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
http://name.umdl.umich.edu/A64223.0001.001
Cite this Item
"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 14, 2025.
Pages
descriptionPage 16
PROBL. 9.
The declination and altitude of the Sun or any
Star, given to find their Azimuth in Northern
declination.
Lay the thread to the altitude numbred on
the limb of the moveable piece from 60/0
toward the end (and when occasion requires,
continue your numbring forward upon the
loose piece) and take the declination from
your line of altitude; with this distance run
one point of your Compasses along the line
of Azimuths (on that side the thread next the
head) until the other just touch the thread,
then the former point gives the Azimuth
from South. Ex. gr. at 10 deg. declination
North, and 30 deg. altitude, the Azimuth
from South is 64, deg. 40 min.
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