Old Hampshire Mapped

Magnetic Variation

In the Delineation or Decyphering these Roads upon Copper-Sculptures:

...

10. The several Inclinations of the Road to the one or th'other Hand, are naturally express'd accordingly, and the Points of Bearing are Collected from the peculiar Compass of each Scroll, the Flower-de-luce shewing the North; and when a Compass is repeated in the self same Scroll, a straight transverse Line expresses to what Part of the Scroll either of the said Compasses belong.

In the Illustrations or Historical Part, respecting the General and Particular History, the first thing occuring is the Point of Bearing from the Initial to the terminating Town of the Road; wherein We have advisedly vary'd from the Positions of former Maps; The Original of which Compil'd by Mr. Saxton about an Hundred years a-go, were Projected according to the Meridian of the Magnetick Needle (in England) which then vary'd 12 Degrees from North to East; since which, it has gradually inclin'd to the true Meridian, which in England it respected Anno 1658. but in France Anno 1666. and now varies with Us about 3 Degrees 15 Minutes to the West.