) joins the horizontal line (44) Now move The Basic Roamer along, towards the right (Eastwards = Easting) to a point which is 3 tenths of the grid square from gridline (09) This will give you the first part of the map reference 093. Maintain this part of the plot, by holding The Basic Roamer flat against the map, now slide it towards the top of the map (Northwards = Northing) to a point which is 7tenths of the grid square, this will give you the second part of your ref: 447. The map reference therefore is 093 447

Highlighting the Western edge of the hamlet shown below.

Six figure map reference, 093 447

The second joins the horizontal line 76. Now move The Basic Roamer along, towards the right (Eastwards = Easting) to a point which is 31_/2 tenths of the grid square from gridline 74. This will give you the first part of the map reference 7435. Maintain this part of the plot, by holding The Basic Roamer flat against the map, now slide it towards the top of the map (Northwards = Northing) to a point which is 91_/2tenths of the grid square, this will give you the second part of your ref: 7695 example allows us to utilize the The Basic Roamerto plot an eight figure map reference: 7435 7695

For the purpose of this excercise we are utilizing Ordnance Survey Landranger map number 147
Again, open your map to expose the top Left hand portion in this case, find the vertical grid line 74 and the parallel grid line 76. Place The Basic Roamer onto the map, with it's top Right hand corner at the point of the grid square where the vertical line 74

The complete map reference therefore is 147 / 7435 7695

As can be seen, this highlights precisely the famous Devils Bridge waterfall found next to the A4120/B4574 road junction in the Welsh countryside.

OS map 147/7435 7695

Additional subjects will be featured in the near future.

Certain images produced from the Ordnance Survey Get-a-map service. Images reproduced with kind permission of Ordnance Survey and Ordnance Survey of Northern Ireland© Crown copyright.