Editing Hypatia (section)

===Reputed inventions===
[[File:Astrolabio (16787706916).jpg|thumb|Hypatia is known to have constructed [[Astrolabe|plane astrolabes]],{{sfn|Deakin|2007|pages=102–104}} such as the one shown above, which dates to the eleventh century.]]

One of Synesius's letters describes Hypatia as having taught him how to construct a silver [[Astrolabe|plane astrolabe]] as a gift for an official.{{sfn|Bradley|2006|page=63}}{{sfn|Deakin|2007|pages=102–104}}{{sfn|Deakin|1992|page=22}}{{sfn|Booth|2017|pages=111–113}} An astrolabe is a device used to calculate date and time based on the positions of the stars and planets. It can also be used to predict where the stars and planets will be on any given date.{{sfn|Deakin|2007|pages=102–104}}{{sfn|Booth|2017|page=111}}{{sfn|Pasachoff|Pasachoff|2007|page=226}} A "little astrolabe", or "plane astrolabe", is a kind of astrolabe that used [[stereographic projection]] of the celestial sphere to represent the heavens on a plane surface, as opposed to an [[armillary sphere]], which was globe-shaped.{{sfn|Emmer|2012|page=76}}{{sfn|Booth|2017|page=111}} Armillary spheres were large and normally used for display, whereas a plane astrolabe was portable and could be used for practical measurements.{{sfn|Booth|2017|page=111}}

The statement from Synesius's letter has sometimes been wrongly interpreted to mean that Hypatia invented the plane astrolabe,{{sfn|Oakes|2007|page=364}}{{sfn|Theodore|2016|page=183}} but the plane astrolabe was in use at least 500 years before Hypatia was born.{{sfn|Bradley|2006|page=63}}{{sfn|Deakin|2007|pages=102–104}}{{sfn|Theodore|2016|page=183}}{{sfn|Booth|2017|pages=112–113}} Hypatia may have learned how to construct a plane astrolabe from her father Theon,{{sfn|Emmer|2012|page=76}}{{sfn|Deakin|1992|page=22}}{{sfn|Booth|2017|page=111}} who had written two treatises on astrolabes: one entitled ''Memoirs on the Little Astrolabe'' and another study on the armillary sphere in Ptolemy's ''Almagest''.{{sfn|Booth|2017|page=111}} Theon's treatise is now lost, but it was well known to the Syrian bishop [[Severus Sebokht]] (575–667), who describes its contents in his own treatise on astrolabes.{{sfn|Booth|2017|page=111}}<ref>{{citation|title=Biographical Encyclopedia of Astronomers|url=https://archive.org/details/biographicalency00hock_878|url-access=limited |editor1=Virginia Trimble |editor2=Thomas R. Williams |editor3=Katherine Bracher |editor4=Richard Jarrell |editor5=Jordan D. Marché |editor6=F. Jamil Ragep|publisher=Springer|year=2007|isbn=978-0387304007|pages=[https://archive.org/details/biographicalency00hock_878/page/n1163 1134]}}</ref> Hypatia and Theon may have also studied Ptolemy's ''Planisphaerium'', which describes the calculations necessary in order to construct an astrolabe.{{sfn|Booth|2017|pages=111–112}} Synesius's wording indicates that Hypatia did not design or construct the astrolabe, but acted as a guide and mentor during the process of constructing it.{{sfn|Booth|2017|page=112}}

In another letter, Synesius requests Hypatia to construct him a "hydroscope", a device now known as a [[hydrometer]], to determine the density or specific gravity of liquids.{{sfn|Deakin|1992|page=22}}{{sfn|Theodore|2016|page=183}}{{sfn|Deakin|2007|pages=104–105}}{{sfn|Booth|2017|pages=113–114}} Based on this request, some writers have proposed that Hypatia invented the hydrometer.{{sfn|Theodore|2016|page=183}}{{sfn|Booth|2017|page=115}} The minute detail in which Synesius describes the instrument, however, indicates that he assumes she has never heard of the device,{{sfn|Deakin|2007|page=105}}{{sfn|Booth|2017|pages=114–115}} but trusts she will be able to replicate it based on a verbal description. Hydrometers were based on [[Archimedes]]' 3rd century BC principles, may have been invented by him, and were being described by the 2nd century AD in a poem by the Roman author Remnius.<ref>{{citation |last=Bensaude-Vincent |first=Bernadette |author-link=Bernadette Bensaude-Vincent |editor1-last=Holmes |editor1-first=Frederic L. |editor2-last=Levere |editor2-first=Trevor H. |date=2002 |title=Instruments and Experimentation in the History of Chemistry |publisher=Massachusetts Institute of Technology Press |page=153}}</ref><ref>Ian Spencer Hornsey, A history of beer and brewing, Royal Society of Chemistry · 2003, page 429</ref><ref>Jeanne Bendick, Archimedes and the Door of Science, Literary Licensing, LLC · 2011, pages 63-64</ref> Although modern authors frequently credit Hypatia with having developed a variety of other inventions, these other attributions may all be discounted as spurious.{{sfn|Deakin|2007|page=105}} Booth concludes, "The modern day reputation held by Hypatia as a philosopher, mathematician, astronomer, and mechanical inventor, is disproportionate to the amount of surviving evidence of her life's work. This reputation is either built on myth or hearsay as opposed to evidence. Either that or we are missing all of the evidence that would support it."{{sfn|Booth|2017|page=115}}