8 T, fand ile Doclinmtion F a Plane.

netical Needle. For take any Board that harh one ſide ſtiaighit, anddrauj as in che laſt Diagtam the Line H O parallel to chat ſide, and theLine Z M perpendicular unto it, and on che Center E make a SemicircleHMO: chis done, hold che Board to che Plane,(o as FH O may be paral-lel to B D the Horizontal Line on the Plane, and che Board parallel to theHorizon: chen che Sun ſhining upon it, hold out a Thred and plummet,lo as the Thred being Vertical, che ſhadow of the Sun may fall on cheCenter Z; and draw che Line of Shadow, A Z, repreſenting the commonSection Which the Azimuth of the Sun makes With the Plane of the Ho-rizon, and let another take the Altitude of the Sun at the ſame inſtant;ſo by relolving a Triangle, as I ſhewed before, you may find what Azi-much the Sun was in when he gave ſhadow upon A Z.

Suppoſe the Azimuth to be 72 gr. 52 n. from the North to the Weſt-ward, and therefore 17 gr. 8 n. from the Weſt, we may allow cheſe 1 gr.8 m. from A unto V, and draw che Line Z V, and ſo wWe have the true Weſtpoint of the prime Vertical Line e then allowing 90 gr, from V unto 8,we haue the douth point of the Meridian Line Z.&, and the Angle HZ Vſhall give the Declination of the Plane from the Vertical, and the AngleO28 the Declination of the Planefrom the Meridian.

Or we may take out only the Angle A Z H, which che Line of Shadow

makes with the Horizontal Line of the Plane, and compare it with the

Angle A Z V, Which the Line of Shadow makes with the prime Vertical.And ſo here, if A Z Vche Suns Azimuth ſhall be 15 gr. 8 m. paſt theWeſt, and yet the Line of Shadow R Z. 7 gr. 12 in. ſhort of the Plane, cheDeclination of the Plane ſhall be 24 gr. 20 h. as may appear by the ſiteof the Plane and the Circles.If che Altitude of the Sun be taken at ſuch time as the Shadow of theThread falleth on B Dor H O, and then a Triangle reſolved, the Declina-tion of the Plane will be ſuch as the Azimuth of the Sun from the PrimeVertical. öIf at ſuch a time as the Shadou/ falleth on M Z, che Declination will beſuch as the Azimuth of che Sun from the Meridian.If it be a fair Summers day, you may firſt find what Altitude the SunWill have when he cometch to the due Eaſt or Weſt, and then expect untilhe come to chat Altitude, ſo the Declination of the Plane ſhall be ſuch asthe Angle contained between the Line H O and the Line of the Shadow.Having diſtinguiſhed the Planes, the next care will be for the placing ofthe Style, and che drawing of the Hour: lines.The Style will be as the Axis of the World, ſometimęs parallel 15 thePlane