Map
Reading
Important
notice: All maps on this web site are diagramatic only.
They should not be used in place of a proper Ordnance
Survey map. To do so could be dangerous.
The
National Grid
Divides
the country into 1km squares.
A Grid Reference has 2 letters followed
by 6 numerics e.g. SX604699.
The grid letters (SX) can
be omitted as the dimensions of Dartmoor are less than
100 kilometres so the grid numbers will not be duplicated.
In other words all of Dartmoor is covered by the grid
letters SX, (not to be
confused with Essex).
The grid numbers are two groups of 3, the first three
604 are the Eastings and
the final 3 699 the Northings.
I understand them more clearly as x
and y axis, as in geometry,
the first 3 numbers are a point along the x
axis the final 3 numbers are a point up the y
axis. You could also think of it as 'along the corridor
and up the stairs'.
So
to pinpoint (within 100 metres or so) Nuns Cross, otherwise
known as Siwards Cross at Grid Reference 604
699
you locate on the Map the left, or western side, of
the grid marked 60, then
find the bottom or southern side of the grid marked
69. The place you want
is inside this box.
You've found 60 but you
need to be at 604 therefore
move to the right or East (along the corridor) 4/10ths
of the box, from this point move up, or North (up the
stairs) from 69 9/10ths
of the box to 699. You
are now at 604 699 Nuns
Cross.
Every
photograph has this 6 digit Grid Reference so you know
where the photographer was standing. What you need to
know now is the direction the camera was pointing from
that position. This is the Bearing and this is the other
number by each photograph.
Bearings
A
Bearing is a horizontal angle fixing a direction in
respect to North.
North
There is Magnetic North, which your compass needle points
to,and Grid North, the vertical lines of the grid on
your map. As the map tells us 'Magnetic North is estimated
at 3 degrees west of Grid North for 2002 decreasing
by about 0.5 degree in four years'.
To simplify things the bearings given are broadly based
on Magnetic North, this is because you are likely to
go to a Grid Reference position, set your bearing on
the Compass point to the bearing stated on the photograph
then face the bearing and compare what you see with
the photograph you have printed. The bearing will be
precise enough for our needs without making adjustments
for declination.
Facing
a bearing
Your compass should have a base plate and a dial like
the diagram below:
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