<?xml version="1.0" encoding="utf-8"?><mads xmlns="http://www.loc.gov/mads/" xmlns:mods="http://www.loc.gov/mods/v3" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.loc.gov/mads/
mads.xsd"><authority><topic authority="http://AATesaurus.cultura.gencat.cat/aat/getty_en">octants</topic></authority><related type="broader"><topic>vertical angle measuring devices</topic></related><related type="broader"><topic>astronomical instruments</topic></related><variant type="other"><topic>octant</topic></variant> <note xml:lang="en"><![CDATA[ Reflecting navigational instruments used for measuring the altitude of celestial bodies and having an arc of 1/8 of a circle, but due to their reflecting properties can measure up to 90 degrees; invented in the 1730s and used into the 19th century when superseded by sextants. ]]></note></mads>