Nine geometricall exercises, for young sea-men and others that are studious in mathematicall practices: containing IX particular treatises, whose contents follow in the next pages. All which exercises are geometrically performed, by a line of chords and equal parts, by waies not usually known or practised. Unto which the analogies or proportions are added, whereby they may be applied to the chiliads of logarithms, and canons of artificiall sines and tangents. By William Leybourn, philomath.

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Title

Author

Leybourn, William, 1626-1716.

Publication

London :: printed by James Flesher, for George Sawbridge, living upon Clerken-well-green,

anno Dom. 1669.

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http://name.umdl.umich.edu/A48344.0001.001

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"Nine geometricall exercises, for young sea-men and others that are studious in mathematicall practices: containing IX particular treatises, whose contents follow in the next pages. All which exercises are geometrically performed, by a line of chords and equal parts, by waies not usually known or practised. Unto which the analogies or proportions are added, whereby they may be applied to the chiliads of logarithms, and canons of artificiall sines and tangents. By William Leybourn, philomath." In the digital collection Early English Books Online 2. https://name.umdl.umich.edu/A48344.0001.001. University of Michigan Library Digital Collections. Accessed June 17, 2024.

Pages

To resolve the Proposition upon the Projection,

Lay a Ruler to the Zenith-point Z, and upon the Point where the Parallel of Declination cuts the Hour-Circle of Six; the Ruler thus laid will cut the Meridian Circle in r: So the distance r O, being measured upon the Line of Chords, will contain 77 degr. 14 min. which is the Azimuth from the North part of the Meridian.—The distance N r, measured upon the Chords, will give you 12 degr. 46 min. which is the Azimuth from East or West.—And r H, measured upon your Chord, will contain 102 degr. 46 min. his Azimuth from the South.