CHAP. XL. The latitude of the place, the Suns altitude and Declination being given, to finde his Azimuth.
FIrst, set the Sphere to the latitude given, and then count your altitude among the parallels of Declina∣tion,
The description and use of the universall quadrat.: By which is performed, with great expedition, the whole doctrine of triangles, both plain and sphericall, two severall wayes with ease and exactness. Also the resolution of such propositions as are most usefull in astronomie, navigation, and dialling. By which is also performed the proportioning of lines and superficies: the measuring of all manner of land, board, glasse; timber, stone. &c. / By Thomas Stirrup, Philomathemat.
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- The description and use of the universall quadrat.: By which is performed, with great expedition, the whole doctrine of triangles, both plain and sphericall, two severall wayes with ease and exactness. Also the resolution of such propositions as are most usefull in astronomie, navigation, and dialling. By which is also performed the proportioning of lines and superficies: the measuring of all manner of land, board, glasse; timber, stone. &c. / By Thomas Stirrup, Philomathemat.
- Author
- Stirrup, Thomas.
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- London :: Printed by R. & W. Leybourn, for Tho. Pierrpont, at the Sun in Pauls Church-yard,
- 1655.
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- Astronomy
- Dialing
- Geometry
- Navigation
- Trigonometry
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"The description and use of the universall quadrat.: By which is performed, with great expedition, the whole doctrine of triangles, both plain and sphericall, two severall wayes with ease and exactness. Also the resolution of such propositions as are most usefull in astronomie, navigation, and dialling. By which is also performed the proportioning of lines and superficies: the measuring of all manner of land, board, glasse; timber, stone. &c. / By Thomas Stirrup, Philomathemat." In the digital collection Early English Books Online 2. https://name.umdl.umich.edu/A93912.0001.001. University of Michigan Library Digital Collections. Accessed May 15, 2024.
Pages
Page 189
and your Declination among the Almicanters, so shall your Meridians become Azimuths, and the work will be the same as in the former Chapter. Only here by the way, I would have you note, that as your parallels and Almicanters changed offices, so must your North and South part of the general Meridian change names, so that when your threed cutteth any parallel at any Azi∣muth, if you count that Azimuth from the South part of the limbe, it shall be the Azimuth from the North; and if you count it from the North part of the limbe, it shall be the Azimuth from the South.
And here also note, that your altitude given must be al∣wayes counted among the parallels of North Declinati∣on; and when the Declination is South, the threed must lie below the horizon, and when the declination is North, it must lie above the same.
As for example, in the latitude of 52 deg. 30 min. let the Declination of the Sun be 11 deg. 30 min. and his al∣titude 25 deg. 56 min. First, I set the Equator 37 deg. 30 min. above the South end of the horizon, and count 25 deg. 56 min. among the parallels of Declination, then I place the threed to 11 deg. 30 min. above the horizon, because the Declination is North, and I finde it cut the parallel of 25 deg. 56 min. at the Azimuth of 74 deg. 22 minutes, counted from the North part of the limbe, and such is the Azimuth from the South, and if you count the Azimuths from the South part of the limbe, you shall finde the threed cut the Azimuth of 105 deg. 38 min. which is the Azimuth from the North.
Again, let the latitude and the declination be the same as before, and the altitude of the Sun 30 deg. 45 min. now the threed being placed to 11 deg. 30 min. counted
Page 190
among the Almicanters above the Horizon, will cut the parallel of 30 deg. 45 min. at the Azimuth of 66 deg. 30 min. counted from the North part of the limbe, and such is the Azimuth from the South.
A third example, let the latitude be the same, and the Suns declination 11 deg. 30 min. South, and his Alti∣tude 13 deg. 20 min. now if you place the threed 11 deg. 30 min. below the Horizon, it will cut the parallel of 13 deg. 20 min. at the Azimuth of 49 deg. 49 min. counted from the North part of the limbe, and such is the Azimuth from the south, as was required.