DRaw a right Line D B representing the Base of your Triangle, which, by help of your Scale of equal parts, make to contain 335. Then upon the Point D, with the distance of 60 degr. of your Line of Chords, describe the Arch k l, and from your Chords take 43 degr. 20 min. the quantity of the Angle at D, and set it upon the Arch∣line from l to k, drawing the Line C D. And because your other given Side B C contains 271 parts, take 271 out of your Line of equal parts, and setting one foot in B, with the other describe the Arch m n, crossing the for∣mer Arch k l in the Point C: then draw the Line C B. So shall you have constituted the Triangle C D B. Lastly, be∣cause it is the Angle at C that is required, take 60 degr. of your Chords, and upon C describe the Arch g h, and taking the distance between g and h, apply it to your Line of Chords,
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
- 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.
- Author
- Leybourn, William, 1626-1716.
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- London :: printed by James Flesher, for George Sawbridge, living upon Clerken-well-green,
- anno Dom. 1669.
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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 16, 2024.
Pages
Page 24
and you shall finde it to reach from the beginning thereof be∣yond the end of the Line; wherefore take 90 degr. the whole Line, and set that distance from g to o; then take the remainder of the Arch o h, and measure that upon your Chord, and you shall finde it to contain 32 degr. which added to 90 degr. make 122 degr. and that is the quantity of the An∣gle at C, which was required.
The Analogie or Proportion is,
As the Logarithm of B C is to the Sine of D,
So is the Logarithm of D B to the Sine of C.