CHAP. XXXIX. The latitude of the place, the altitude and declination of the Sun being given, to finde the houre of the day.
FIrst, place the planisphere to the latitude given, and seek his declination on the axletree-line among
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.
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- 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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http://name.umdl.umich.edu/A93912.0001.001
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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 June 10, 2024.
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Page 188
the parallels of Declination, then place the threed (paral∣lel to the horizon) to the degree of the Suns altitude counted from the horizon among the Almicanters, and where the threed so placed shall cut the parallel of Decli∣nation, there passeth by the Meridian which giveth you the hour of the day.
As for example, in the latitude of 52 deg. 30 min. the Declination of the Sun being 11 deg. 30 min. and his al∣titude 25 deg. 56 min. I set the Equator 37 deg. 30 min. above the horizon, and count 11 deg. 30 min. upon the Axletree-line; then placing the threed to 25 deg. 56 min. among the Almicanters, I finde it cut the parallel of 11 deg. 30 min. at four hours 8 minutes from the Meridian, and so much was the hour of the day if the observation was made in the afternoon, but if the observation was made before noon, then was it 7 a clock, and 52 min. in the forenoon.
Again, let the latitude and declination be the same, as before, and the altitude given 42 deg. 26 min. now if I place the threed to 42 deg. 26 min. among the Almican∣ters, it will cut the parallel of 11 deg. 30 min. at just two houres from the Meridian, so shall it be either ten a clock in the morning, or two afternoon, according to the ob∣servation.