National Grid References

Harrison's Hampshire 1788
NGRs Simple mathematics was used to crudely superimpose the national grid on this old map. The difference between the map projections used by the NGR system and used John Harrison has been ignored. 'Centres' of the the old and the Ordnance Survey maps of the county were superimposed at an average position of twenty or so prominent towns; the orientations and scales were matched by averaging the directions and distances of these places from the centres on each map; it is then possible to draw the NGR from the modern map upon an image of the old. The calculations were done by a computer using a program written by MN, OLDMAPS.exe; fuller notes about the process are provided in the software notes, OLDMAPS.rul.

File HARRIS1.pts has readings of positions of recognisable places on the old map, using (x,y) coordinates on the old map.
Points
file 



@pl Alton @ngr SU77 (SU7173)96 @xy (31.29,24.02)
@pl Basingstoke @ngr SU634527 @xy (28.99,27.78)
@pl Winchester @ngr SU478293 @xy (21.28,19.95)
@pl Andover @ngr SU365458 @xy (18.73,25.73)
@pl Lymington @ngr SZ322954 @xy (13.69,9.64)
@pl Romsey @ngr SU351212 @xy (17.36,18.80)
@pl Fareham @ngr SU575061 @xy (25.69,13.41)
@pl Stockbridge @ngr SU355351 @xy (18.46,21.84)
@pl Petersfield @ngr SU744235 @xy (30.34,18.53)
@pl Havant @ngr SU717062 @xy (30.30,12.86)
@pl Odiham @ngr SU740509 @xy (31.81,27.29)
@pl Christchurch @ngr SZ159925 @xy (8.72,9.08)
@pl Kingsclere @ngr SU525586 @xy (23.74,30.27)
@pl Whitchurch @ngr SU460478 @xy (22.71,27.38)
@pl Fordingbridge @ngr SU150145 @xy (11.77,15.41)
@pl Tangley @ngr SU334524 @xy (17.99,28.47)
@pl Grately @ngr SU275420 @xy (14.92,24.10)
@pl Buriton @ngr SU740200 @xy (29.80,17.56)
@pl Burghclere @ngr SU469610 @xy (22.06,30.27)
@pl Titchfield @ngr SU541058 @xy (23.22,13.19)
@pl Hambledon @ngr SU646151 @xy (27.88,16.30)
@pl Overton @ngr SU514500 @xy (24.16,28.05)

@w 45.73 @h 32.82

@sc 64.9 @m 12


File: HARRIS1.ngr has the results from OLDMAPS.exe

Map HARRIS1

  Data file: HARRIS1.pts
Output file: HARRIS1.ngr


OLDMAPS

Plotting a NGR grid on an old map
version 4.1
MN: 12.2.1997


Given points

 no  place                    ngr         (x,y)

  1  Alton                    SU717396    (   31.29,   24.02)
  2  Basingstoke              SU634527    (   28.99,   27.78)
  3  Winchester               SU478293    (   21.28,   19.95)
  4  Andover                  SU365458    (   18.73,   25.73)
  5  Lymington                SZ322954    (   13.69,    9.64)
  6  Romsey                   SU351212    (   17.36,   18.80)
  7  Fareham                  SU575061    (   25.69,   13.41)
  8  Stockbridge              SU355351    (   18.46,   21.84)
  9  Petersfield              SU744235    (   30.34,   18.53)
 10  Havant                   SU717062    (   30.30,   12.86)
 11  Odiham                   SU740509    (   31.81,   27.29)
 12  Christchurch             SZ159925    (    8.72,    9.08)
 13  Kingsclere               SU525586    (   23.74,   30.27)
 14  Whitchurch               SU460478    (   22.71,   27.38)
 15  Fordingbridge            SU150145    (   11.77,   15.41)
 16  Tangley                  SU334524    (   17.99,   28.47)
 17  Grately                  SU275420    (   14.92,   24.10)
 18  Buriton                  SU740200    (   29.80,   17.56)
 19  Burghclere               SU469610    (   22.06,   30.27)
 20  Titchfield               SU541058    (   23.22,   13.19)
 21  Hambledon                SU646151    (   27.88,   16.30)
 22  Overton                  SU514500    (   24.16,   28.05)
number of points = 22


