What Is a Backstaff Used for?
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...
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.
What is a cross-staff used for?
The cross-staff is an instrument used to measure angles and altitudes, consisting of a trigonometrically graduated staff and one or more perpendicular vanes moving over it.
Who created the backstaff?
The backstaff was developed by an English Captain named John Davis in the 1590s and–as it enabled a navigator to observe the sun's altitude with safety and ease–was soon widely used for determining latitude at sea.
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