"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 ...
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longitude, latitude, and time of day. It was originally proposed by Ptolemy as a better kind of astrolabe. Several different variations of the instrument were later produced by medieval Muslim astronomers. Mural quadrants were important astronomical instruments in 18th-century European observatories, establishing a use for positional astronomy." - (en.wikipedia.org 03.10.2022)
