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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Link to this Item

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

Cite this Item

"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

PROP. III. From a Point above, to let fall a Perpendicular upon a right Line given.

LET the Point given be Q, and the Line upon which the Perpendicular is to fall be R S.—First, opening the Compasses to any distance greater then Q X, set one foot in Q, and with the other cross the given Line R S in the Points T and V.—Secondly, (the Compasses unaltered,) set one foot in T, and with the other describe the Arch w w, below the given Line R S.— Thirdly, remove the Compasses to V, (being still at the same distance) and cross the Arch w w in the Point Z—. Lastly, a Ruler laid from Q to Z will cut the Line R S in the Point X. So a Line drawn from Q to X shall be perpendicular to the given Line R S.

[illustration] geometrical diagram