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 1, 2024.

Pages

The Analogie or Proportion.

As the Radius 90 degr. is to the Co-sine of the difference of Longitude 76 degr. 50 min.

So is the Co-sine of the Latitude given 38 degr. 30 min. to the Co-sine of the Distance required 52 degr. 41 min.

Thus suppose the two Places to be the Island of S. Thoma, ly∣ing under the Aequinoctial in the Longitude of 33 d. 10 m. and London under the Parallel of 51 d. 30 m. of North Latitude, having 20 degr. of Longitude, their Distance by the former Proportion will be found to be 52 degr. 41 min. which, con∣verted into Miles, gives 3161 miles for their Distance.