PROBL. 9.
The Latitude, Declination of the Sun, and his Azimuth from South, given to finde the Suns Altitude at that Azimuth.
As the radius to the cosine of the Azimuth from south, so is the co-tangent of the lati∣tude,
The semicircle on a sector in two books. Containing the description of a general and portable instrument; whereby most problems (reducible to instrumental practice) in astronomy, trigonometry, arithmetick, geometry, geography, topography, navigation, dyalling, &c. are speedily and exactly resolved. By J. T.
About this Item
- Title
- The semicircle on a sector in two books. Containing the description of a general and portable instrument; whereby most problems (reducible to instrumental practice) in astronomy, trigonometry, arithmetick, geometry, geography, topography, navigation, dyalling, &c. are speedily and exactly resolved. By J. T.
- Author
- Taylor, John, 1666 or 7-1687.
- Publication
- London :: printed for William Tompson, bookseller at Harborough in Leicestershire,
- 1667.
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- Subject terms
- Mathematics -- Early works to 1800.
- Navigation -- Early works to 1800.
- Dialing -- Early works to 1800.
- Link to this Item
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http://name.umdl.umich.edu/A64223.0001.001
- Cite this Item
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"The semicircle on a sector in two books. Containing the description of a general and portable instrument; whereby most problems (reducible to instrumental practice) in astronomy, trigonometry, arithmetick, geometry, geography, topography, navigation, dyalling, &c. are speedily and exactly resolved. By J. T." In the digital collection Early English Books Online. https://name.umdl.umich.edu/A64223.0001.001. University of Michigan Library Digital Collections. Accessed May 6, 2025.
Pages
Page 55
to the tangent of the Suns altitude in the equator at the Azimuth given. Again,
As the sine of the latitude is to the sine of the Suns declination, so is the cosine of the Suns altitude in the equator (at the same Azi∣muth from East or West) to a fourth ark.
When the Azimuth is under 90, and the latitude and declination is under the same pole, adde this fourth ark to the altitude in the equator. In Azimuths exceeding 90, when the latitude and declination is under the same pole, take the equator altitude out of the fourth ark. Lastly, when the latitude and declination respect different poles, take the fourth ark out of the equator altitude, and you have the altitude sought.