Schema for horizontal dials
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A schema for horizontal dials is a set of instructions used to construct horizontal sundials using compass and straightedge construction techniques, which were widely used in Europe from the late fift
Umayyad Mosque, also known as the Grand Mosque of Damascus
De gnomonum umbrarumque solarium usu
Ibn al-Shatir
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ʿAbu al-Ḥasan Alāʾ al‐Dīn bin Alī bin Ibrāhīm bin Muhammad bin al-Matam al-Ansari, known as Ibn al-Shatir or Ibn ash-Shatir was an Arab astronomer, mathematician and engineer. He worked as muwaqqit in
Schema for horizontal dials
…that a gnomon parallel to the Earth's axis will produce sundials whose hour lines show equal hours or legal hours on any day of the year: the dial of Ibn al-Shatir in the Umayyad Mosque in Damascus is the oldest dial of this type. Dials of this type appeared in Austria and Germany in the 1440s. A dial plate can…
Ibn al-Shatir's model for the appearances of Mercury, showing the multiplication of epicycles in a Ptolemaic enterprise
Gravure originale du compas parfait par Abū Sahl al Qūhī