Centroids of points


(x,y) centroid is  (   22.50,   20.91)
  NGR centroid is  SU491302
    numerical ngr  449.14 130.25


Map scale

scale =     2.62
scale =     2.81
scale =     3.27
scale =     2.71
scale =     3.01
scale =     3.14
scale =     3.19
scale =     2.94
scale =     2.86
scale =     2.77
scale =     3.02
scale =     3.12
scale =     3.09
scale =     3.00
scale =     3.35
scale =     3.05
scale =     2.71

map scale  1 to   297997
or         1 to   297000


Map heading

Map heading
NGR north on map is  3.4 degrees E of map north


Check points

 no  place                    ngr         map

  1  Alton                    SU717396    SU747410
  2  Basingstoke              SU634527    SU672518
  3  Winchester               SU478293    SU456271
  4  Andover                  SU365458    SU370439
  5  Lymington                SZ322954    SZ249951
  6  Romsey                   SU351212    SU342230
  7  Fareham                  SU575061    SU599085
  8  Stockbridge              SU355351    SU369323
  9  Petersfield              SU744235    SU728245
 10  Havant                   SU717062    SU737077
 11  Odiham                   SU740509    SU757509
 12  Christchurch             SZ159925    SZ102926
 13  Kingsclere               SU525586    SU511583
 14  Whitchurch               SU460478    SU486495
 15  Fordingbridge            SU150145    SU182119
 16  Tangley                  SU334524    SU343519
 17  Grately                  SU275420    SU260383
 18  Buriton                  SU740200    SU714216
 19  Burghclere               SU469610    SU461580
 20  Titchfield               SU541058    SU526074
 21  Hambledon                SU646151    SU659175
 22  Overton                  SU514500    SU528517


Map sheet corners

 bottom left SY859640
    top left ST800616
   top right TQ161698
bottom right TV219722


Grid lines

x positions on bottom and top edges,
y positions on left and right edges,
by which to draw lines on map

easting grid lines

Eing      bottom edge    top edge

 390          1.36           3.33
 400          4.72           6.69
 410          8.08          10.05
 420         11.44          13.41
 430         14.81          16.78
 440         18.17          20.14
 450         21.53          23.50
 460         24.89          26.86
 470         28.25          30.22
 480         31.62          33.58
 490         34.98          36.95
 500         38.34          40.31
 510         41.70          43.67
 520         45.06          47.03
 530         48.42          50.39

northing grid lines

Ning      left edge      right edge
  70          2.00          0.74
  80          5.36           2.62
  90          8.72           5.98
 100         12.09           9.34
 110         15.45          12.70
 120         18.81          16.07
 130         22.17          19.43
 140         25.53          22.79
 150         28.90          26.15
 160         32.26          29.51
 170         35.62          32.87



Grid lines

x positions on bottom and top edges,
y positions on left and right edges,
by which to draw lines on map
SCALED x     0.86

easting grid lines

Eing      bottom edge    top edge

 390          1.16           2.85
 400          4.04           5.72
 410          6.91           8.59
 420          9.79          11.47
 430         12.66          14.34
 440         15.53          17.22
 450         18.41          20.09
 460         21.28          22.97
 470         24.16          25.84
 480         27.03          28.72
 490         29.91          31.59
 500         32.78          34.46
 510         35.65          37.34
 520         38.53          40.21
 530         41.40          43.09

northing grid lines

Ning      left edge      right edge
  70          1.71          0.64
  80          4.59           2.24
  90          7.46           5.11
 100         10.33           7.99
 110         13.21          10.86
 120         16.08          13.74
 130         18.96          16.61
 140         21.83          19.49
 150         24.71          22.36
 160         27.58          25.23
 170         30.45          28.11



Scale line

scale line length    64.90 cm
representing   12 miles
scale 1 to    29757

Harrison's Hampshire 1788, index grid
General index
Old Hampshire Mapped
Map HMCMS:FA1996.34