latitude and longitude
Morden's Hampshire 1695
and
longitude
Morden's map of Hampshire, 1695, has latitude and longitude scales printed in the borders.
The latitude scales on left and right are chequered in 1 minute intervals, and labelled at 5 minute intervals. The longitude scale at the bottom is chequered at 1 minute intervals and labelled at 10 minute intervals. The longitude scale at the top is a scale of the time difference from the prime meridian in London. Note:-
24 hours corresponds to 360 degrees.All the scales are clearly very slanted.
II minutes [time] is 0 degrees 30 minutes West of London,
III minutes is 0d 45m W,
IIII minutes is 1d 00m W, and so on.
Calculations from the positions of the scale marks show that the ratio of latitude to longitude scales is about 1.47. It should be about 1.58 at the latitude of Hampshire; the map is stretched East_West by about 7 percent.
The angle of the 1 degree W meridian is about 14.1 degrees to vertical.
The angle of the 51 degree N parallel is a little less, about 11.2 degrees to horizontal. The lat long 'cells' are not quite rectangular; their internal angles are 93 and 87 degrees instead of 90 degrees. The discrepancy is hardly outwith the errors of the calculations, but the cells may be parallelograms, sheared rectangles.
Summary
Rectangular latitude and longitude scales, but perhaps sheared by 3 degrees W of N.
The 1 degree meridian is aligned 14 degrees west of north.
The map's horizontal scale is stretched 7 percent.
BUT, Morden probably did not plot places with the lat and long scales. It is more likely that he added the scales to an existing map that he copied. The scales might be a good fit to the existing plot.
Measured Values
Measurements in pixels from an image at 150dpi.
Corners A = (68,2749)
B = (57,58)
C = (3184,75)
D = (3183,2751)
Longitude, top 2d 00m = 210
1d 00m = 2616
0d 50m = 3018
Longitude, bottom VII (1d 45m) = 118
IIII (1d 00m) = 1930
II (0d 30m) = 3136
Latitude, left 50d 45m = 2639
51d 00m = 1763
51d 25m = 307
Latitude, right 50d 35m = 2621
51d 00m = 1163
51d 15m = 289
Calculated Values
1 degree longitude, top = 2407
1 degree longitude, bottom = 2414
1 degree longitude = 2410
adjusted for 11.2 degree rotation = 2457
1 degree latitude, left = 3498
1 degree latitude, right = 3498
1 degree latitude = 3498
adjusted for 14.1 degree rotation = 3607
ratio lat/long (adjusted for rotation) = 1.47
compared to correct ration: 1.58 / 1.47 = 1.07
stretch E-W 7 percent
angle of 1 degree meridian = 14.1 degree W of N
angle of 51 degree parallel = 11.2 degrees N of E
internal angles of cell = 92.9 and 87.1 degrees
