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and Applottnents of Lands, between Neighbour and Neighbour, alter the In-of the which, we are told, gave the first Original to Gemrnry and*

Surveying', Absolute Necestity and Use having introduced thele, as Delight andDiversion introduced Astronomy amangst the Cbal’dcans.

And this brings me to another Objection, which may be made against theInstance before laid down: It may be faid, That certainly the Surveyor whichB imployed was very Ignorant,who would choofe to judgeof the LinePQ_ra-ther by itsbearing thanby determining the point Q, by measoringfrom Hand.

G. To this 1 anlwer, What if both the points H, and G, were vanifhed sincethe Down Sarvcy was taken ? What if the whole Face of rhe Country weredianged, säve only the Point P, and the Line P Q_? How shall the Surveyorthen judge of the Line P Q, but by its Bearing ? That this is no extravagantSupposition, we have an Example in /Egypt above-mentioned, where tbe Nilesays all flat before it, and so uniformly Covers all with Mnd, that there is no di-stinction. In soch a Cafe your Bearing rauft certainly help you out, tbere isno other way.

But I anfwer, secondly, to lay that the Surveyor might have determined thePoint Q.by Admeasurement fromG and H, or any otheradjoyningnoted Points,as front F, K, I, Lee. ’tis very true; but then ’tis against our Supposition. I amupon fhewing an Error that ariles from judging of the Line PQ_by MagnetickJBedr-i„g, and to teil me that this might be avoided by another way, is to lay no»thing. I my lelf fhew howit may be avoided, by allowing for the Variation jbut still it is an Emn - till it be avoided.

But, thirdly, if B’s Surveyor do not allow for the Variation of the Needle, hewill never exactiy determine even the Points G, F, H, K, Lee. or any otherPoints in the Plat, but mstead thereof will fall on the Points£, h, f, k.-

From what has been laid down, we may lee the absolute necestity of allow-ing for the Variation of the Magnet, in compnring old Surveys with new ones;for want of which great Disputes may arile between Neighbouring Pro-prietors of Lands: And ü were to be wifhed,that our Honourableand LearnedJttdges would take this Matter into their Consideradon, whenever any busineßof this kind comes before them.

IV. I have invented a Levell with a Tube, with Glasses and a Thread, hang- •^” en Level ;ing between four Points, with a Weight in a Box so contrived, that as foon^J,^^'asthe Instrumentis set down, you have your Point of Horizon with agreat dealp. 1025.

of Exactnesi. I am making another which playeth on one steel Point, ftuidingon a Diamond.

V. An Actountrf <t Boclg Omitted jv/^.The Art öf Levelling by M, n, 74. p. 2277 .

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