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Hearings with the trne meridian.

Bearings with a meridian of 33 °30 ' of west •Variation

CHAIN'S.

North 3 o° weft 5

North 8

North 8o° eaft 5

North 45 i° weft 10

North 2 3 i° weft 4

CHAINS,

North 6i° weft 5

North 23*° eaft 8

North 7 6\° eaft 5

North 22° weft 10

North 4

Then fix^the irjftrument at the A pit, and run off thefirft bearing and diftance north 6\° weft 5 chains, andthe other following ones in regular order, and the end ofthe laft, .north 4 chains, will be the place on the furfacewhere the pit muft be funk, to hit the extreme point ofthe excavation.

To find the antiquity of a plan by its delineatedmeridian.

As the magnetic meridian has, for a great number ofyears paft, been veering about to the weft, hence plansconftru&ed at different times muft have their magneticmeridians of different variation ; thofe that are of themoft ancient conftruction will have their meridians moreeafterly than thofe of a more modern date. Should aplan be found to have been conftrufted by a meridianhaving n° 15' of baft variation, it will be reafonable tofuppofe it has been made about the year 1576; for atthat time the magnetic meridian had n° 15' of eaft va-riation (fee p. 117): Or, if its meridian is found to have

20 °