An Irish Astronomical Tract

An Irish Astronomical Tract, medieval Irish text and manuscript.
Overview.
"An Irish Astronomical Tract" is the title given to a medieval Irish text, created in the first half of the 14th century. It was written in Early Modern Irish, and is based on a Latin translation of an Arabic work "De Scientia Motus Orbis" by Masha'allah ibn Atharī (c.740–815 AD). Of its 40 chapters, 27 correspond to chapters in Masha'allah and the rest to various classical authors.
The name of its scribe and place of composition is unknown, but it is dated by its reference to the use of spectacles.