Backstaff
Videos
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 and observ
Davis quadrant, made in 1765 by Johannes Van Keulen. On display at the Musée national de la Marine in Paris.
Quadrant (instrument)
Videos
A quadrant is an instrument used to measure angles up to 90°. Different versions of this instrument could be used to calculate various readings, such as longitude, latitude, and time of day. It was fi
Backstaff
…a version of the backstaff in 1594. Davis was a navigator who was quite familiar with the instruments of the day such as the mariner's astrolabe, the quadrant and the cross-staff. He recognized the inherent drawbacks of each and endeavoured to create a new instrument that could reduce those problems and…
A large frame quadrant at the Beijing Ancient Observatory. It was constructed in 1673.
Ptolemy using a quadrant
A quadrant in a Turkish illustration
Engraving of Tycho Brahe's Mural quadrant in Uraniborg in 1598, picturing the two clocks.