Trigonometrie. Or, the doctrine of triangles: divided into two books. The first shewing the mensuration of right lined triangles: the second of spherical ... Both performed by that late and excellent invention of logarithms ... Whereunto is annexed (chiefly for the use of sea-men) a treatise of the application thereof in the three principal kinds of sailing. With exact tables of the suns declination ... and tables of the right ascension and declination of some eminent fixed stars ... Also other necessary tables used in navigation / [Richard Norwood].

  • Richard Norwood
Date:
1661
Catalogue details

Licence: Public Domain Mark

Credit: Trigonometrie. Or, the doctrine of triangles: divided into two books. The first shewing the mensuration of right lined triangles: the second of spherical ... Both performed by that late and excellent invention of logarithms ... Whereunto is annexed (chiefly for the use of sea-men) a treatise of the application thereof in the three principal kinds of sailing. With exact tables of the suns declination ... and tables of the right ascension and declination of some eminent fixed stars ... Also other necessary tables used in navigation / [Richard Norwood]. Source: Wellcome Collection.

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    Which converted into leagues, is 25.45 leagues, and fo far you ave to fail from Avin the arch of a great Circle, before you alter-y our courle 7 degrees ‘27 minutes. And inlike fort.you may find it for every fingle degree to be'fuch as by this Table appeareth. JAnoleof Dit. in|.’ Where you may perceive, that having runne sftion.!d, & im | from, A towards E by the-arch of a great Circle eos arate deorees 2. minutes, that is 40; leagues) you alter cela bepds Os your courfe one degree more eafterly than you 48 —48\00—00 began. When you have run 3 degrees, 5.6 minutes, 49——43)02-——02| youalter your.courfe 2.degrees 00, minutes &c. as \gyo—48,03—-56, inthe Table. | 51 48!o5—43 Now for finding the. longitude and latitude of \52—48|07—a5) any of thefe points, it may be done by help of the \53—48|°9—93] perpendicular and angle of pofition: given. As if §4-—-48|!0— 35| there were required the Jongitude and latitude of 55—43|12—04 the point 1; thereis.givenin the Triangle 1D B, 56—15\L2—43\the angle of pofition, at I, andthe perpendicular DB, wherefore by the 5 Cafe I find the complement of the latitude DI, and by the-4 Cafe the difference ? of longitude B DJ, theangle BD A being before known. | Bur notwithflanding all that hath hitherto been-faid, itmay feem hard to dire&t a fhip, and to.keep fucha reckoning as may be agreeable to this amacthod of failing by a great Circle. _ And indeed, as it is in a manner 1m- poflible, fo neither is 1t neceflary,that a fhip fhould alwayes perfeyere ex- adtly.in the arch of a great Circle. Ic may fuffice, and is almoft the fame ia effet, if a fhip, be fo directed, that the go neer this arch. Which how it may be done, and that with fa- qlity, we come now to-fhew in this next problemes | + ee dah Dae few! te + iJ