Editing Gnomon (section)

==Pinhole gnomons==
[[File:Osservazione del solstizio 21.06.12, fi, 20.JPG|thumb|The gnomon projection on the floor of the Santa Maria del Fiore Cathedral during the solstice on 21 June 2012]]
Perforated gnomons projecting a pinhole image of the Sun whose location can be measured to tell the time of day and year were described in the Chinese ''[[Zhoubi Suanjing]]'', possibly dating as early as the early [[Zhou dynasty|Zhou]] (11th century BC) but surviving only in forms dating to the [[Eastern Han dynasty|Eastern Han]] (3rd century).<ref>{{cite book|url=https://books.google.com/books?id=CyssAQAAIAAJ&q=%22pierced+gnomon%22|title=The Asiatic Review|year=1969}}</ref> 

In the Middle East and Europe, it was separately credited to the Egyptian astronomer and mathematician [[Ibn Yunus]] around AD 1000.<ref>{{cite book|url=https://books.google.com/books?id=msaqctAH8OkC&q=perforated&pg=PA6|title=Sundials: History, Theory, and Practice|last=Rohr|first=René R.J.|year=2012|publisher=Courier Corporation |isbn=9780486151700}}</ref> The Italian astronomer, mathematician and cosmographer [[Paolo Toscanelli]] is associated with the 1475 placement of a bronze plate with a round hole in the dome of the Cathedral of Santa Maria del Fiore in Florence to project an image of the Sun on the cathedral's floor. With markings on the floor it tells the exact time of each midday (reportedly to within half a second) as well as the date of the summer solstice. Italian mathematician, engineer, astronomer and geographer [[Leonardo Ximenes]] reconstructed the gnomon according to his new measurements in 1756.<ref>{{cite news|first=Rufus|last=Suter|year=1964|title=Leonardo Ximenes and the Gnomon at the Cathedral of Florence|jstor=227759}}</ref>