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BACKSTAFF & PLANISPHIRE (nautical instruments)

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BACKSTAFF & PLANISPHIRE (nautical instruments)

Postby aukepalmhof » Thu Oct 05, 2017 3:04 am

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The backstaff is a navigational instrument that was used to measure the altitude of a celestial body, in particular the sun or moon. When observing the sun, users kept the sun to their back (hence the name) and observed the shadow cast by the upper vane on a horizon vane. It was invented by the English navigator John Davis who described it in his book Seaman's Secrets in 1594.
Much more is given on the backstaff by Wikipedia: https://en.wikipedia.org/wiki/Navigation

The”planisphire” In astronomy, planisphere is a star chart analog computing instrument in the form of two adjustable disks that rotate on a common pivot. It can be adjusted to display the visible stars for any time and date. It is an instrument to assist in learning how to recognize stars and constellations. The astrolabe, an instrument that has its origins in Hellenistic astronomy, is a predecessor of the modern planisphere. The term planisphere contrasts with armillary sphere, where the celestial sphere is represented by a three-dimensional framework of rings.

Source: https://en.wikipedia.org/wiki/Planisphere
Solomon Islands 1972 9c sg 216.
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