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About: Backstaff     Goto   Sponge   NotDistinct   Permalink

An Entity of Type : yago:Whole100003553, within Data Space : dbpedia.org associated with source document(s)

Type: Thingagentyago:WikicatAstronomicalInstrumentsyago:WikicatMeasuringInstrumentsyago:Artifact100021939yago:Device103183080yago:Instrument103574816yago:Instrumentality103575240yago:MeasuringInstrument103733925yago:Object100002684yago:PhysicalEntity100001930yago:WikicatHistoricalScientificInstrumentsyago:ScientificInstrument104147495yago:Whole100003553 New Facet based on Instances of this Class

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.